# Petzl MYO RXP comes to America



## tnuckels (Jan 14, 2009)

Any one else as interested in the arrival of the Petzl MYO RXP … the 8-140lm (160 boost), programmable, regulated version of the MYO XP?

I have it on good authority that the RXP is crossing the great pond and will arrive on US soil within the week, and be for sale at the $90 mark around the end of the month. A few stateside dealers already show it for sale, although they want ~ $100. Don’t know if they actual have stock.

I’ve enjoyed my Tikka XP for several years now, buying it when they first came out in 2005, then P4 upgrading it in 2007, it’s still my “go to” light, despite owning a new EOS-R. Though my appreciation doesn’t approach the level of fan-boy, I don’t quite understand the certain level of disregard that Petzl seems to enjoy here on CPF. 

Those Froggies are doing a respectable job, so you gotta’ give them their due … vivez et laissez vivez, garçons et filles.


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## Alan B (Jan 14, 2009)

tnuckels said:


> Any one else as interested in the arrival of the Petzl MYO RXP … the 8-140lm (160 boost), programmable, regulated version of the MYO XP?
> 
> I have it on good authority that the RXP is crossing the great pond and will arrive on US soil within the week, and be for sale at the $90 mark around the end of the month. A few stateside dealers already show it for sale, although they want ~ $100. Don’t know if they actual have stock.
> 
> ...



I have had a MYO XP for several years, and it has been a great headlamp. I also did the SSC P4 LED upgrade. How does the new unit differ from the older model (how do the light outputs compare, are there other feature changes, etc).

Thanks, Alan


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## selfbuilt (Jan 14, 2009)

Thanks for the head's up.

FYI, my SSC-modded Petzl Tikka XP is still my go-to light.


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## Vermonter73 (Jan 14, 2009)

Any idea what tint it's going to be? After seeing a Q3 5A I don't see myself getting anything that isn't a good tint ever again.


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## tnuckels (Jan 14, 2009)

Alan B said:


> I have had a MYO XP for several years, and it has been a great headlamp. I also did the SSC P4 LED upgrade. How does the new unit differ from the older model (how do the light outputs compare, are there other feature changes, etc).


Here is a linky to Petzl’s info on the new light: http://en.petzl.com/petzl/LampesProduits?Produit=667, and be sure to check the additional info on the left side of the page, especially the PDF files. Also, one of our foreign correspondents,*Szemhazai, *did a brief review recently here on CPF. 

Basically you can set the levels in the order (low>high, high>low, etc.) and at the level you want (from a predefined table of 10 set levels) for low, medium, and high levels, plus the lower 8 levels are now regulated, plus 3 blinkey modes, plus it’s quite a bit brighter now than the previous model, going from:



Level Lumens
8
13
17
25
34
51
59
71
85
140
Boost 160


I don’t know what kind of performance you are getting with your moded MYO, but I suspect these numbers will be hard to beat.




selfbuilt said:


> FYI, my SSC-modded Petzl Tikka XP is still my go-to light.


I’d say that’s considerable praise, coming from one as versed as *selfbuilt*.




Vermonter73 said:


> Any idea what tint it's going to be? After seeing a Q3 5A I don't see myself getting anything that isn't a good tint ever again.


Sorry, don’t know about the tint, though according to *half-watt*’s sticky at the top of the headlamp forum, Petzl’s using an SSC in their 2008 MYO. Funny how tint, once icing on the cake of a bright light, can become so important once you’ve had a good one.


Here’s to the virtues of patience …


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## jayflash (Jan 14, 2009)

Why bother with an unnoticeable level of boost except to boost sales to the uninitiated? Perhaps a good product featuring a poor gimmick?


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## tnuckels (Jan 15, 2009)

On the Tikka XP, boost is ≈ 43% more light, compared to high, and is a noticeable and appreciated jump. 

I had wondered at the spacing myself, i.e. 9 levels seemingly closely bunched together and then suddenly the big jump to high at 140, with boost only being marginally better than high. Digging a little deeper you get the following increments on the MYO RXP from one level to the next:

8>13 ≈ 63%
13>17 ≈ 31%
17>25 ≈ 47%
25>34 ≈ 36%
34>51 ≈ 50%
51>59 ≈ 16%
59>71 ≈ 20%
71>85 ≈ 20%
85>140 ≈ 65%
140>160 ≈ 14%

My hat is off to anyone who can discern a pattern within these figures. Seems almost random, but perhaps there is an underlying logic or constraint that we are unaware of. Odd as it may be, I don’t know that I’d ascribe Boost’s poor showing to a marketing ploy. It’s almost like they wanted “high” to be large enough to be fairly impressive, ran out of steam when it came time to jump to boost, but left it in there because that’s the way they did it previously.

You are right, of course. At those levels, users will be hard pressed to notice the 20lm jump offered by the boost mode, unless of course, you set high ≤ 85lm. Then boost will seem superb, but I don’t imagine many will set high to less than the maximum and the light even comes with 140lm as one of the default settings.

At least it’s up to the customer, and is a first for the neglected-*******-stepchild headlamp industry to let us make the decision and give us a modern, smart light to play with. However imperfect this first iteration might be I think it is a great leap in the right direction.


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## TGr (Jan 15, 2009)

There is simple logic - dont look this levels as one of ten. One of three. And boost is not tenth - is always quick jump to maximum and after release you are back in current level with no need to cycle thru all levels. Another point - dont look lumens increase, compare regulated time. After level 4 is very simple 1-2-3-4 hours.


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## hopkins (Jan 15, 2009)

Press and simultaneously hold this MYO's two buttons and you'll enter a program mode where each of the lamp's three light settings can be turned up or dimmed down as per the wearer's needs. You balance battery life considerations with brightness output, the dimmest light option misting just a pale eight lumens that's tested to glow for more than three days straight. 

...8 lumens are what I'd use to cook on an extended wilderness hike. And when the uninvited bear shows up I'd blast him with the 160 lumen boost.


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## tnuckels (Jan 15, 2009)

Good points *TGr*. In actual day to day operation Boost is not one of ten but rather as much light as possible, easily accessible from wherever you happen to currently be. *Hopkins*’ example demonstrates this perfectly … working up close at low illumination, but quickly need to extend you vision into the night to check something out.

Also, I was overly focused on lumens part of the table as the sole basis for the spacings, not paying enough attention to the runtime portion. The combination of lumens per runtime seems the more considered approach to evaluating a perspective purchase and is always part of my considerations. Petzl seems to have taken this more serious approach by letting runtime dictate the spacings, leaving the lumens to fall where they may. Fun toy lights can run short, hot and impressively, but as a tool it must do a reasonable job for a known & productive amount of time,


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## hopkins (Jan 15, 2009)

thanks TNuckels. 
As for the lack of respect Petzl gets here in CPF, I've always hoped they
take it as constructive criticism to make their products better, rather than being
discouraged and let other corps take market share.

Their gadgets are already good but the pressure to innovate
is a good thing for everyone. 

And now we have this very nice MYO RXP.


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## uk_caver (Jan 15, 2009)

tnuckels said:


> I had wondered at the spacing myself, i.e. 9 levels seemingly closely bunched together and then suddenly the big jump to high at 140, with boost only being marginally better than high. Digging a little deeper you get the following increments on the MYO RXP from one level to the next:
> 
> 8>13 ≈ 63%
> 13>17 ≈ 31%
> ...


I think I can see a pattern (in the sense of how it's done), if not necessarily any logic as to why.
Leaving aside the top two levels, and looking at the power levels from 8 to 85 lumens, the steps between levels (5,4,8,9,17,8,12,14) seem to be roughly multiples of a unit of 4-and-a-bit lumens, with the multiples being 1,1,2,2,4,2,3,3
If you total up all those multiples of 4-and-a-bit between 8 and 85 lumens, you get 18 units in total, making a unit ~4.277 lumens.

If you use 4.277 lumens as the basic unit, and 1,1,2,2,4,2,3,3 as the number of units per power-level change, you'd get outputs of 
8, 12.3, 16.55, 25.11, 33.66, 50.77, 59.32, 72.16, and 85 lumens, which is pretty close to what is stated.

I'd guess that whatever chip is doing the regulation, it's digitally measuring the current, and the resolution of measurement is ~4.3 lumens, or maybe some power-of-two fraction of 4.3 lumens.

The odd thing is why they didn't arrange the steps as something more logical, like 1,1,1,2,3,3,3,4, which gives reasonably smooth percentage changes (all between 23% and 43%, apart from the initial jump between 8 and 13 lumens)

Having the '...2,4,2,3...' in the sequence does look a bit strange, like for some reason particularly wanted to have a 51 lumen output level rather than a 46.

Though I'm only guessing, one reason why the boost might be so close to the highest normal power level is that Petzl think a few people might want to have the highest power as a normal setting, and they want the boost to still be a _little_ brighter than that, so they can carry on calling it a boost, but they're reckoning on a lot of people setting 85 lumens as their highest power for battery economy reasons, and in that case, the boost really would be a meaningful boost, not just a token.

The 140 lumen high might just be the maximum power they reckon they can run at continuously, or might just have been selected to be a token amount less than the boost level.

Possibly the 85 lumen second-highest setting was chosen for some specific reason, with the 8 lower settings having to fit in below it?
Isn't the unregulated Myo supposed to be about 85 lumens?


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## jzmtl (Jan 15, 2009)

Does it have better heatsinking than myo xp?


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## Phaserburn (Jan 15, 2009)

jzmtl said:


> Does it have better heatsinking than myo xp?


 
That's the big question for me.


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## tnuckels (Jan 15, 2009)

Well, the anal-engineer-type-A side of me says they should subtract the lowest setting from the highest (excluding boost), then divided them equally amongst the positions available. In this case that would be 140 highest – 8 lowest = 132 lumens / 8 positions = 16.5 lumen steps. While this looks neat and tidy on paper, I’ve no idea if reality works like this or if the resulting increments would perform well in practice.

*UKCaver*, you are right about the 2008 MYO XP topping out at 85lm, with a 150lm boost. They would certainly want to position this product in a favorable light, so to speak, compared to the previous one. I don’t know how this compares to older pre-SSC models. Maybe they used a combination of numerology/astrology/psychology/vodoology to derive their numbers.

*Jzmtl*, there are pictures of the insides of the new light in *Szemhazai*’s RXP review post. *Szemhazai* gutted open a 2008 MYO XP for our pleasure as well. It is difficult to tell for sure from these pictures, but the heatsinks don’t appear to be different.

For all I know the older models might have run acceptably at a higher output setting, except for the pesky shut-off circuit. Was there a problem with the MYO XP’s dissipation of heat, other than it being enclosed in a plastic housing?


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## jzmtl (Jan 15, 2009)

Hmm, not sure if I'd trust that heatsinking with 140 lumens. My novatac gets plenty warm on 120, and RXP has no way to vent heat outside from what I can see, it'll step down pretty quickly I bet.


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## likeguymontag (Jan 15, 2009)

tnuckels said:


> Well, the anal-engineer-type-A side of me says they should subtract the lowest setting from the highest (excluding boost), then divided them equally amongst the positions available. In this case that would be 140 highest – 8 lowest = 132 lumens / 8 positions = 16.5 lumen steps. While this looks neat and tidy on paper, I’ve no idea if reality works like this or if the resulting increments would perform well in practice.




The eye responds to increases in light in a nonlinear manner. Still, good idea. Or, they could have programmed it with enough steps to appear infinitely variable.


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## tnuckels (Jan 15, 2009)

That’d be a real pisser if the 140lm level were only good for short periods under normal circumstances, say < 90° outside temp. I can see where you’d want this under “unusual” conditions, but not for it to come into play on a regular basis.


From Petzl’s literature on the MYO RXP:

*Automatic power limitation*
_To avoid overheating the LED, BOOST shuts off after 20 seconds._
_Regardless of lighting level, if the temperature is too high, the light automatically dims toallow the LED to cool (after repeated use of BOOST, for example)._


I guess we’ll just have to get a few and put them through their paces to see what they’re capable of. I’ll probably jump on the early adopter wagon with this one. Hope I don’t regret it.


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## Alan B (Jan 15, 2009)

likeguymontag said:


> The eye responds to increases in light in a nonlinear manner. Still, good idea. Or, they could have programmed it with enough steps to appear infinitely variable.



"Even" appearing steps must be done in "log" or ratio fashion. 160 compared to 140 is an almost imperceptible change. Changes by factors of 1.2 are perceptually very small or invisible. Ratios of 1.4 are modest steps. 

