# I upgraded a Myo XP!!



## hirby (Sep 11, 2007)

So I read about how easy it was to upgrade the Myo XP to the Seoul P4. I decided to give it a try with 2 Seoul P4 stars I had purchased from Fred Pilon in the buy/sell area.This is the first flashlight I have ever tried to upgrade. Main reason being that I use this Myo XP headlamp the most, but often wished it were a little brighter. This is my first upgrade of any flashlight type device. 

I also have an old Myo3 halogen/3LED that I NEVER used. Once you get used to LED's, filament lights just don't cut it anymore. Plus the 3 LED's it came with were terrible in color and focus. While the Myo3 was MUCH cheaper than the MyoXP long ago when I got it, it had a MUCH better battery box and strap setup than the MyoXP. Guess what, the Myo3 bracket is the "exact" same as the MyoXP's. Just a different color. Look at the battery box, so much tougher than the regular MyoXP's. Spring loaded water resistant cap, hard shell box..








First I had to both head units out of the headband brackets. Petzl uses these funky plastic one-way screws that remind me of bathroom stall screws. How will I get them off? 










I made a high tech tool out of two nails and a piece of wood!






Just turn the plastic head 180 degrees and it pops loose. I cut the Myo3's power cord off and removed the head unit. Did the same to the MyoXP.

Once I had the MYOXP unit out and apart, I noticed this POS piece of thin aluminum that Petzl considers a heatsink.. In addition, there is way too much heatsink paste in there. Took me forever to get all the excess off (too much actually hinders heat conduction). Once I got the circuits out, I hooked up 4 brand AA alkalines to the unit to see if it would work. Just enough to light the lights up. Didn't want to overheat it since it was apart. Worked like a charm with 4 AA's. All functions worked.

I then desoldered the power wires and the Luxeon. In there place went the new Seoul P4 and the wires to the Myo"3"'s battery box and headbacnd/bracket. A quick test and everything was working.










Knowing I was gonna be driving it hard, I had to do something about the heat. That POS thin piece of aluminum wasn't gonna cut it. Time for the dremel tool! I held the back piece in my hand and using a diamound round bit, took out all the posts and bumps and any excess that was in the way. If I had not intended on making my own heatsink, I would have run into the issue of spacing with the original heatsink. The backplate on the Seoul star was much thinner than the original Luxeon. The posts would have kept the original heatsink off the back of the LED by about 1mm. I would have had to modify the aluminum plate or the posts. Since I had a custom heatsink in mind, I just tore the thin posts off with some pliers.






Then I took an old aluminum heatsink (about 5mm thick) off the southbridge on an old PC motherboard and cut it down to size and shape so it would fit in snugly. I first cut the sides so it would slip in, and then I ground it down little by little, until putting the backpiece on squeezed the heatsink very tightly onto the back of the Seoul LED. The tighter it was, the better heat would be conducted off the LED star backing.










Compare the two. My southbridge cut heatsink has much more surface area and at least 5 times as much material volume, even though it looks smaller.






The heatsink has hollows in it and I made a area that the heat sensor would fit into so it would be dead center of the LED area and in contact with the custom heatsink's bottom plate. With a thin skin of silicon heatsink paste (nothing special like Artcic Silver) on the back of the led and on the heat sensor, I reassembled. The heatsink is held TIGHT against the back of the LED so it will conduct heat much better than the 1/16 inch glob it came as.

To get the plastic bracket screws back on, just snap on and then turn until you here a loud 'click" 

Here is the finished product:










Heat sink is working well, I can feel it get warm. If I blow in the bottom drain hole so that the air comes out the back two air holes, you can definately feel hotter air come out. This is good, means the heatsink is conveying heat out of LED. Time will tell if the heatsink can keep it cool enough, but so far seems ok. Light is MUCH brighter. Med is as bright the old high (if not brighter). No color shifting that I can tell. Hotspot is much wider and floodier. 

Just a little heavier, but better balanced with the better headband and so much brighter, especially on the 20 sec turbo mode!


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## Gaffle (Sep 11, 2007)

Wow, really nice post. Great idea utilizing that old Myo 3. Curious, how is the XP circuit is affected due to 1 extra battery?


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## SIMON LEONE (Sep 11, 2007)

that's very impressive to read and to see your photos. 

I really like those mods where u improve stone age lights :twothumbs

that aluminum cooler is awesome ....

any information about runtimes ? 

best regards !!


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## hirby (Sep 11, 2007)

OK, I did a little testing and a couple minor changes. Wanted to wate for the heat sink compound to settle before I took it back apart to mess with.

Here is the completed insides:






Side Shot. Notice the heat sensor is "inside" the heat sink.