Knowing the runtime is a quite useful with a headlamp. Having settings that are known in run-time is more useful with a headlamp than most flashlights. It is not unusual for a headlamp to be operated for a known period of time, possibly quite lengthy.

I also hope the heatsinking is better than the old model.

-- Alan


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## uk_caver (Jan 16, 2009)

Thinking about it abit more, as well as the 85 lm setting being maybe chosen to be the same as the unregulated Myo XP, I wonder if the 140 lm highest setting was chosen to be just a bit higher than the new 130lm PT Apex?


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## barkingmad (Jan 16, 2009)

Can these be used with rechargeable / lithium primary cells - think I read the previous version had a fault and install of recalling them they just said it should not be used with rechargeable cells?


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## uk_caver (Jan 16, 2009)

It's usable with primary lithium cells and rechargeable NiMH cells.


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## barkingmad (Jan 16, 2009)

So not affected by: http://www.cpsc.gov/cpscpub/prerel/prhtml08/08403.html
*
I have a MYO XP - really they should recall / replace the affected units as I am sure (like me) a lot of people bought them specifically to use with NiMH rechargeables.

It is good to see they have 'fixed' the issue with the latest versions and now can be used with alkaline, lithium primary and NiMH rechargeables!


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## tnuckels (Jan 19, 2009)

A question for those who currently own the MYO XP: Can the battery pack, always shown in the rear opposite the headlight, be easily moved along the band?


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## Ralph_S (Jan 19, 2009)

tnuckels said:


> A question for those who currently own the MYO XP: Can the battery pack, always shown in the rear opposite the headlight, be easily moved along the band?



For practical purposes, the MYO XP battery pack cannot be moved with respect to the headband. However, the headlight slides without difficulty, so the distance between the battery pack and headlight can be adjusted easily. I wear the battery pack somewhat to the right of the center rear, especially when I am wearing the headlamp over a cold-weather hat, because I have a large head.

By the way, the end of the headband can be worked back through the slot more distant from the cable, so the headband only passes through the slot next to the cable. The end of the headband is quite secure in that position, which frees up 3-4 inches of the headband. In that position, the headband no longer covers the flexible battery cover. I have seen no indication that the cover is more likely to come off.


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## tnuckels (Jan 19, 2009)

Thanks *Ralph*. So, with the light and battery pack moved along the headband closer together you could swivel the whole thing to a new position on your head, leaving the light pointing forward, the battery pack off to one side, and a nice flat bit of headband in the back to lie back against? This makes for a much more comfortable configuration for working under the car or reading in a prone position.


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## Ralph_S (Jan 19, 2009)

tnuckels said:


> ... you could swivel the whole thing to a new position on your head, leaving the light pointing forward, the battery pack off to one side, and a nice flat bit of headband in the back to lie back against? ...



To avoid putting a tight bend in the cable, you can use your thumbnail to open the top of the clip that attaches the middle of the cable to the headband, and release the cable. Then you can slide the headlight to the side along the headband. You could just pull the headband through the headlight bracket, but I start by pulling some slack at the middle of the bracket. You then should have a section of headband several inches long, double thickness, upon which to rest the back of your head. If you make the change mentioned earlier, so the end of the headband only passes through one slot, you will have a longer flat section between the headband adjustment slider and the battery pack. 

There is a stop under the headlight to prevent it from aiming straight down, presumably to keep the light out of your eyes and to avoid stress on the cable. If you were to file the stop off, you might be able to aim the light several degrees closer to your chest. 

The light looks uniform. I would want to have the paper turned slightly at an angle, maybe facing slightly downward, to avoid the small amount of glare. 

I haven't tried much reading while lying flat on my back, so I don't know how you would plan to hold a book up for an extended period. If you want to turn your head occasionally, then I think that this setup might require too much repeated adjustment. An alternative might be a Zebralight, which doesn't have a separate cable and battery pack, so probably would allow easier head-turning. On the other hand, flipping the diffuser on the MYO XP takes just a couple of seconds, and a focused beam could be useful if you were to study a distant, greasy part from under a car.


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## tnuckels (Jan 22, 2009)

Thanks again *Ralph* for taking the time to explain what you know about this headlamp.

Guess we’ll soon see what this headlamp can and can’t do, as I just ordered an *RXP* from “*BG*” for the price in my original post. Will post back more info (questions about heat issues, step-down, etc.) after I’ve had a bit of time to monkey around with it. 

Cheers All!


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## tnuckels (Jan 26, 2009)

My Petzl MYO RXP arrived this afternoon. So far I’m quite pleased with it. The programming is very simple, so much so that you won’t need to carry a cheat sheet to remember how to work it, like with some lights. Ah, 1 click = 8lm, 2 click = 51lm, 3 click = 140lm, 4 click = disorienting strobe … just like I always wanted. I can see no difference going from 140lm to boost @ 160lm. Spot beam has a nice hot-spot with “pillowy” edges and good side-spill. Flood is a wash of light. Will try and do beam shots later.

I don’t know about the body of the MYO XP, but the new RXP has what appears to be a vent slot on the bottom of the swiveling head and two more “vent” holes in a depression on the rear of the light’s head. Looking into the bottom “vent” I see bare aluminum, but I am unable to see into the rear vents without disassembly. Not knowing the internals of this light, I can’t say how this may or may not compromise the water resistance of the RXP, and I don’t really feel like finding out just yet. I’ll post more tomorrow.


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## Szemhazai (Jan 27, 2009)

*tnuckels*, there is no difference between XP and RXP heads besides color and driver, they all have small vent on the bottom.

Myo is rated IP54 so it’s only splash proof / dust proof – it’s enough for rain and accidentally drop into the water but it is not waterproof.


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## Outdoors Fanatic (Jan 27, 2009)

I'd buy one if it's truly fully-regulated... I highly doubt it will be, though.


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## Alan B (Jan 27, 2009)

Outdoors Fanatic said:


> I'd buy one if it's truly fully-regulated... I highly doubt it will be, though.



The info on the BG web page indicates that it is regulated at output levels 71 lumens and down. Regulation drops off when the available voltage is too low, and the lamp continues to operate at the available current/output. Using lithium or nickel metal batteries will help regulation significantly. Alkalines just don't have adequate voltage to stay in regulation very long.

I suspect from the quoted characteristics that this is a buck regulator, so it cannot boost the voltage from the sagging alkalines.


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## uk_caver (Jan 27, 2009)

Alan B said:


> I suspect from the quoted characteristics that this is a buck regulator, so it cannot boost the voltage from the sagging alkalines.


Personally, I'd count that as a bonus, if it means the lamp has a long tail rather than a sudden cutoff.


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## Alan B (Jan 27, 2009)

uk_caver said:


> Personally, I'd count that as a bonus, if it means the lamp has a long tail rather than a sudden cutoff.



I agree, especially for a headlamp.


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## tnuckels (Feb 3, 2009)

Man. The minute you set out to do something, life always has a way of getting in the way.

I’ve used the RXP quite a bit since receiving it a few days ago. It’s quite comfortable under normal use and even not so bad to use while lying down with the battery pack as a pillow. I’m still using the alkaline batteries it shipped with. Thus far it has only gotten a tiny bit warm, nothing uncomfortable up between your eyes on your forehead, and I have _not_ noticed any step-down, despite using it on high (140lm) mostly. I’ve ran it on high for about 1 ½ hours outside fixing a burst water line, and then back in the house for another hour or so at medium (51lm). Maybe the cold weather prevented step-down during the extended period at high, as all other times I’ve used it at high power have been for short periods. Only time will tell, but so far, so good.

When I thought about doing beam-shots two problems arose: I have NO white walls in my house, none whatsoever (thanks honey), and I have no common lights to compare with that aren’t themselves modified (thanks to me). Doh!


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## noelex (Feb 3, 2009)

barkingmad said:


> So not affected by: http://www.cpsc.gov/cpscpub/prerel/prhtml08/08403.html
> *
> I have a MYO XP - really they should recall / replace the affected units as I am sure (like me) a lot of people bought them specifically to use with NiMH rechargeables.


Agreed I did :scowl:. Petzl are now moving into more expensive headlights such as the RXP and Ultra. Anyone purchasing one of these premium products should look at the previous quality of "hidden" components, such as wire, and how the company has treated its customers when these components have caused problems.


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## todd92371 (Feb 3, 2009)

I just finished dealing with Petzl customer service this week and they were AWESOME!!!!!!!!!!!!!!!!!!!! Completely helped me and worked with me.No regrets purchasing from them.Top notch. 

Todd


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## noelex (Feb 4, 2009)

todd92371 said:


> I just finished dealing with Petzl customer service this week and they were AWESOME!!!!!!!!!!!!!!!!!!!! Completely helped me and worked with me.No regrets purchasing from them.Top notch.
> 
> Todd


Todd was this in relation to the rechargable battery unsuitability or another problem?


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## hopkins (Feb 4, 2009)

If you refrain from tilting the headlamp up/down unnecessarily like I did,
so the wires are not fatigued and the insulation opens, all Petzl Myo Xp's are safe to use with NimH. At least for many many years. And adding a fuse to the battery
power cable solves all problems. Tilt all you want then.


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## tnuckels (Feb 4, 2009)

I think we are conflating two issues as though they were one in the same: Safety Alerts and Recalls.

These are, perhaps, not technically accurate definitions, but I think we all can see the difference and the merits having of a _Safety Alert_ that is meant as a heads up to the public that a danger exists if you use a product under a set of circumstances, as opposed to a _Recall_ that says a product was manufactured in a defective manner causing it to fail prematurely or pose an undue risk and the manufacturer is now fixing or replacing the product free of charge.

Petzl and the Consumer Product Safety Commission both issued Safety Alerts. You can read Petzl's HERE, and the CPSC's HERE.

As it stands now, much of the MYO line of headlamps is not “compatible” with rechargeable NiMH or LiIon batteries or both, as per Petzl's Battery Compatibility Chart. It’s anyone’s guess if this chart changed substantially after the discovery of the MYO problem, just as it’s hard to know exactly what goes into the decision to approve or decline a type of battery for use with a product.

What they appear to be saying with the Safety Alert is, just to be on the safe side, you shouldn’t use the older products with the two battery types. Better safe than sorry … right? Or at least now you know, because we sent out this foolish little sticker that says so, and now you can make an informed decision.

To suggest that Petzl should recall, fix or replace all of the 322,000 MYO products that it has made and sold over the 5 ½ years prior to discovering and correcting the problem in August of 2008 because 13 of them, or 0.004%, have had a problem is equally imprudent. To further insinuate that the eventual wire failure was a conscious decision on Petzl’s part to save money and that they “hid” the problem under an outer casing is enough to warm the heart of any conspiracy theory junkie. I think the explanation is much simpler. Stuff wears out. Stuff breaks. Stuff doesn’t last forever. Once discovered, they tried harder.

It appears that the MYO products are covered under warrantee for 3 years. If your power wires fray and break under the warrantee period, I imagine Petzl will fix your problem. Until then, do yourself a favor and only use alkaline batteries … unless you don’t mind having an “involuntary makeover” involving the top of your head.

P.S. Still diggin' my new MYO *RXP *.


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## noelex (Feb 4, 2009)

tnuckels said:


> a _Recall_ that says a product was manufactured in a defective manner causing it to fail prematurely or pose an undue risk and the manufacturer is now fixing or replacing the product free of charge.
> As it stands now, much of the MYO line of headlamps is not “compatible” with rechargeable NiMH
> 
> To suggest that Petzl should recall, fix or replace all of the 322,000 MYO products that it has made and sold over the 5 ½ years prior to discovering and correcting the problem in August of 2008 because 13 of them, or 0.004%, have had a problem is equally imprudent. To further insinuate that the eventual wire failure was a conscious decision on Petzl’s part to save money and that they “hid” the problem under an outer casing is enough to warm the heart of any conspiracy theory junkie.
> ...



I think this is a common mistake.The manufacturer claims there has only been "13" instances of the problem. Any search of the internet will discover numerous cases where the wire has sorted out. This is clearly a common manufacturing defect.

"a _Recall_ that says a product was manufactured in a defective manner causing it to fail prematurely or pose an undue risk".
Yes I think this exactly sums the position Petzl is in.

"To further insinuate that the eventual wire failure was a conscious decision on Petzl’s part to save money."
Yes I think they tried to save money.They thought the wire would just be OK. It is not. The wire breaks and shorts out.
Giving consumers a free sticker may reduce there legal obligation, but doesn't solve the problem of substandard materials or design. 

If the wire fails the headtorch stops working irrespective of if the batteries are rechargable or not. Petzl knows there is a problem with the wiring, but has chosen to send a free sticker. Perhaps it should say:

*Petzl wiring may fail at any stage. Don't reley on this heatorch. Please purchase a Petzl RXP, we have fixed the problem, promise*.


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## uk_caver (Feb 4, 2009)

Lamps using the cables in question have been on sale for nearly 6 years. I'm not sure how long I'd expect a manufacturer to guarantee a light for, especially against something which is arguably at least partly a matter of wear and tear.

Insulation not only gets mechanically worn, but it also ages, and at rates varying with conditions of use and storage (sunlight, temperature, etc). It's not always easy to tell exactly how that is going to work out, or what extra trials a cable might face, such as getting yanked when pulling a light out of a packed rucksack.

Even if a manufacturer did some serious testing, how many lights would have to be tested for how long to know *none* would have problems?

If people are doing anything serious, they shouldn't rely on _*any*_ single headtorch.


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## Alan B (Feb 4, 2009)

I thought this thread was about the RXP, not the older units.

Any more reports, comments or experience on the RXP?


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## tnuckels (Feb 5, 2009)

Touché :touche:monsieur *Alan B* … please forgive me for being so easily distracted. Back to the RXP then. 

Even at its lowest setting, which is supposed to be 8lm, the RXP seems quite a bit brighter than my children’s Fenix E01s that are rated at 10lm, but this may be because of Fenix’s wishful ratings or the tint difference between the blueish E01s Nichia GS and the whiter RXPs SSC P4. There are some white cabinets in my garage that I will try and do some beam shots against this evening, time permitting.

I ran the RXP for over hour on the porch today set to high (140lm) in an 80° environment. It is still using the same alkaline batteries that came in it. I set up the light on a table with an old camera light meter in front of it, turned everything on, centered the light meter needle, and waited. At the 1hr 15min I checked the setup. The needle was still centered, meaning it was still putting out the same amount of light, the head of the RXP was just barely warm to the touch, and the battery indicator was still flashing green.

I had originally set the light to 1 click low ~ 8lm, 2 clicks medium ~ 59lm, 3 clicks ~ high 140lm, 4 clicks ~ irritatingly fast strobe, but bumped the medium level down a notch so that when I hit boost ~ 160lm, there is a more discernable jump in the amount of light.

I attached the slim top strap included with the light, mainly so I wouldn’t misplace it, but find that it adds a bit of complexity to sorting everything out before putting the headlamp on and by adding another piece to the puzzle, seems to make it easier to tangle.

If the beamshots against the cabinets comparing the E01 work out, I’ll try and do some showing the different modes (spot and flood) and settings (high to low).

I have looked at some suggestions for taming the light spilled through the diffuser tab, as it is most distracting on my glasses. Additional ideas are welcome.

I’m hoping someone like  *selfbuilt* will do some more formal and stringent testing on this light, but for the time being I am happy to answer any questions to the best of my abilities.


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## Alan B (Feb 5, 2009)

Thanks for the update. Are you planning to do any Eneloop or other NiMH testing? I hate it when alkaline goop leaks all over the inside of a nice light, and the new low self discharge NiMH cells stay ready to go for more than a year, and don't have the leak problem, so I prefer to use them.

I have an old XP and will have to put a 2 amp picofuse into the battery holder so I don't get a free thermal hair restyling.  These small fuses should be easy to deploy in there. Wonder if the new model has one built in.

If you want to spread out the steps evenly, it should be multiplicative, not additive. So the middle step between 8 and 140 is the geometric mean, or square root of (8 times 140) which is 33. Then each step is a factor of four brighter than the other, and the eye will see both steps as similar (unless it is overloaded).

The feature of changing the output steps is really nice. Can the blink step be changed to a fixed step, or changed in intensity or rate?

Is the light from the diffuser tab worse or different from the older model? Perhaps some black sharpie pen ink can be applied at just the right spot.

Thanks,


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## tnuckels (Feb 5, 2009)

I usually run Duracell 2650 mAh rechargeables in my AA lights and Duracell 1000 mAhs in my AAA lights. I haven’t made the jump to the low self-discharge batteries for daily use, though I like them for infrequently used items, as I’m not quite convinced that the loss in runtime (2000mAh vs. 2650mAh) is made up for by the convenience of not having to use them “hot off the charger”. I plan to swap over to rechargeables in the RXP as soon as the alkalines are used up.

A link to this PicoFuse of which you speak, if you’d be so kind? I’ll look see if anything is obvious in the battery holder. That’d be great if the fixed the wire/rechargeable problem with a fuse instead of beefing up the wire or specifying something more flexible. It would certainly be a more universal fix, covering more types of problems on either end of the power line into the foreseeable future. Nah … makes too much sense.

The √ of your eyeball is what now? Dude, what are you, like an ophthalmologist, or something? Yer freekin’ me out here.

The 4th mode, blink, is confined to one of three modes: fast blink, slow blink, and SOS. Beyond those three preset modes there doesn’t appear to be any further customization of blinky mode.

About the diffuser tab: according to Szemhazi, who owns both, there are no outward physical differences between the RPX and the older XP models other than coloring and lettering. A comparison to the pictures of an older blue MYP XP HERE seems to verify that assessment. A sharpie would work for a while, but I’m thinking of a more permanent solution. I have some “liquid electrical tape” that might do the trick, but I’m also looking at the tab and wondering if it’s necessary at all?

I did remember to do the all important “hand :wave: wavey” test to see if, and at how fast, any PWM might be present at the dimmer settings. I retired a new Fenix L0D-CE because I couldn’t stand the slow, jerky PWM it used to achieve its lower settings. I am pleased to report that if PWM is at play, they are running it at a fast enough rate not to be noticeable, irritating, or give one a headache.

Off to the garage for a little late night photo shoot.


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## Alan B (Feb 5, 2009)

*Slightly OT,

Fast blow axial fuse for upgrading old MYO XP's:*

Fuses

The capacity of my high-capacity NiMHs didn't last for very many years, their internal leakage skyrocketed and just about all of them have bit the dust by now. Hopefully the LSD NiMH's will hold up longer. Actually I think they already have for me.

As NiMH's moved to high capacity the internal impedance went up, and the leakage went up. I use them a lot on radios and electronic flashes, and they have not held up well, and were often not ready when needed to be deployed, especially in things like a headlamp or radio that may sit for a few months at times, and then when needed the NiMH cells are dead.

Looking forward to your reports,

Thanks,


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## tnuckels (Feb 5, 2009)

Thanks for the linky *Alan B*. Is this the specific one you were planning to use?

I opened up the battery case, removed the batteries, popped off the plastic covers at either end that hide the battery contacts and what should I see ... a small beige inline “device” about the size of a grain of rice that is part of a red lead wire that goes from the final positive battery connect point, through a trench between the batteries in the sidewall, and then directly into the bundled wire casing, and out the side of the plastic battery housing. 

About 1/3 of it was covered up by shrink tube, but I pulled it back (science marches on) and the markings on one side are CRU2A and on the other side are CO ZAF1. I tried Googling several iterations, but came up empty handed. It’s so small though that a 2 & Z and 0 and O could easily be mistaken. No resistor color code rings, if those things are still in use these days. Could this be your mysterious “Pico Fuse”? 

Does the older battery case have this final positive trace wire, and if so does it have a thing-a-ma-bob in it?

I can hear the bitching now … “Figures they’d put in a nano-couple and cheat us on the bloody wire”.


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## regulator (Feb 5, 2009)

Thanks for the info on the RXP. I'm trying to find someone who carries the light local so that I can look at one. I am really liking this headlamp for my first "higher quality" headlamp. The only other headlamp that I am interested in is the Surefire Saint which is not out yet and a lot more money. I really don't want to spend a lot on a headlamp since I do not use them often. But a good headlamp is a really useful tool.


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## Alan B (Feb 5, 2009)

regulator said:


> Thanks for the info on the RXP. I'm trying to find someone who carries the light local so that I can look at one. I am really liking this headlamp for my first "higher quality" headlamp. The only other headlamp that I am interested in is the Surefire Saint which is not out yet and a lot more money. I really don't want to spend a lot on a headlamp since I do not use them often. But a good headlamp is a really useful tool.



I have a few headlamps but the Myo XP and the Zebralights are the ones I always use.


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## Alan B (Feb 5, 2009)

tnuckels said:


> Thanks for the linky *Alan B*. Is this the specific one you were planning to use?
> 
> I opened up the battery case, removed the batteries, popped off the plastic covers at either end that hide the battery contacts and what should I see ... a small beige inline “device” about the size of a grain of rice that is part of a red lead wire that goes from the final positive battery connect point, through a trench between the batteries in the sidewall, and then directly into the bundled wire casing, and out the side of the plastic battery housing.
> 
> ...



Any 2 amp fuse should do the job here. I'll probably order some next time I'm ordering parts which should be very soon (for the hotwire regulator, but that's OT here).

Pico is just one brand or model designation, the main idea is a physically small device.

I took my XP batteries out and looked. I did not get the battery case ends to pop out, but I pushed them aside slightly and did not see a component, though I did not get enough view to be certain. There is a red wire in a trench across the middle of the bay between cells.

When I get the fuses I'll get more determined to get into the cell terminal area, that is the right place to do the mod.

Thanks for looking in your new RXP cell holder, that is very likely a 2 amp fuse. It is a very inexepensive solution to the problem, and for their legal department would be exactly the kind of fix that would pass muster. No matter the quality of wire it can always fail and this solves it in a fundamental way that any judge or jury would understand.


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## tnuckels (Feb 5, 2009)

regulator said:


> Thanks for the info on the RXP. I'm trying to find someone who carries the light local so that I can look at one. I am really liking this headlamp for my first "higher quality" headlamp. The only other headlamp that I am interested in is the Surefire Saint which is not out yet and a lot more money. I really don't want to spend a lot on a headlamp since I do not use them often. But a good headlamp is a really useful tool.


I got the MYO RXP as a big brother companion to my Tikka XP. More light, longer runtime and a similar feature set were all I was really after and would have probably settled for a standard MYO XP, but after reading about the RXP here on CPF I decided to wait a bit. The regulation is nice, though not a real necessity, and the programmability is fine too as it’s great to set the thing up to closely match my personal preferences, but they’re really just icing on a tasty cake. 

I think Petzl does a decent job building a light worthy of commanding a specific price point, though you pay a small premium commensurate with Petzl’s opinion of themselves. You’re not going to get a Sherman tank for under $100, but it’s no Yugo either. The Saint might save you life, but for the price I’ll follow *UK Caver*’s advice and carry two RXPs.

*Alan B*, do you find the diffused light of the MYO XP comparable to the Zebralights, if a little “lumpier”, and use the Z-lights because they’re light and more comfortable, or are the substantially different enough to warrant a breif explanation of their merits? 

I know its OT, but it’s my thread … sorta’.

Interested in when you finally disassemble you XP battery pack. There, back OT!


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## Alan B (Feb 6, 2009)

I would think comparisons are OT.

I do find the diffused XP to be similar to the Zebralights, though I have not recently put them side by side. I have the AA and 123 cell Zebras. The AA (h50) is not as bright as the XP, the 123 model (h30) is as bright as the modified XP. My attraction to the Zebras is their size and nice flood. I can carry them in a pocket or corner of a case hardly noticing them. The Myo takes a lot more space. If long runtime is needed the Myo has a lot of cells, or if some throw required (like a night hike) the flood/throw mode of the Myo coms in handy. But if there is a short task at close range, or reading in bed/tent, the Zebralight is really excellent. It really depends how far you need to see and for how long. The new Zebralight H60 has more runtime and more light output but it is getting larger and heavier and they have not answered the throw requirement as well as the Myo. The Zebralights are also very waterproof, or appear to be as I have not verified that.

Buy 'em all and then sort them out.

It is not a matter of IF I get an RXP, but WHEN.


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## tnuckels (Feb 6, 2009)

Alan B said:


> I do find the diffused XP to be similar to the Zebralights, though I have not recently put them side by side.


I suspected as much and have held off getting any of the Z-lights, tempted though I was, as this niche is filled adequately by my P4ed Tikka XP. Not quite as small and handy, but I already had it and it fit the bill.




Alan B said:


> Buy 'em all and then sort them out.