For pseudo temp testing, I ran the light with fresh alky batts on high and kept resetting the turbo mode every time it auto dropped (it turns off turbo automatically after 20 secs). I did this for about 5 minutes. The heat sink got hot, but not dangerously so (of course it was outside the enclode case, but it at least gives me an idea of how how it got. I could actually put my upper lip (very sensitive) on the surface of the heatsink without discomfort.

My voltage test with relatively fresh cheapo no-name alkys tested at 6.29V at the input. At the LED on "high" it tested at 3.22V. On Turbo, it tested at 3.4V. This is assuming I didn't do it wrong of course. Good enough for me, nothing too outlandish.. It works, all I care !

With some partially worn alkys, it tested at 5.44V at inpt, and then 3.15V at LED on high and 3.26V on turbo.

For the case, i opened up the already existing rear holes a tiny bit for better air circulation. As the MyoXP isn't water proof anyway, I'm not worried about it. It has worked in downpours without issue, and if I'm in water where the water is higher than the headlight on my head, I'm probably drowning anyway. .






Here are the back holes with it all together. You can see the heatsink peaking through.






On the bottom, I opened up the existing drain hole a little bit too. The theory is that air can better flow from the bottom up out the top (at least it sounds good . 






I am really liking this light now. I like the fact it uses four AA's! It is definately a LOT brighter and I hope it last longer in battery life (haven't tested). I can now use rechargeables in it whereas I used to avoid them for this light. Nothing worse than keeping track of "3" AA rechargeables and an extra since the chargers require "4" in...


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## hirby (Sep 20, 2007)

Update on battery life with 4 AA's instead of just 3. It lasts a LOT longer. I ran for 5 hours on high using cheapo carbon AA batteries (from the dollar store) and it still was brighter than the equivilent medium setting before the mod. I quit at this point because I have never needed to run it on high for so long. On med and low it will last all the longer. 

It is also definately brighter using 4 AA's compared to 3. Can't tell you how much exactly as I have no meter, but as my eyes can easily tell, it has to be a decent amount brighter. 

4 AA's would definately overwelm the stock heat sink with heat, but my custom one is doing great. It gets hot, but has enough mass and surface area to bleed it off into the air (even inside the case). The thermo regulater has never kicked in. I did test that it was still working by applying the flame of a lighter on the heat sink to heat it up and the light got dim as the thermocouple thingy kicked in.

The beam is much more floody than the original Luxeon was and yet is very much brighter (and whiter) even in the hotspot area. No it's not regulated to stay the same brightness, but I actually prefer gradually fading versus instant off for this type of light and the manner I tend to use it. I am VERY happy with the mod!!!!


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## hirby (Sep 24, 2007)

Here's some close up beam shots

Here is a custom Seoul P4'd 3C battery non-regulated Tek-tite (right side) next to my Myo XP headlamp P4'd Seoul (on left) with custom heatsink and 4 AA battery pack (normal is 3 AA).






The Myo Xp has a much fatter hotspot compared to original Luxeon LED and the tektite. It is a LOT brighter than the original LED and also a bit brighter (as judged by my mark1 eyeballs) then the 3C battery non-regulated Tektite although hard to tell by the pic.

For this reference photo comparative to a common incandescent lamp (Surefire P60), the one on the left is a Surefire Z2 with P60 lamp. The flashlight on the right is the Custom Seoul P4'd 3 C battery Tek-tite. All the photos were on the same camera settings.


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## hopkins (Jan 23, 2008)

Cool mod Hirby!
Like the heatsink you made. Gave me some ideas.

For my MYOXP I was considering how to mod the heatsink to dump more to the outside air. Maybe 2 copper screws, altered so that their heads fit flush 
near the thermistor and pass thru the back (drill holes so I could rotate them
in to assure seating is tight once its all assembled) + a bit of therm paste.
Length cut so the bezel tilt is not affected.
Anyway it seemed a fairly simple


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## Phaethon (Feb 10, 2008)

Good job!
However, i am curious about one thing. Petzl does not recommend the usage of li-ion batteries in the myo xp, reporting that several units have burned in the process.... Therefore, how can it work ok with 4 cells???


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## hopkins (Feb 11, 2008)

About upgrading from 3 cells to 4; I think Hirby's heatsink is doing the job
that the stock could not do. The thermistor will kick in on my stock
XP in Turbo Mode to reduce current (w/ 3 right out of the charger NimH AA's)
after 20 seconds. 
And Hirby newer LED into it able to handle the increased current.

I've still got to say that the ergonomics of the MYO XP make it my
most comfortable HL plus being able to flip the diffuser with mittens on
is such a welcome feature when your hyperventilating on a mountainside.