Yeah, and let my kids eat 123 batteries during the recession?




Alan B said:


> It is not a matter of IF I get an RXP, but WHEN.


Strong call *Alan B*. I was surprised by the difference in output, as demonstrated by *Szemhazai's* photos, and could see myself justifying such an additional purchase, given the other perks offered by the new version.

I remembered that my EOS-R is still in its original state and would provide a good comparison candidate for the MYO RXP and so I took a bunch of photos in my garage this morning. Unfortunately, until I learn the ins and outs of my new camera, beam-shots that show a meaningful comparison between the two lights, or even different levels of the same light, will have to wait.

Full Auto has made me stupid over the past several years, but at least I got the flash to stay off and the remote to work. I got a book on the camera, I got a weekend free, and I’ll get there, eventually.


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## regulator (Feb 6, 2009)

tnuckels - you are absolutely correct about the price point of the RXP and I think it is priced accordingly. I think the RXP offers a nice balance and you get a very nice headlight for the money. One needs to ask if the same ratio of quality/value is justified in the next level of cost for something like the Surefire. Going from specs alone it looks like the Surefire being aluminum offers some advatages that justifies the additional cost. But depending on how much the light is used is also something that needs to be put into consideration. Two great headlights for sure. Even the RXP would be overkill for what I would mainly use the light for (camping and occasional work). Its this dam flashoholicism that forces someone into buying something overkill!


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## tnuckels (Feb 9, 2009)

regulator said:


> Even the RXP would be overkill for what I would mainly use the light for (camping and occasional work). Its this dam flashoholicism that forces someone into buying something overkill!


There is certainly a point where knowledge of the options offered by the marketplace can grow into an obsession, and new purchases can become more about ticking items off a list, filling a vacant slot on a shelf, or perhaps temporarily quelling some deeper need, than about purchasing a useful tool. I don’t know, it’s certainly a complicated issue if you care to give it much thought … so let’s not.

In the mean time, if you really feel poorly about the extra money spent on the RXP, get yourself a Tikka XP and maybe do a star swap (an easy, feel good mod for sure) if you find the stock XP doesn’t put out enough light. However, buying a notch up-market of your absolute need is a small luxury in the scheme of things, so perhaps give yourself a little gift and go for the RXP, so long as you’ve been good this year.

PS. I’m still working to overcome years of dumbing down by camera’s full auto mode and produce some meaningful beamshots. Even in full Manual there is apparently some contrast, sharpening, and white balance enhancements that you have to dig deep for to turn off, unless you shoot RAW. If it didn’t mean I’d have to get the pics developed and all, it might just be easier to break out the old 1967 Nikon.


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## regulator (Feb 9, 2009)

I am definately leaning towards getting a RXP. It is a nice lamp with a nice quality/feature/cost ratio. I like all the features of this light. It is very versatile and I like the design look of the light as well. Petz did a nice job with the upgrades. Besides the programmability that I think is very useful, I like the fact that it is now regulated.


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## Alan B (Feb 9, 2009)

tnuckels said:


> ...
> PS. I’m still working to overcome years of dumbing down by camera’s full auto mode and produce some meaningful beamshots. Even in full Manual there is apparently some contrast, sharpening, and white balance enhancements that you have to dig deep for to turn off, unless you shoot RAW. If it didn’t mean ....



Easiest way to get around that is to shoot side by side, so whatever the settings are, they are the same for both lights.


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## Szemhazai (Feb 10, 2009)

*Alan B* side by side is good to compare 2 or 3 lights... But what for another 2  You have to master fully manual mode and remember to use always the same settings.


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## Alan B (Feb 10, 2009)

Szemhazai said:


> *Alan B* side by side is good to compare 2 or 3 lights... But what for another 2  You have to master fully manual mode and remember to use always the same settings.



Or just always compare to a common reference light.


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## tnuckels (Feb 10, 2009)

Bit of an update here: I used the RXP again over the weekend to finish up rewiring the heating system for my pump-house. I’ve switched over to NiMH batteries, not because the alkalines were dead, but to have a fresh start point for my vapor-ware beam shots.

I probably ran the light for close to two hours with the diffuser up on high (140lm) this time round. The bottom of the head, back up inside where the LED is tucked, was warm, though nothing anywhere approaching hot or uncomfortable, while the top was as before, just barely noticeably above room temp. I tried to get a digital thermometer, the kind you stick under your tongue, to measure the temp at the two rear vents, but it didn’t register enough to work. 

My forehead was a bit warm, but I was working inside a damp, stagnant 6x6 building. The thought did cross my mind that this extra degree of temperature might not be so pleasant on a warm summer’s night, if I were to need that much light for that long a period of time. It probably wouldn’t be as noticeable if I were outside moving around, and I also wonder if the diffuser doesn’t trap some heat that otherwise would be dissipated through the front lens.


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## Outdoors Fanatic (Feb 11, 2009)

Which stores are selling this light in the U.S?


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## tnuckels (Feb 11, 2009)

I bought mine from BrightGuy.com. Not always the least expensive, but top notch service, information, etc., so worth a bit extra in my book. In this case, at the time I bought, BG was actually around $10 less than others that were listing the light for sale, but by the time you figure shipping, handling, tax, tag, title, it’s anybodies guess who’s really is the absolute cheapest. I’ve seen the MYO RXP as low as $85 and as high as $100+, so BG is in solid at $90 and I can highly recommend them.


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## regulator (Feb 11, 2009)

It is at Brightguy. I am hoping to find it local though.


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## tnuckels (Feb 14, 2009)

Well, here is my attempt at beamshots, for what it’s worth. Shots of the following lights:

*Fenix E01* – Nichia 5mm GS, unmodified
*Princeton** Tec EOS-R* – the new Rebel version with the heavily frosted optic, unmodified
*Petzl Tikka Plus* – modified w/4 Nichia 5mm GS LEDs (*EDIT:* _think these were W rank, b0 tint, so bluer than c0 tint(?) now available_)
*Petzl Tikka XP* – modified w/SSC P4 LED (*EDIT:* _pretty sure it was a pinkish USV0H_)
*Petzl MYO RXP* – programmed to: Click 1 ~ Low = 8lm, Click 2 ~ Med = 51lm, Click 3 ~ High = 140lm, Boost = 160lm, unmodified







*Comparison 1: Left = EOS (low) vs. Middle = RXP (low) vs. Right=E01*







*Comparison 2: Left = EOS (low, med, high) & Reference Shot vs. Right = Tikka Plus (low, med, high)*







*Comparison 3: Left = EOS (low, med, high) & Reference Shot vs. Right = Tikka XP (low, med, high, boost)*







*Comparison 4: Left = EOS (low, med, high) & Reference Shot vs. Right = MYO RXP (low, med, high, boost)*







*Comparison 5: The RXP’s 10 output levels*


Lights were placed 6ft from the target. All images were shot with a Canon EOS 450D (Rebel XSi), ISO=100, 1/25sec, f4.5, in RAW mode. RAW mode was used to keep the camera from enhancing each individual photo’s parameters that occurs when saving to JPEG. All images were then bumped +2 on brightness and set to Neutral picture style before conversion and saving as JPEG in Canon’s Digital Photo Professional program. Images were then scaled, assembled, and cropped with PhotoImpact.

The modifications allowed the shots of low mode beams to show up better, but didn’t wash out the high mode beams. Even with this, the flood beams of the Tikka XP and MYO RXP didn’t show up enough to be worth comparing, though in real life they were quite useable, and the EOS’s mix of spot and flood beam lit more of the surrounding cabinet making it appear brighter as compared to the spot only beams. I guess this is why the experts at beamshots do shots with quicker shutter speeds, to keep spill light from enhancing the photo’s appearance while not adding nearly as much to the lights core beam. That or shoot side by sides

Comments,questions & suggestions for taking better beamshots are welcome.


*EDIT:* _I was surprised that the new EOS looked brighter than the P4ed Tikka XP, at high at least and in the photos, so I did some other comparisons. First was the very scientific “squint” test which confirmed that at arms distance the EOS is a bit brighter at high. Next I got out the old camera light meter, measured both at 6”, and the EOS came out one tick brighter than the Tikka XP on the EV scale (16 vs. 17), whatever that might mean in lumens. Third, despite this surprising conclusion, I recall comparing the two when I first got the EOS, illuminating a distant (*OOPS, TYPO* ≈ *1*00ft) fence at night where the Tikka XP appeared to come out ahead, but I will now have to confirm first impression when it gets dark again._

_I imagine that outdoor beamshots would also be of interest to show color rendition and illumination at greater distances. I know these have been helpful in other’s reviews, but am unsure if I’ll ever get around to them at the rate I seem to be getting things done ‘round here._

*EDIT2: *_In fact the EOS beats out the P4ed Tikka XP in the "fence showdown". I'm recharging all the batteries used in my tests. I'm sure the ones in the RXP and EOS were freshly charged as they were my primary comparison lights, but not so positive about the others as I just threw them in to see how they'd stack up. Must control the number of variables in this if it's to be meaningful and valid. Sorry if I slipped-up._


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## tnuckels (Feb 16, 2009)

Right then. Bit of a rethink on this beamshot thing.

First off, every single battery was hot off the charger that I used in the lights in this go round. They were Duracell AA 2650 mAh & AAA 1000 mAh.

Second, as I become more familiar with my camera, different approaches to the same problem become evident, at least with what I’ve learned to this point in time. This time I shot RAW only captures and had the camera set to Neutral picture mode so there would be less editing later. I also used my brightest light and my dimmest one to try and find a combination of ISO, shutter speed & aperture that would accommodate the entire range of lighting levels without clipping at either end. I came up with ISO 400, 1/15sec, and f4.0. I bumped the RAW captures +1 brightness, converted, saved, scaled, & arranged as before. Camera experts will please chime in here.

The results did vary some from my original attempt, especially on the unregulated lights. I suppose that’s the main benefit of regulation, just so long as it doesn’t leave you suddenly in the dark.

So, let’s begin again:


NOTE: Reference shot has been eliminated as this time around the photos were taken at night in a pitch black setting.

Shots of the following lights:


*Fenix E01* – Nichia 5mm GS, unmodified
*Princeton** Tec EOS-R* – the new Rebel version with the heavily frosted optic, unmodified
*Petzl Tikka Plus* – modified w/4 Nichia 5mm GS LEDs (_think these were W rank, b0 tint, so bluer than c0 tint(?) now available_)
*Petzl Tikka XP* – modified w/SSC P4 LED (_pretty sure it was a pinkish USV0H_)
*Petzl MYO RXP* – programmed to: Click 1 ~ Low = 8lm, Click 2 ~ Med = 51lm, Click 3 ~ High = 140lm, Boost = 160lm, unmodified




*



*
*Comparison 1: Left = EOS (low) vs. Middle = RXP (low) vs. Right=E01*





*



*
*Comparison 2: Left = EOS (low, med, high) vs. Right = Tikka Plus (low, med, high)*





*



*
*Comparison 3: Left = EOS (low, med, high) vs. Right = Tikka XP Spot (low, med, high, boost)*





*



*
*Comparison 4: Left = EOS (low, med, high) vs. Right = Tikka XP Flood (low, med, high, boost)*





*



*
*Comparison 5: Left = EOS (low, med, high) vs. Right = MYO RXP Spot (low, med, high, boost)*





*



*
*Comparison 6: Left = EOS (low, med, high) vs. Right = MYO RXP Flood (low, med, high, boost)*





*



*
*Comparison 7: The RXP’s 10 output levels*



Lights were placed 6ft from the target. All images were shot with a Canon EOS 450D (Rebel XSi), full Manual, RAW capture, Neutral picture style, ISO 400, 1/15sec, and f4.0. 


The EOS still bests the Tikka XP on the light meter test by about ½ tick and is still brighter against the fence, but just by a little. The EOS is definitely the best bang for the buck in this class light, yet despite this I still find myself reaching for the Tikka XP more often than not for its small size and beam that I can control to suite the situation at hand

Comments, questions & suggestions for taking better beamshots are welcome.


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## Phaserburn (Feb 17, 2009)

Very nice. I've been on the fence about both the new RXP and EOS for several weeks. I have the older versions of both.

At what range were the shots taken at?


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## tnuckels (Feb 17, 2009)

Hi *PB* … nice to know the slithering things that live on your property haven’t managed to drag you off to their layers yet.

Both the light and camera were ≈ 6ft from the white cabinets, camera mounted on a tripod, with the light positioned above the camera about where the external flash would be. 