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## Panter (Feb 17, 2008)

Great Upgrade!
Do you know where could I get new optics for my Myo XP? I would need more spill. 
Thanks


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## jezzyp (Feb 20, 2008)

hopkins said:


> The thermistor will kick in on my stock
> XP in Turbo Mode to reduce current (w/ 3 right out of the charger NimH AA's)
> after 20 seconds.



I thought that the 20 sec cut off on boost was standard. On mine I can press it and then just press it again and again.

I tested this when I upgraded my XP, I continually kept pressing the boost and the heat sink never got hot - even after 10 continuous boosts!


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## Phaethon (Feb 21, 2008)

Still, i would appreciate it if someone could provide info on using the myo xp with 3 lithium cells.........:shrug: Does it get hot? Does it get fried???? What happens after conversion?


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## hopkins (Feb 22, 2008)

Hi jezzyp
1.When you say you can keep pressing the boost does the LED in your 
XP dim first then you release the button and press again?
And it comes back on at full brightness for another 20secs then
dims again, and you release the button etc ??

2.Or if not, can you ever get the LED to dim? holding boost down for minutes?
with lithium AA's will it ever dim?

3.You're sure there is lots of therm paste on the thermistor/heatsink contact point after the mod was done?

Curious. 
-hopkins


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## hopkins (Mar 1, 2008)

Never mind! The 20 second boost function is an automatic time-out.
An internal clock countdown inside the circuit. If the thermistor does not get hot
due to environmental cooling you can repeatedly boost.


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## beautifully-stupid (Mar 10, 2008)

Just picked up the updated Myo XP. Boost function only seems to work while the button is being pressed and turns off as soon as released. 

any suggestions on running a separate battery pack from a pocket without cutting the extisting wires?

can you run some power wires to the positive and negative terminals on the battery back, or maybe mod some dummy batteries.

I'd like to run NIMH but have noticed some drop off in output. Another thread mention 4 batteries to work properly. 

Thanks in advance.

B.S.


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## Vicente (Mar 10, 2008)

I have performed the P4 upgrade on original Myo XP and wow!

Thanks for the great pictures :thumbsup:

I would add however that if you are JUST upgrading the LED you don't need to remove the plastic screws on each side of the head. Just rotate the unit forward, and the 4 Torx screws will be exposed. Remove these screws and the front half of the head can be removed for the work to proceed.

I am still refining my own heatsink solution but think I will use "thermal adhesive" to glue it to back of the P4 star so there is no doubt about whether there is contact. Most people are familiar with thermal paste which is non-adhesive since that is commonly used for computer components for which there are mounting clips for the heatsink that apply mechanical pressure. But if you look around you can find a 2-part epoxy which also has heat-transfer properties. I happen to have some Arctic Silver thermal adhesive around because I work a lot with PC and sometimes in those modifications you want to stick heatsinks on chips without factory fittings for them. Makes it non-removable but who cares?

If there were a cheap source of 4-AA packs I would do that mod, but there isn't. Even with the original 3-AA pack and 3 Sanyo Eneloop NiMH "hybrid" batteries it is plenty bright now. Modded Myo XP with NiMH was still way brighter than un-modded TacTikka XP with fresh alkalines in a side-by-side comparison.

I am now going to tackle same modification on this newly-purchased TacTikka XP which has the old LED as well.

I wonder if next year there will be SSC P5 and I can upgrade again


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## beautifully-stupid (Mar 24, 2008)

Vicente said:


> If there were a cheap source of 4-AA packs I would do that mod, but there isn't. Even with the original 3-AA pack and 3 Sanyo Eneloop NiMH "hybrid" batteries it is plenty bright now. Modded Myo XP with NiMH was still way brighter than un-modded TacTikka XP with fresh alkalines in a side-by-side comparison.


 




I picked up two 4AA packs from Radio Shack. One of them has a sliding cover and a switch while the other is your basic flat, 4AA pack. The batteries sit side by side.

I'm looking for a water proof case today so it can serve as a belt/ pocket pack. 

The mod was actually easier than I thought and output is much better than before.


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## Vicente (Mar 30, 2008)

So I upgraded my TacTikka XP with a P4 now also.

It just doesn't seem as bright of a center spot. If I hit Boost I can get it to equal the Myo XP. Is this just the difference in the optics?

Now I'm thinking about the MyoBelt unit. My problem with the standard Myo XP is the big battery pack on the back of the headband. Not only the weight sometimes it just gets in the way like you need to lie down and look at something from underneath.