I realize that having a bigger surface to show the side spill better would help the shots, as well as moving the lights closer to the target than the camera, but this did a pretty good job for a quick and dirty production. Even at this, it’s surprising how much work goes into something as simple as my effort, and really makes you appreciate the other CPFers that do such a thorough and consistently great job reviewing lights for us.

Unfortunately, this set of cabinets in my garage is the only large white surface that I have available. I did clean the upper units up a bit so that dirt wouldn’t appear as artifacts. I also considered shooting with the light centered where the four corners come together, but thought that so many lines and the cabinet handles would be distracting.

Moving the lights closer to the target is an option so that the side spill is contained within the frame of the photo, but will require some additional setup to get them all positioned consistently at the same place and targeting the same given point, in my case a golf tee stuck between the cabinet doors.

I got the RXP because I am starting to do some caving. While I wouldn’t call the caving we do very serious, it’s still nice to be able to light up a big room or see the top/bottom of a shaft, plus not have to worry as much about your battery status, which were tasks that neither the EOS or Tikka XP were quite up to.


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## Phaserburn (Feb 17, 2009)

tnuckels said:


> Hi *PB* … nice to know the slithering things that live on your property haven’t managed to drag you off to their layers yet.


 
Ha, yes, not yet, anyway. I suppose it's getting to be that time again, to head off and see what else can be seen; been awhile now. But that's a story for a different, um, thread.
:candle:

So, how much brighter, totally subjectively, would you say the RXP is compared to the new EOS? I hear you about the batt meter and diffuser. Hmm, any idea of current draw on high for both? That would be pretty telling too as they both use 3 cells, albeit AAA vs AA.


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## tnuckels (Feb 17, 2009)

I’d say the EOS at high is equivalent to the RXP at Medium, which I have set to 51lm. This makes sense as the EOS is rated at 50lm and I think is born out in the photos, despite the EOS looking as though it is perhaps doing more because its hotspot is blended with its spill and its spill is more centralized. However, jumping to High, which I have set to 140lm, or Boost at 160lm, only appears to be about double the EOS at 50lm, when the numbers say it should be triple. 

I’m guessing that at short distances the extra output is wasted but that it might be more evident when lighting up a larger and/or more distant target. Though I’ve no real knowledge on the subject, I’d think that your eyes would work a lot like a camera on auto by trying harder to see the dimmer light source and filtering out the more powerful ones in order to protect themselves and thereby tending to push both toward a more central averaged appearance. I’ll also have to re-read the explanation on the ceiling bounce test as many seem to use it as a relatively more accurate measure of a subjective test.

I’ve seen current draw figures for both lights around here somewhere, but I’ll break out the Ohm meter later this evening and see what I come up with. For now though, I’ve gotta’ run.


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## likeguymontag (Feb 17, 2009)

tnuckels said:


> [...] Boost at 160lm, only appears to be about double the EOS at 50lm, when the numbers say it should be triple. [...] Though I’ve no real knowledge on the subject, I’d think that your eyes would work a lot like a camera on auto by trying harder to see the dimmer light source and filtering out the more powerful ones in order to protect themselves and thereby tending to push both toward a more central averaged appearance.



Bingo. Our eyes are definitely nonlinear. We perceive linear increases in light intensity to be logarithmic.


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## tnuckels (Feb 18, 2009)

Hey *PB*. 

While I was at it I did all the lights. Hope I got it right, as I don’t test current very often. I pulled one battery, ran a wire from the battery + terminal to the + connection on the light, ran one end of the Ohm meter to the battery’s – terminal and the other end of the Ohm meter to the – connection on the light, and cycled through the output levels while recording the results. 

Just don’t shoot the messenger … he’s doing the best he knows how.

EOS-R ≈ 25mA Low 
98mA Med
126mA High

MYO RXP ≈ 63mA Low 
128mA Med
148mA High

Tikka XP ≈ 25 mA Low 
57mA Med
84mA High

Tikka + ≈ 18mA Low 
42mA Med
90mA High

Hope this helps some.


*EDIT: *Hmmm, seems that my figures don’t match *Szemhazai's* for the RXP on high. Guess it’s time to bust out the old Ohm meter manual. After years of providing others with support, I know when it’s time to RYFM.

*EDIT2:* Well, as far as I can tell I've got it right. EE's might want to chime in here and confirm this approach or set me straight.


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## PETZLvsPRETZEL (Feb 27, 2009)

Automatic Power Limitation
To avoid overheating the LED, BOOST shuts off after 20 seconds..

I've just tried it on mine and it doesn't work..Anyone could explain me?


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## tnuckels (Feb 28, 2009)

Interesting, held mine on for 2min and no shutoff, even though the literature does state that Boost should cut out after 20 seconds, or if the LED is in danger of overheating. Either someone forgot to edit the manual for the RXP or perhaps this is not implemented properly in the firmware in the light, or maybe its just not getting hot enough. Still …

Can anyone else confirm this behavior on their RXP or on their older MYO XP?

One other thing I’ve noticed about the button sequencing on the RXP vs. the Tikka XP: on the Tikka if you have the light on anywhere in the 4mode sequence (high, med, low, blink) and press Boost, it overrides the timed lock-in that would cause the next click of the main button to shut the light off. Example, normally if I was at say Medium level long enough, then pressed the main button again the light would turn off, but if I press Boost first, then the next press of the main button takes me to Low, then Blink, etc. I sort of like this feature/flaw of breaking the default sequencing by pressing Boost.

The RXP does not work like this. Get to a level and stay there long enough for it the be “set” and the next time you press the main button, no matter if you’ve gone to Boost, the light will go directly to Off. No biggie, just different.


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## tnuckels (Mar 1, 2009)

I eamiled Petzl the following:

_I recently purchased a MYO RXP, and have a question about Boost mode. Your literature says that Boost will shut off after 20 seconds operation, but mine does not. I have held the button down for several minutes without the light shutting down. Is this an error in your literature or some problem with the light. I know of at least one other RXP that exhibits the same behavior._

_Thank you for your time and attention,_

Will post back  when/if they respond.


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## Szemhazai (Mar 1, 2009)

What are you expecting ? The power consumption of the boost and high (10 level) is almost the same - so it is impossible for the boost mode to be turned off after 20 seconds from overheating because the 10 mode will do the same.

Simple mishap in the manual... 


```
V-in   I-In     P-In   V-led  I-led    P-led
high    3,65   0,8215   3,00   3,28   0,8458   2,77
boost   3,63   0,8522   3,09   3,29   0,8608   2,83
```


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## Alan B (Mar 1, 2009)

Szemhazai said:


> What are you expecting ? The power consumption of the boost and high (10 level) is almost the same - so it is impossible for the boost mode to be turned off after 20 seconds from overheating because the 10 mode will do the same.
> 
> ...



Excellent point. Probably leftover marketing hype from the earlier model.


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## tnuckels (Mar 1, 2009)

Szemhazai said:


> What are you expecting ? The power consumption of the boost and high (10 level) is almost the same - so it is impossible for the boost mode to be turned off after 20 seconds from overheating because the 10 mode will do the same.


That was essentially my point in a question that I asked some time back in another thread: were there any “real” heat issues in the older models at High and/or Boost, and perhaps the light could run OK at Boost for much longer periods. I never got an answer or even a ventured guess …

Yes, I would assume that the draw and heat produced were quite similar on High vs. Boost. But because High doesn’t run through the cut-off-circuit it continues to work for long periods of time. Although, if the manual is to be believed, then the IC may be receiving some feedback about temperature conditions from the Boost circuit that it uses to determine if the light needs to step down or be shut off during normal operation.

I always thought that Boost, which is routed around the backside and feeling the warmth given off from the LED to the heat-sink via the thermal grease, was shutting down via a simple electrical heat activated breaker, like they use in a lot of electric motors. However, with the addition of a smart IC it could now be a timed cut-off, if such logic is available in the chip they’re using.




Szemhazai said:


> Simple mishap in the manual...


Yep, with the advent of cut-&-paste I think the instances of errors like this have gone up exponentially.

PS. *Szemhazi*, &/OR *Alan B*, as you booth are much more versed in EE issues, would you verify my method of measuring current draw a few posts back? Thanks!


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## Alan B (Mar 2, 2009)

tnuckels said:


> That was essentially my point in a question that I asked some time back in another thread: were there any “real” heat issues in the older models at High and/or Boost, and perhaps the light could run OK at Boost for much longer periods. I never got an answer or even a ventured guess …
> 
> Yes, I would assume that the draw and heat produced were quite similar on High vs. Boost. But because High doesn’t run through the cut-off-circuit it continues to work for long periods of time. Although, if the manual is to be believed, then the IC may be receiving some feedback about temperature conditions from the Boost circuit that it uses to determine if the light needs to step down or be shut off during normal operation.
> 
> ...



Your meter hookup is correct, current is measured in series. Take care to avoid measuring voltage when the meter is configured for current as it is a short circuit and this can damage the meter, blow the fuse, and/or damage the circuit under test. Meters used for measuring current are generally referred to as amp meters or ammeters rather than ohm meters. DMM covers it all..

When I modded my XP there was a diode in thermal contact with the heatsink. This leads one to the conclusion that it is being used as a temperature sensor (which is common). There could be a timer function in the IC as well, or it could just be the 20 seconds is a typical value to the temperature cutoff. I've never had the patience to test it for that long, it isn't particularly useful or easy to use the burst mode. If it were a 20 second burst that toggled on and timed off I would be more interested. If it is temperature it would be dependent on many things from the environmental temperature and wind velocity to the LED efficiency bin and battery voltage.

Judging from the size and mass of the heatsink I suspect there is a real issue, as the heatsink is small, thin and not well cooled due to the enlosing plastic.


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## uk_caver (Mar 2, 2009)

Current measurement *can* be tricky, especially for unregulated lights, since the meter will add resistance to the circuit, and that can affect readings, especially at higher currents, and low-current ranges on a meter.

However, I'd guess that for the readings made above, the inaccuracies introduced by having the meter in the circuit probably wouldn't be great.


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## tnuckels (Mar 3, 2009)

I sent my request for info about the MYO RXP’s Boost mode / 20 second timeout on Saturday and received an email with contact names and phone numbers Monday morning. I spoke with a Petzl representative Tuesday morning who researched the question and called me back Tuesday afternoon. His initial answer was that the 20 second cut-off should work, but after speaking further with him, he is going to research further up the chain for additional verification. 

I’ll post back when I receive his reply.

I have some scraps of additional information about the 2009 lineup, but I’ll post them over en the appropriate thread.




Alan B said:


> Your meter hookup is correct, current is measured in series.


Thanks for the feedback *Alan B* on my DMM setup. Yes, I did re-configure the test leads on my DMM, leaving the black lead in COMmon and moving the red lead from the VΩ connection over to the µAmA connection. It’s not a fancy meter, a BK Precision 2470A, but all I wanted was one that was small, fairly rugged, would measure current, and didn’t cost an arm and a leg.





Alan B said:


> Judging from the size and mass of the heatsink I suspect there is a real issue, as the heatsink is small, thin and not well cooled due to the enclosing plastic.


SSC specs a maximum temperature for their product, which has some margin of “comfort” built into it. Unless someone has one of those IR heat measuring devices, like I’ve seen Peter (ARC) and Don (McGizmo) use to test their designs, then I suppose we’ll never know for sure if Petzl’s heatsink and 3 vent design is working to keep the LED within spec. At least it’s not completely entombed in plastic, and I suspect it was a conscious decision to give up waterproof claims for the sake of cooling ability. Still, I’m sure we all would rather see an aluminum housing or external heatsink as we know these designs are apt to work better


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## PETZLvsPRETZEL (Mar 3, 2009)

Just did the same friday night, well nobody from PETZL emailed me back at the moment..Hope you will post back when you'll have an answer Tnuckels! 

P.S. If other members got MYO RXP with "Automatic Power Limitation" working/or not, just let us know!


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## tnuckels (Mar 6, 2009)

Spoke again with Petzl support about the 20 second Boost time-out and this is my understanding of his explanation:

On the Tikka XP, MYO XP and MYO RXP you can jump to Boost mode from anywhere (off, low, med, high, strobe) but once you exceed Boost’s time-out you then drop to the next highest level available. For the Tikka that’s going from 50lm down to 35lm (IIRC the original LED’s figures); for the MYO XP that’s going from 150lm down to 85lm; but for the MYO RXP that’s only going from 160lm down to 140lm. Releasing Boost then drops you back to the mode that you started in.