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## Ozgeardo (Sep 28, 2009)

*Require info on Tactikka XP Mod ?*

Yes Search is our Friend.

Just came across this thread and I am now seriously thinking of giving my Tactikka XP a "makeover". I love (in a bloke type of way) my Tactikka XP, it is just the right size for my primary head lamp in the field, good run time, good ergonomics, good features/modes, boost feature is just perfect for my requirements, it takes AAA which is compatible with my Foretrex 101 GPS, non regulated which means I can recycle my GPS batts into it to get that extra bit of life is required. (I spend about 10 days at a time in the field)

Now if I have read this thread and others correctly (this is were I may have got it wrong):

I can purchase a SSC P4 or ? and with a bit of soldering and following the above tips all should be good. Is it necessary to do any mods to the heat-sink if I only use boost sparingly for a few seconds at a time ?

The upgrade will provide better light with same power use ?

Where can I purchase a SSC P4, considering I need it shipped to Australia ?

Thanks


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## tnuckels (Sep 28, 2009)

I think this thread might be more useful, and there are others floating around as well specific to moding the TIkka XP. It’s old information, but mostly still works. Only difference is that the current SSC P4 *STAR* (LED emitter mounted on *an aluminum* heat-sink) is either U2SW0H or U2SV0H. Color spectrum for SSC can be found HERE.



I did this mod just a few nights ago on one of the two Tikka XP HAZLOCs I bought the other day. I still haven’t got round to finding a small enough Torx bit, but used an Alllen wrench of suitable size to get the three screws out. Steps follow: 

Remove 3 Torx screws
Pushed the lights internals out by pressing on the front lens
Removed the optic and black positioning ring over the LED
De-solder red (+) and brown (-) lead wires and remove LED
Transfer white thermal paste from center *backside* of old LED*'s star* to center *backside of* new LED*'s star*
Position LED with (+) & (-) in correct orientation and re-solder lead wires
Replace black positioning ring with long legs in star’s cutouts and snap in place under retaining shoulders
Replace optic
Replace internals making sure switches slide into place
Replace 3 screws making sure to rotate CCW till thread ends “snap” into place, thereby ensuring you are using the original plastic thread tracks and not cutting new ones, then CW till screws are tight
Replace batteries and cover
Viola, more light
Go with the SSC P4 *STAR* as it is an easy one for one swap with no other modifications necessary.

Mod will provide much better light with same runtimes.

I’ve bought LEDs from these two sources, one in Korea, the other is Stateside. Sorry, don’t know of any Aussie sources.

Good Luck!


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## Ozgeardo (Sep 29, 2009)

Thanks tnuckles :thumbsup: exactly what I need to know

I just ordered 4 U2SW0H SSC P4's. (I just know I will have to mod a few more for my colleagues).

If I have any issues I will yell for help! I am reasonably mechanically OK but electronics has never been my strong suite!

Cheers


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## tnuckels (Sep 30, 2009)

Glad to be of assistance *Ozgeardo*. 

I’ve added a few words, and emphasized a few others, to make the instructions a bit clearer. Though you didn’t say explicitly, I hope you bought SSC P4 *STARs*, and not just the emitter. The mod can still be done with emitters, but it is quite a bit more tedious to swap emitters off the star.

Any questions are welcome. Let us know how it goes.


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## Ozgeardo (Sep 30, 2009)

Thanks again tnuckels , you are making this mod look & sound easier all the time. Yes I did get the "stars" from the Korean supplier, with postage etc I could get 4 for the price of one ex stateside (Usually I prefer to buy ex US but as you have dealt with this supplier before I will give them a go).

Cheers
Ozgeardo


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## Ozgeardo (Oct 6, 2009)

Just received my SSC P4 "Stars" (1 week from order in Korea to my door in Australia  )

Armed with the instructions from various members of this forum I have undertaken my first LED light mod (I don't count drop ins!).

You guys made it too easy  thanks.

My Tactikka XP is now much brighter lovecpf

I have just been doing some comparisons outside with some other lights and I am very impressed.
The modded XP provides excellent white light and flood (without the diffusion lens) and the boost is on par with many of my bigger CR123 tactical LED's 

I usually go through 2 sets of batts on each trek (usually 8-10 days) plus recycling some of my batts from my GPS if necessary. (The plus of unregulated!) I will be interested to see how the SSC P4 goes with the batts. I hope to confirm what I have read here that run times should be similar :thumbsup:

I have several colleagues with Tactikka XP's and I just know that they will want me to mod their XP's (hence why I bought 4 x SSC's). I recon with a bit of wheeling and dealing I can cover the entire cost of my upgrade and postage 
Thanks again to all
Ozgeardo


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