So, from Boost to High is a noticeable drop on the previous lights, but not so easy to discern on the new MYO RXP.

Literature is correct, light is correct, everybody is happy …


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## Szemhazai (Mar 7, 2009)

Hehe, what a nice explanation... :naughty:

So there should be 20 lumens difference between boost and 10 level. 

On batteries : 

```
V-in   I-In     P-In   V-led  I-led    P-led
high    3,65   0,8215   3,00   3,28   0,8458   2,77
boost   3,63   0,8522   3,09   3,29   0,8608   2,83
```

*15mA difference*

On NIMH's :

```
V-in   I-In     P-In   V-led  I-led    P-led
high    3,50   0,7431   2,60   3,25   0,7183   2,33
boost   3,45   0,7562   2,61   3,26   0,7483   2,44
```

*20mA difference*

Lets do some math... At 800mA P4 gives 180 lumens, so linear aproximation -> 1mA = 0,225 lumen 
15 * 0,225 lumen = 3,375 lumen
20 * 0,225 lumen = 4,500 lumen

So 5 lumen difference ok, 20 never... :nana:


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## North61 (Mar 7, 2009)

I broke down and bought one of these RXP lights. It looks great. I plan to program it down in power as 140 Unregulated Lumens at level 10 would seldom be needed and the 20 minutes or so powerful shine time doesn't seem particularly useful.

Programmed down to Level 1/3/7 should give a combination of useful light and burn time with the boost used for the occasional route finding gander. I like having a low, low for in the tent use. Programed like this the boost again makes sense.

This ought to be the ultimate X-Country Ski-Camping light.

My wife can inherit my EOS.


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## tnuckels (Mar 8, 2009)

I don’t pretend to know if any of the figures for each lighting level stated in the literature translates well into reality. Given your results, *Szemhazai*, I would say not necessarily.

However, my understanding is that each electronics package built will produce slightly different output levels. Likewise, each manufacturer only claims that their LED falls within a given range of tint and flux that they deem allowable. So, combining the two variables will produce an even wider range of results. Each light’s manufacturer then must determine an acceptable range for product quality control, hopefully rejecting those that fall beneath a certain level.

Let’s face it, only small manufacturers of high end lights can take the time to tightly specify bins, and then further narrow their variables by hand selecting LEDs, and then calibrate each output level based on the unique combination of equipment. Of course you’re required to pay more for this level of attention to detail, and you are either willing to swallow those costs or pass up the purchase. In addition, each round of production may also bring a new asking price.

On the other end, mass manufacturers look at product placement within certain price points as their goal, positioning each to compete against other manufacturers products and trying not to have a lot of overlap within their own lineup. They then see what can be built within those constraints. The costs of the components + manufacturing + marketing + profit margin + S&H + warrantee work + dealer margins, etc., are all parts of a long equation that goes into delivering a $100 headlamp to the public. And it’s a public, I might add, that has a high expectation that each new batch of product will come at same price as the last batch.

And so, it’s not always deliberate shortchanging or corporate greed or shoddy workmanship that cause us to be disappointed with some aspect of a product, but simply the constraints of what can be built for a given price. If you want something better the simple solution is to belly up to the bar and lay your money down.

ANYWAY, sorry for the tangent. We now return you to our originally scheduled topic.

The more I use the RXP, the more I like it, but mostly _plan_ to use it for more "serious” activities, like caving, or when I don’t want to worry so much about runtime or need the extra light. And, I’ll probably still turn to my smaller, lighter AAAx3 headlights, like the EOS or moded Tikka XP, for more frequent, everyday jobs.

Outdoor beamshots are still on my to-do list whenever time permits.




North61 said:


> My wife can inherit my EOS.


Ah, the satisfying *C*over*Y*our*A*nus logic of trickle down. "Yo baby, look what I got you for your birthday!" It gets even more exciting with children as you can then add more layers of upgrades to the scheme.


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## North61 (Mar 8, 2009)

tnuckels said:


> Ah, the satisfying *C*over*Y*our*A*nus logic of trickle down. "Yo baby, look what I got you for your birthday!" It gets even more exciting with children as you can then add more layers of upgrades to the scheme.



Exactly!!!!!

I have two kids but they are young enough that the Black Diamond Ion still suffices. They get older every year thugh!

Also...I'll find myself saying...Honey can I borrow "your" EOS.


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## tnuckels (Mar 13, 2009)

When I spoke to Petzl with questions about the RXP the topic of the older XP safety notice came up. I will try and relay my understanding of the problem, as well as the fix. Others more versed in electronics are invited to chime in, in case I go astray. As well, there is some amount of, not necessarily conjecture on my part, so much as trying to connect the dots from various sources, but nevertheless it is prone to some degree of error.

As has been mentioned by others, members that I feel are far more qualified to discuss serious headlamp use as well as electronics and manufacture of lights, any light that uses external wiring is susceptible to additional wear & tear. In the case of a swiveling headlamp, other than one off incidents, much of the day in, day out stress is focused at the point where the wires enter the moving head of the light. This fatigue can lead to breaks in the copper wire, openings in the insulation, or both, which then allows for shorts to occur.

In the case of alkaline batteries, they can not supply enough sustained current to endanger the headlamp user, just damage the light. NiMH rechargeables can deliver sufficient current to melt components, possibly worse. For this reason, Petzl issued a Product Safety Alert, warning users to refrain from their use. It is not clear why LiIon batteries are still “incompatible” with the older MYO XP and MYO XP Belt, according to Petzl’s Battery Compatibility Chart, and yet are OK on the MYO RXP. Maybe some change in the circuitry to allow for their initial over voltage?

Knowing that they could not reasonably engineer wire thick or strong enough overcome the laws of material deterioration, Petzl opted instead to put in a safety valve that would disconnect the entire system from its power source in case of a problem. This solution actually works more universally as it addresses not only the wire issue, but also works to alleviate unforeseen future problems at the battery pack or lamp ends of the equation.

The fix was to install an inline micro-fuse at some point during the manufacture of the 2008 MYO XP (gray) model. All subsequent MYO XP and RXP lamps have the fix in place. The terminal covers at both ends of the battery pack say “Rechargeable battery compatible” to indicate a fixed unit.

I do not know if this fix acts like a fuse that once blown has to be replaced, or more like a breaker that once tripped can be reset or resets itself.

Here is the Pico-Fuse that Alan B is planning to use to enhance the safety of his older MYO XP headlamp. To judge from a brief perusal of his Hotwire Regulator project, I’d say his expertise on this is quite sound, but everyone should make their own decision. 

Below is a picture of how this fix is implemented on my MYO RXP. 








This should, for the most part, alleviate concerns about the wiring on current RXP model, as well as serve as a guide for those who wish to add this to their older model headlamps. I convey all this in an attempt to simply be helpful. I don’t have any stake in Petzl. If they willfully screw us, I’ll be the first to jump in with both feet. In addition, I am sure initially that I would have also been chapped if I owned an older, though lightly used, model, heard about a “recall” and then was told I would be receiving a sticker to “fix” my $75 headlamp. However, my sympathies simply can not be extend to those who refuse to do the follow-up work required to gain a better understanding of the problem, the fix, and simply sit by and maintain that they are entitled to a new headlamp, all the while contributing nothing of use for the rest of us.


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## Szemhazai (Mar 13, 2009)

tnuckels said:


> Here is the Pico-Fusethat Alan B is planning to use to enhance the safety of his older MYO XP headlamp.



And it was the first thing that I have to remove after I get it in my hand’s  - when I was taking measures I must have short circuit the board and then spent almost an hour looking WTF has happened... :tinfoil:


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## tnuckels (Mar 13, 2009)

Like I said, “prevents unforeseen future problems at the battery pack or lamp ends of the equation” (read: like *Szemhazai* poking around where he shouldn’t be). :whoopin:

Dude, your Mama needs to call Petzl right now and thank them for saving your scrawny butt. Without that fuse in place, you’d have been turned into a French Fry! Or even worse, some sort of freakish dancing banana creature! 

Seriously though, once tripped does this device reset, or does it need to be thrown out and replaced with a new one?


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## Szemhazai (Mar 13, 2009)

I like simple solutions... :huh:

Replace original wire with the HQ wire :twothumbs


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## uk_caver (Mar 13, 2009)

tnuckels said:


> Seriously though, once tripped does this device reset, or does it need to be thrown out and replaced with a new one?


At least at my electronics supplier, Picofuses are just small fuses, so they're single-use only.


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## kwieto (Mar 13, 2009)

tnuckels said:


> Seriously though, once tripped does this device reset, or does it need to be thrown out and replaced with a new one?



And does anybody know what is the "technical" name and parameters of that fuse?
I think I'll install it "for sure" - the wire from battery copartment to the lamp is the first thing which is breaking during the longer usage - i had similar problems with old zooms - both I own had problems with wires.

EDIT: OK, I found the names and prices (c.a. 1 USD), but what should be amperage of that thing? I can chooose from 0,5A up to 7A


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## cave dave (Mar 13, 2009)

You wouldn't want the fuse to reset, because it isn't like an internally frayed wire is going to fix itself.


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## kwieto (Mar 13, 2009)

cave dave said:


> You wouldn't want the fuse to reset, because it isn't like an internally frayed wire is going to fix itself.



But there are automatic fuses, which can be reset after the problem is fixed (or even are resetting automaticaly).
But I can't find that kind of fuses in the micro/pico size.

Back to the question - what Amperage should have that thing? Myo shouldn't get more than 0.7A so 1A will be enough? 
Or should I place something stronger? What do you think will be correct - not too strong, not too weak?


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## Szemhazai (Mar 13, 2009)

*kwieto*, 1,5A should be OK.


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## kwieto (Mar 13, 2009)

Dzięki :")


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## tnuckels (Mar 14, 2009)

Szemhazai said:


> Replace original wire with the HQ wire


Hmm, I’m sure you picked something suitable, but it looks like lamp wiring in the picture. Bigger seems like an obvious answer, but is not always the best solution. At least now you’ll be able to see when your wires are going out on you.




kwieto said:


> And does anybody know what is the "technical" name and parameters of that fuse?


The link, originally provided by *Alan B*, back in post# 88 points to a 2A fuse.




cave dave said:


> You wouldn't want the fuse to reset, because it isn't like an internally frayed wire is going to fix itself.


Yes, I had thought about that. The first device like this that I encountered was used in HVAC motors and was tripped by excessive heat. In that case you do want it to reset once the motor has cooled down, and once you’ve fixed the problem.




uk_caver said:


> At least at my electronics supplier, Picofuses are just small fuses, so they're single-use only.


So, if they do blow for some reason Petzl’s going to get a call. A $100 headlamp, shot down by a 50¢ fuse that’s soldered in place. I guess they’re counting on it never blowing.

Seems a better solution might have been to use something like the connectors in a punch down block, which are basically metal tabs with a narrow V notch in them. In the case of the headlamp, one tab is connected to + power, the other tab is connected to your wires leading to the light, and spanning the gap between the two tabs is your, now user serviceable, pico-fuse. You press the fuse leads firmly down into the narrowing sides of the V which “bite” through the insulation and into the wire a bit and holds them securely in place.

And they call themselves engineers. Bah, engineering something for the repairs department to do …


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## kwieto (Mar 14, 2009)

tnuckels said:


> Seems a better solution might have been to use something like the connectors in a punch down block, which are basically metal tabs with a narrow V notch in them.



In fact that is how the wire is connected to the "+" joint in the Myo battery copartment. 
There is "V" shaped contact to which the cable is attached and then soldered (you can see that contact on the pictures in post #88)
It seems that it can be used as a fuse connector. The only thing is to get similar, enough small connect for the other side of the fuse, and voila! fuse should become serviceable.

But from the other hand, according to the concept, this fuse should work only when you will broke the wire enough to make a short circuit.
That will be hard to repair in the field. 
If you have tools to repair it, you also shouldn't have any problem to replace soldered fuse with the same tools. And if you don't have that kind of tools and you won't repair the cable, replacing only the fuse is useless, because it will immediately break again.

So I am not sure if there is any sense to make it "field serviceable"?
EDIT:
You can choose also the "indirect solution": solder the fuse to the wire and use existing V-shaped connector on the other side of it.
In "emergency situation" the part attached to the wire should be easy replaceable by cutting out the broken fuse and attaching the new one only with your hands and piece of thermo-shrinking isolation (all to do with a knife, hands and the lighter/matches).
The other side of the fuse you easily put into the V-shaped connector in the Myo's battery copartment and it should work until you can make the real service to the wires and fuse.
The bonus is that if you don't have any fuse you can (on your own risk) attach the wire directly, as it was originally.

BTW, forgive me a question (I am not really familiar with electronics) - is there any sense to install the same kind of fuse on the "-" cable?


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## noelex (Mar 14, 2009)

kwieto said:


> is there any sense to install the same kind of fuse on the "-" cable?


No need for a second fuse on the - cable. A short circuit can only occur when the + and - are connected, so a fuse on one conductor is all that is needed.
The problem with a fuse is that it decrease the reliability, particularly when combined with poor wiring. Reliability is high on my list of requirements for a headtorch.
I would not buy an RXP for this reason, even if it was not a Petzl product.


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## kwieto (Mar 14, 2009)

Heh, I've bought Mammut X-zoom recently (according to shops info it supports alkalines, NiMH and Lithiums as well) so I think it will become my favorite, most reliable light.
Then I can play with Myo without risk - it will stay only as a backup or "car emergency" light.
I plan to install that fuse (I mainly use rechargeables and in fact I have nice 3xNiMH set dedicated for Myo) and then I'll replace LED to the SSC P4.

As a final I should get a nice blue coloured "Myo XP 2008" :")

But you are right, that kind of stuff which is a headlamp should be "100% sure". Petzl had problems with the cables before (the Zoom model, which I mentioned before, in my case was replaced several times due to the cable problems) and they didn't learn from the past cases... The wires in Myo are pretty thin, regardless that the outer isolation is thick (and too stiff in my opinion).

I hope that the Mammut lamp will behave better.


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## uk_caver (Mar 14, 2009)

What's the point making the fuse easily user replaceable?

Assuming the headset electronics don't fail and draw a large current, (which would likely mean the end of the lamp anyway), as cave dave points out, the likeliest reason for the fuse blowing is the cable wearing through, and in that case, replacing the cable is likely to be more of a pain than replacing the fuse.

The only other obvious cause of the fuse blowing would be someone poking around inside the headset while the battery pack is full, and someone doing that should be capable of changing the fuse if they cause it to blow.

If/when I'm concerned about the ultimate reliability of a headlamp, I keep an eye on the state of the cabling, the same way I keep an eye on the cabling of domestic appliances that get frequently moved around.


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## noelex (Mar 14, 2009)

uk_caver said:


> What's the point making the fuse easily user replaceable?
> 
> 
> If/when I'm concerned about the ultimate reliability of a headlamp, I keep an eye on the state of the cabling



I agree about the fuse there is no point making it user replaceable. Petzl need to specify higher quality wiring and/or strain relief for the wire.
I believe the internal fracturing of the wire can occur without any external signs, so keeping an eye on the state of the cabling wont necessarily show a problem.


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## uk_caver (Mar 14, 2009)

That's the thing that doesn't yet seem to be clear - what *has* actually happened when the wire has failed?
Is it a case of general wear-through, or of the outer sheath being too stiff/durable compared to the cores, or the sheath stretching and leaving cores under tension, or something else?


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## Szemhazai (Mar 14, 2009)

uk_caver said:


> That's the thing that doesn't yet seem to be clear - what *has* actually happened when the wire has failed?
> Is it a case of general wear-through, or of the outer sheath being too stiff/durable compared to the cores, or the sheath stretching and leaving cores under tension, or something else?









As you can see there are 2 possibilities : 
most common : the core isolation is to stiff and after some time it starts cracking, in the same places the core wire will crack and the headlamp stops working. 
rare, but more problematic : in the places that core isolation cracked, + and - will connect and depending on power source we will have hot-wire or fire-wire


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## noelex (Mar 14, 2009)

Petzl is still apparently using this same wire on the RXP. They really should spent an extra 50 cents and use some wire with a more flexible and durable core


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## tnuckels (Mar 14, 2009)

kwieto said:


> In fact that is how the wire is connected to the "+" joint in the Myo battery compartment.


But because it is soldered “permanently” in place it requires many times the effort required to replace it.




kwieto said:


> _{SNIP}_ replacing only the fuse is useless, because it will immediately break again. So I am not sure if there is any sense to make it "field serviceable"?


A frayed wire that is shorting out is only one of many scenarios that might cause a failure. There are all sorts of transient or one time conditions that might cause a fuse to blow, a breaker to trip, or a bulb to burn out. Having the failed component “user serviceable” just removes some of the necessity of involving the manufacturer in the fix and some of the hassle for the user involved in getting the device back up and running. Here are a few instances where you wouldn’t want to be stuck with a hard soldered item, which everyday users can commonly fix on their own, and for which the cause of the original failure might never be known or encountered again:

Bulb in an incandescent light 

Fuse in many small electronics & appliances 

Reset button on your power strip




kwieto said:


> Petzl had problems with the cables before (the Zoom model, which I mentioned before, in my case was replaced several times due to the cable problems) and they didn't learn from the past cases... The wires in Myo are pretty thin, regardless that the outer isolation is thick (and too stiff in my opinion).


None of us really know what efforts Petzl has likely gone through over the years in search of an indestructible cable, just as none of us know exactly what differences there might be between the cabling used in successive generations of the MYO. Looks the same and is the same are two different things. Likewise, none of us really knows the age or condition of the units that failed that caused them to rethink this. Maybe it was equipment used hard for 5 years, or maybe it was “only used on Sundays by a little old lady in her basement”. You can appreciate one set of circumstances leading to a failure while strongly condemning the other.




uk_caver said:


> Assuming the headset electronics don't fail and draw a large current, (which would likely mean the end of the lamp anyway), as cave dave points out, the likeliest reason for the fuse blowing is the cable wearing through, and in that case, replacing the cable is likely to be more of a pain than replacing the fuse.


Perhaps wire failure is the most likely cause of a fuse blow, but think about water or mud in the battery compartment allowing a short, or a sharp rap to the light that momentarily flexes the circuit board, or an inductor whose wires aren’t perfectly coated. I’m sure there are others. In those instances I’d like to be able to take out my pocket knife or anything else handy, pry out the old fuse, remove the spare fuse from its handy holder (a-la [email protected]’s extra bulb holder in the tailcap), and pop it into place. If it blows again, so be it and I’ve got bigger problems to sort out, but if it works I’m right back in operation.


Returning from the land of the hypothetical: The fuse in the MYO is just a fail-safe, maybe put in to cover a particular circumstance, but now able to protect against a much wider set of circumstances, and seems a reasonable solution for a problem that can never completely be overcome. The fact that it further protects me and my headlamp against other unforeseen conditions just seems icing on the cake.


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## noelex (Mar 14, 2009)

tnuckels said:


> None of us really know what efforts Petzl has likely gone through over the years in search of an indestructible cable, just as none of us know exactly what differences there might be between the cabling used in successive generations of the MYO. Looks the same and is the same are two different things. .


IMHO Petzl has gone through the years searching for a cable that is as cheap as possible.


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## Derek Dean (Mar 14, 2009)

An interesting discussion with merits on both sides regarding whether a replaceable fuse is needed. I'm new to the headlamp area so I'm sorry if this has been discussed already, but a Google Search didn't turn up an answer for me, so I'm wondering why the manufacturers don't make it easy to replace the cabling? 

I understand that you certainly wouldn't want it to accidentally become disconnected, but it seems to me that a retaining system could be engineered to solve that. 

So instead of spending time trying to make an indestructible cable, which is kind of like making an unsinkable ship, you simply make it easy and inexpensive to replace the cabling as needed. Seems rather obvious to me, but maybe there is some even more obvious reason for permanently attaching the cable at both ends that I'm not seeing.


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## Alan B (Mar 14, 2009)

Good discussion here, and some excellent photos and logic from tnuckels, the OP. I haven't ordered one of these RXPs yet but it is on my list.

Re-engineering the MYO for replaceable cabling and fuses is taking it out of the target market. This is a medium priced headlamp, not a heavy duty professional device. The cabling is designed to be small and adequate, not mil-spec. The addition of the fuse is a safety measure designed to make the unit extremely safe. Prudence causes us to always carry another light, and to consider the condition of our equipment before use. My experience is that the cable looks fine after years of use, but I can't say anything about the internal condition.

I do agree that using a better grade of cable would be a good improvement, but the fuse is fine. No grade of small cable is going to be perfectly reliable in the exposed situation this cable is in. If the current exceeds a couple of amps and trips the fuse the unit needs to be overhauled or replaced, and this is unlikely to be a field operation for most users. Carry a spare light, it is a lot faster and easier than attempting field repairs.

I purchased a 2A inline picofuses and plan to update mine, but have not done so yet. I suppose I'm living dangerously with Eneloops onboard. One thing I don't do is manipulate the wires needlessly. Fiddling with things can reduce the service life by tremendous factors, so just avoid doing it for better service, and treat the equipment well. I keep my XP in a heavy duty zip lock bag, so the cabling does not get snagged on everything in the bag.


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## uk_caver (Mar 14, 2009)

It's likely to be easier on the production front not to design for cable replacement, since that allows the use of adhesives for waterproofing, etc, and also may remove the need for the casings at one or both ends to be easy to open.

I'd imagine that for most people, the original cable will last for the likely life of the product, so the demand would be small anyway, and would likely come some time after the product launch, likely when it was already obsolete.

Out of the potential cable-replacers, many of the the people with sufficient skill not to mess the replacement up would often be doing replacements already, even without replacement being designed into the lights.

If a light was designed with connectors to make cable replacement easy for anyone, that would increase the price for everyone, and could also introduce potential points of failure, all for the sake of a fairly small fraction of customers.

Also, if cables were designed to be replaced, it's likely that a decent fraction of the people who do wear their cables out would consider that replaceability as an admission that the cables weren't good enough in the first place, and would therefore expect to get the cables for free.


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## tnuckels (Mar 14, 2009)

Derek Dean said:


> So *instead of spending time trying to make an indestructible cable, which is kind of like making an unsinkable ship*, you simply make it easy and inexpensive to replace the cabling as needed.


{emphasis mine}

Ah, *Derek* strikes the nail, squarely on the head.




Derek Dean said:


> Seems rather obvious to me, but maybe there is some even more obvious reason for permanently attaching the cable at both ends that I'm not seeing.


I was thinking about something similar the other day while searching for neck lanyards, many of which now come break-away links in them so that the lanyard comes apart before your neck does, in case you get hung up on something. Likewise, better bicycle manufacturers attach a break-away section at the point where your derailleur attaches so this will give first rather than bend and ruin your frame in a crash. An engineered weak point that sacrifices itself for the greater good of the device, like our little fuse does.

The disconnect point of a user serviceable cable would, for ease of access, need to be on the outside of the battery pack, as well as the lamp head. For some lights, this would probably mean giving up waterproof ratings. Even for Petzl, which only goes for weatherproof, this would still introduce two more points for concern. Aside from water concerns, the more connections you have in your electrical path, the more potential points of failure you have. Too, there is the consideration of additional cost in materials and engineering a system that is secure enough not to fail, unless you want it to fail to save the rest of the unit from additional damage (the thought of my original scenario, not necessarily Petzl’s). Again, all a mater of trade-offs.

Personally, I’d like to see something like this, and most of us would probably be happy to pay extra for something like this. But we are perhaps not the average user who simply use their lighting tools for their intended purposes, and then put them up till next time. We look for reasons to use them, and play with them in between. Strange behavior, this is.




noelex said:


> IMHO Petzl has gone through the years searching for cable that is a cheap as possible


And you may well be right. Find a cable that lasts just as long as the warrantee period. Still, 3yrs is not a bad period of coverage, and if enough fail prior and have to be sent back, it’s going to cost Petzl a lot more than this theoretical “50¢ more cable” and they’ll be more inclined to look harder for a more durable fix.


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## hopkins (Mar 15, 2009)

I'm sure you read the data sheet as I just did and it does not say
anything about auto-reset. 
Its just a simple fuse. Got to correct the reason it popped before just replacing
it or bypassing it in the field with a paperclip(exp) or the melting wires will
drip onto your forehead.

http://littelfuse.com/data/en/Data_Sheets/251_253.pdf


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## kwieto (Mar 15, 2009)

Derek Dean said:


> So instead of spending time trying to make an indestructible cable, which is kind of like making an unsinkable ship, you simply make it easy and inexpensive to replace the cabling as needed.



But this will not fix a problem (!!)

The problem is *not* a broken cable, but that *it may cause you burn* yourself/something.
Changing the cable to the replaceable version will not change anything, because if that cable will broke, still it may cause the fire. And the information that you can easily replace it *afterwards* is not a solace in that case, just because it will be too late.

Image the situation, that you put fresh batteries (NiMH in our case) to the lamp and then pack it to your backpack. Then, during the trip, there is some short circuit in the cable which causes that your backpack is starting to burn out.
The spare cable in your pocket is just for nothing in that case... 
And the fuse is installed to prevent situations as above, as well as good cable should do (or at least decrease the risk).

So IMO the piority should be a good cable which does not need to be replaced, just because it makes less risk that broken cable will hurt you or your equipment.


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## uk_caver (Mar 15, 2009)

kwieto said:


> So IMO the piority should be a good cable which does not need to be replaced, just because it makes less risk that broken cable will hurt you or your equipment.


Unless it's possible to guarantee that a cable can't fail with a short-circuit, it seems to make sense to stick a fuse in the circuit as a preventative against bad outcomes.

If a lamp had a cable which would never fail, even if the lamp was used all night, every night, for the entire guarantee period, and was stuffed in and out of bags every day, that would really suggest that the cable was overspecced, unless the light was a high-end one being marketed as invulnerable.


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## kwieto (Mar 15, 2009)

uk_caver said:


> Unless it's possible to guarantee that a cable can't fail with a short-circuit, it seems to make sense to stick a fuse in the circuit as a preventative against bad outcomes.



This is why I plan to upgrade my Myo with that fuse. As I wrote several posts before, I plan tu use the original V shaped connector which is inside battery copartment, and "for emergency" I will leave the cable enough long to be able to connect it directly if the fuse will blow out.
My way of thinking is: the fuse should prevent the accidential burn when the lamp is not under the control - in the backpack, jacket pocket or even on my head.
Then, when I realize that something went wrong, I can connect the cable directly (as it was originally) even in the field, without any tools or spare fuse - and see if the lamp is working or not.
If the problem was in the cable, I can try to repair it temporarily, and use the lamp (taking more care on it, i.e. removing batteries when it is not used) till I'll be able to make the proper repair by replacing the cable and installing new fuse.

I don't think that making the cable replaceable in the field is a good Idea, mainly because the connectors will make it even more bulky than it is now (too stiff and because of that not lying really well on the thead, in my opinion)


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## Derek Dean (Mar 15, 2009)

kwieto said:


> But this will not fix a problem (!!)
> 
> The problem is *not* a broken cable, but that *it may cause you burn* yourself/something.
> Changing the cable to the replaceable version will not change anything, because if that cable will broke, still it may cause the fire. And the information that you can easily replace it *afterwards* is not a solace in that case, just because it will be too late.
> ...


I wasn't implying that a fuse shouldn't be used. As far as I'm concerned that's a separate issue, so maybe I shouldn't have brought up the idea of a replaceable cable. 

It's just that I'm a fan of modularity, and I can see being able to replace the cable as opening up a whole host of other possibilities. Some folks might want a coiled cable while others might want a straight cable. Likewise, some might want a longer cable to attach a custom battery pack to their belt. 

Anyway, sometimes simpler really IS better, and maybe in this case Petzl has done their research and come up with a pretty good headlamp for the price. It's certainly got me interested.


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## kwieto (Mar 15, 2009)

In that case I can say what the others before - it will make the lamp not competitive in price. I suppose that there is not a very big demand for that kind of cables.
I don't think that producer will make the product modular, just to allow consumers to do their own modifications (because it will not make any profit for the producer).
And if he will offer wide range of accessories, the question is if there will be enough demand to cover the cost of design and keeping at least minimum production of those things.
As the others said, probably this is too low price level for that kind of solution to be profitable.

Just compare the Myo XP and Ultra, which is more modular - but the price for it is 4 times higher.


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## tnuckels (Mar 16, 2009)

hopkins said:


> I'm sure you read the data sheet as I just did and it does not say anything about auto-reset. Its just a simple fuse. Got to correct the reason it popped before just replacing it or bypassing it in the field with a paperclip(exp) or the melting wires will drip onto your forehead. http://littelfuse.com/data/en/Data_Sheets/251_253.pdf



Yes, I did go poking around the datasheets on the LF products that Alan B suggested, and realized it was just a common fuse. Still, this didn’t keep me from wondering if there mightn’t be more sophisticated devices available out there.



uk_caver said:


> I'd imagine that for most people, the original cable will last for the likely life of the product, so the demand would be small anyway, and would likely come some time after the product launch, likely when it was already obsolete. *{SINP}* Also, if cables were designed to be replaced, it's likely that a decent fraction of the people who do wear their cables out would consider that replaceability as an admission that the cables weren't good enough in the first place, and would therefore expect to get the cables for free.



This seems such a simple concept to grasp, given a little dispassionate thought, but there still remain some commenters that refuse to be consoled by this small-small application of logic. 




kwieto said:


> Just compare the Myo XP and Ultra, which is more modular - *but the price for it is 4 times higher*.


_{Emphasis Mine}_

As seems to be the case for most of the truly “bomb proof” headlamps out there. 

ding, Ding, DING … we have yet another winner here. *Kwieto* chimes in with sentiments proving he gets the larger picture here.

Perhaps this headlamp is “expensive” and “high end” for some user’s budgets, but in the scheme of equipment out there, as *Alan B* so aptly noted, this is really just a midrange headlamp, and not meant to resuscitate the dead, win wars, or save the world for Democracy. It’s simply a notch or two above average, might serve well in moderately extreme conditions, but really not much more than that.

That’s simply all that $100 bucks will get ya. If you want more, pony up with the extra funds, and there plenty of other options out there, simply for the asking. 


And so I will give up :hairpull: trying to sway anyone and simply confine myself to furthering the body of information available on this new headlamp.

PAX


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## kwieto (Mar 17, 2009)

tnuckels said:


> Still, this didn’t keep me from wondering if there mightn’t be more sophisticated devices available out there.[/FONT]
> 
> I've found some elements for the SMD montage called "Polyfuses", described as a resettable devices.
> http://www.littelfuse.com/searchresults.html?NN=0:Technology:162
> ...


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## Alan B (Mar 17, 2009)

I have used polyfuses to replace pico fuses (in an updated design). One thing to keep in mind with a self-resetting fuse is that they operate by getting hot and dramatically reducing current. We use them to protect wiring, which is essentially what this purpose is. But the location of the fuse must be able to tolerate their temperature rise.


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## kwieto (Mar 17, 2009)

If it is self resettable (I suppose that simply when it get cool enough), I am not sure if it is a good solution. I can imagine the situation when it will work over and over again: 
broken cable cause a short circuit -> fuse get hot and disconnect wires -> fuse get cool and connects the wires again -> broken cable cause a short circuit...
Maybe putting there a little, one-time working fuse was not a bad idea?​
Anyway, I ordered 2x 1.5A fuses and 2x 2A fuses. I think it will be enough for the whole life of that headlamp.
And I don't plan to buy any Petzl headlamp in the nearest future.


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## tnuckels (Mar 24, 2009)

The Petzl man called me back this afternoon. He confirmed with Petzl France that there is *NO RECALL* on the *MYO RXP*. 

There has apparently been quite a bit of confusion between the MYO XP & MYO RXP models, which units have the safety fix installed, which units use which batteries, and the difference between the “safety alert” that Petzl issued and a “recall”. He said that distributors are having a hard time keeping stock on their reseller’s shelves across Europe. He mentioned a forum in Poland that may have been the source of the errant RXP recall mix-up there, but didn’t seem positive. Stateside things are nearly as tight, with most resellers running out of stock quickly.

We discussed the “flash” phenomena again and he said there are no other cases reported of this, but that he would make note of it for future reference. He thanked me for my interest, feedback, and encouraged me to call him back at any time with further questions or observations. He seemed quite sincere.

I’m still enjoying my headlamp a lot. I took my three sons caving this past Saturday, me with my RXP and them with their ROV 1xAA, and we had a great time trying to reach the far end of Fox Cave in middle Tennessee. When the mud started sucking the boots off the 7yr old’s feet we decided to bail out and head on home.

I still haven’t decided what to do about the “flare” caused by the tab on the diffuser. It mostly seems to bother me when I’m trying to distinguish distant objects. Just give me a few more outings to where my cumulative irritation will overcome my inherent laziness and I’ll take the time to come up with good solution for this.

Outdoor beamshots are still on my to-do list, displaced by other more pressing matters. Better late than never … so the saying goes.


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## hopkins (Mar 25, 2009)

tnuckels - one fix for the 'flare' from the diffuser tab was to coat it with some
opaque epoxy which will stop the light leaking down towards the eyes.

Rough the surface of the tab a bit to help the epoxy stick.

Think this would be a nice factory mod that Petzl could add to the MYO's.


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## kwieto (Mar 25, 2009)

Finally I installed fuse into my Myo. Here you have some photos:

1. Metal joint, with original cable removed from it. You can see the "V" shaped profile where the cable was put and soldered






2. Plastic part of the cap covering the cable and the joint. There is a peg which press the cable into the joint when the cap is on it's place





3. The fuse after installation. I decided to leave it not soldered, it is kept on its place by the peg presented on photo 2. I left the wire little longer than it's needed and wrapped inside it's compartment.
If the fuse blow away, I will be still able to make direct connection even without any tools.





That's all... I used 1.5A fuse.


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## tnuckels (Mar 26, 2009)

That’s a very nice fix for your MYO XP, *Kwieto, *clean and professional looking. And smart to think ahead in case 1.5A is too low and blows during normal use. Kudos to the headlamp doctor …


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## tnuckels (Apr 3, 2009)

I’ve been reading about smart chargers for a while now and thought it best to have one to weed out the weak batteries in my collection as preparation for doing further comparisons here. I bought a MAHA C9000 WizardOne battery charger/analyzer the other day and have gotten some surprising results on the batteries that I’ve run through the Refresh/Analyze sequence thus far. Now that I know there is such a disparity between individual batteries, I’m just wondering about the current measurements and indoor beam shots I did a while back. 
 
In an unregulated light, would it matter if a set of batteries charged to 95% of original mAh specs vs. 70%, given that current measurements and beam-shots are done quickly before the batteries have much chance to fade? If they are all putting out nearly identical voltage readings, the primary difference is that some will simply last longer, or am I missing something like maybe current drawn is dependant on available mAh to pull from?


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## anoncandlepwr (Jul 22, 2009)

Hello everybody, I know, that for you all it will be maybe a stupid question, but I want to know how to open this type of headlamp, without breaking it. I have actually other headlamp - Petzl Myo 3, but it looks to me that the key to open will be similiar(that plastic rings on the sides). Can anyone help me with this problem or just give me direction to another thread. thank you very much


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## kwieto (Jul 23, 2009)

Myo R(XP) is not opening with these plastic rings.
There are 4 screws on the back of the light, easy to find when you tilt it.

I don't know how it is designed with the "standard" Myo.


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## Ralph_S (Jul 23, 2009)

The vulnerability of the cable to repeated flexing (10,000 times?) might stem from the forming of a spring-like coil in the cable. To work, the coil requires some resistance to twisting. The stiffness in this case comes from the insulation, which may be more likely to become brittle than if the inner insulation were more flexible, and free to move within the outer sheath. 

Possible design solutions:

1. Make the coil more flexible, beginning with making the inner insulation more flexible.

2. Forget the coil, which is stiff and does not stretch much anyway.

3. Embed a spring wire in the cable, so the insulation doesn't have to be stiff. 

4. *Put a jack on the light housing and on the battery compartment, for a commonly-found type of plug*, whether telephone handset, power supply, audio, or whatever. (If only one jack is used, put it in the head.) Design the jack so most of the plug goes inside the light housing or battery compartment, for resistance to breaking. Allow the user to select a short coiled or straight cord, or a longer cord for a belt- or backpack-mounted battery compartment. The light does not claim to be waterproof anyway. Modifications would be easy.

I doubt that Petzl chose the cable on the basis of cheapness, for the following reasons: 
1. The light is made of polycarbonate, which is "unbreakable," and is not cheap. 
2. A lot of thought went into the design of the light. 
3. Petzl makes highly-respected mountain climbing equipment, so it is not likely to seek low-quality components.
In fact, I suspect that Petzl over-engineered the cable by making it serve two purposes, both carrying electricity and acting as a spring.


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