# Princeton Tech Apex Mod - Step by Step



## stollman (Jan 31, 2008)

I just got done modifying my Apex, and thought I would share how I did it.

*Princeton-Tech Apex, Spotlight LED Modification*

*




*

*Stock Apex*


This is the technical paper that describes how to modify a Princeton-Tech Apex Headlamp by replacing the stock Luxeon LED emitter (60 lumen rating), with a Seoul P4 LED emitter (130 lumen rating). The estimated cost to upgrade the Apex is $20.00. The estimated time to make the modification is 20 - 30 minutes.

Required Parts:
· (1) Princeton-Tech Apex: $55.00 (Ebay, New Condition)
· (1) LED Emitter:
o SSC P4 Emitter, USWOH (pure white color): $10.00
o SSC P4 Emitter, USVOH (warmer sunlight color): $10.00
· (1) 20mm Reflector:
o Khatod Smooth Reflector for the Seoul P4, 20mm: $4.00
o Khatod Stippled Reflector for the Seoul P4, 20mm: $4.00
o A stippled reflector will provide a more diffused light (less lighting artifacts than a smooth/shiny reflector, but you’ll lose a few lumens in light output)
o You might consider buying (2) reflectors in case you screw up the first one during its modification (see Step 5 below). You’ll need to reduce its length by sanding down one end.







· (1) Arctic Silver 5 High-Density Thermal Compound, 3.5 Gram Tube Price: $7.90







*Required Tools & Supplies*

· Medium Grit Sandpaper (or Sanding Block)
· Dremmel with a small, skinny grinding bit
· Soldering Gun
· Solder
· Small Phillips Screwdriver
· Needle Nose Pliers
· Q-Tips
· And Patience (don’t get into a hurry)

Parts Supplier:
· The LED Emitter, 20mm Reflector, and the Thermal Compound can be purchase from Fred Pilon at PhotonFanatic. You can contact him by email to set-up your order.
o There is a $20.00 minimum order
o They accept *cash payments to their* Paypal 
(account: [email protected])
o Supplier* sales thread on CPF*: PhotonFanatic,
Email: [email protected]


Before You Begin (Comments):
· You may want to use a bench vice to hold the Apex head unit in place, while you work on it. If so, you may want to place a piece of material between the head unit and the bench vice metal parts to protect the head unit from damage. Be careful not to tighten the bench vice too tight (may damage head unit). Note: A bench vice is not required. I did my Apex mod on the basement floor.
· Make sure you have all of your “required parts” and “required tools & supplies” prepared before you begin the modification.
· The stock clear optic and its holder will work, but the Khatod reflector is designed to work with the new P4 Emitter (better beam focus, fewer light artifacts). Whether you stay with the stock optic and holder is a personal preference/choice.
· When installing the new emitter, *be very careful to not damage the gummy dome lens while trying to press the emitter into place. It can be easily damaged!*
· You’ll need to slightly modify the new reflector by sanding down an end to get it to fit (it’s a little long – see Step 5 below).
· Make sure there are no batteries installed in the Apex when you begin the modification
· Read each Step carefully, before you take action.
· Note: The stock clear optic will not fit into the new 20mm reflector

*Apex Modification:*
*Step 1: Open Case*

· Disconnect the elastic headband strapping for the Apex Head Unit (removes an interference issue while you work on the light. Makes it easier to work on the head unit)
· Using a small Phillips screwdriver, unscrew the (1) screw which holds on the backplate 
· Using a small Phillips screwdriver, unscrew the (3) screws that hold together the head unit 
· Open up the head unit












------------> --------------------> ------------------>

*Step 2: Remove the stock Luxeon LED Emitter*

· Remove the clear optic and its holder (they simply pull out)
· The Luxeon LED is not glued or attached to the plastic housing in any special way. The LED is held into position by a clearance fit in its plastic housing, and by the pressure of the clear optic. To remove the LED, gently pull on the red and black wires in an alternating fashion, and wiggle the LED out of its plastic housing. It should pop-out somewhat easily.
· Desolder the Luxeon Led from the wires and remove it












--------------> ------------------> ------------------>

Step 3: Grind off the “old” Reflector Guide Nubs on the Plastic Housing
· *Only do this step if you are going to use the Khatod Reflector, else go to Step 4*
· Using a dremmel and the narrow grinding bit, grind off (smooth) the two small plastic alignment nubs. These are the little nubs at 3 and 9o'clock in the plastic housing around the emitter, which fit into the holes of the clear optic holder. The nubs will interfere with the seating of the new reflector.
· After you grind them off, there may be some small plastic debris bits on the heatsink. You can use a Q-Tip to remove them.







*Step 4: Install new Seoul P4 LED Emitter*

· Bend the ( + and - ) tabs of new SSC P4 emitter “up”. You don't want them to touch the metal heatsink
· Solder the wires to the P4 tabs. *Make sure the polarity is correct (black wire goes to side with the notch or cathode mark).** Take your time!*







· Test the Emitter:
o Install the AA Batteries
o Quickly test the new Emitter to ensure you have it wired correctly
o Remove the Batteries
· Using a Q-Tip, wipe off the “old” thermal paste from the heatsink surface. 
· Add a light, even layer of “new” thermal paste to the bottom of the new emitter.
· Install the new emitter into the plastic housing. Remember to take your time and be patient. *Don't press on the gummy dome on the new LED!*
· Note: the new emitter is held in place by the thermal paste, the clearance fit in the plastic "housing" that surrounds the emitter, and the pressure from the new reflector.







Step 5: Install the new Reflector:
· *If you are using the stock clear optic and holder, you can re-install them without making any changes. Go on to Step 6.*
· If you are going to use the new 20mm Khatod Reflector, then:
o To make the new reflector fit into the Apex head unit, you’ll need sand the top of the reflector (not the base) to shorten it. Below you can see I am using a sanding block (med grit) to sand material off the top of the new reflector. You can use the stock clear optic and holder to help gage the required size, and how much sanding is required. You’ll only need to sand off about 0.5mm. 










o I would recommend turning the reflector periodically as you are sanding to help keep it level
o I would recommend after you make a few sanding passes, you check the reflector size to help prevent sanding it down too short. You want it to be a snug fit between the plastic housing and the front lens of the head unit.
o To remove the dust from the reflector after sanding, it is suggested to swish in some dish detergent, then rinse under a strong stream of running water, shake it off well, spray some Isopropyl alcohol on it and then blow dry.
o If you purchased a 2nd reflector, you have a back-up incase you screw up the first one. Not a bad idea, since the reflectors are so inexpensive.
o Make sure the reflector seats well against the plastic housing. 

Step 6: Reassemble Apex Head Unit:
· Reassemble the Apex Head Unit (Reverse of Step #1) taking care to fit the plastic backplate/heatsink cover *BEFORE* you install the two top screws pictured.
* You’re done, and you have a Killer Light!





Modified Apex




*Comparison Princeton-Tech Apex (60 lumen to 130 lumen)*

*



*
*60 **lumen, 14 paces from wall (stock optic)*

*



*

*130 lumen, 14 paces from wall (new "smooth" Khatod reflector)*


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## Changchung (Feb 1, 2008)

Hi, thanks for share, where you get the SSC P4? Is the new version or the old one??? What about a Rebel Led??? just thinking...


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## stollman (Feb 1, 2008)

The parts supplier is mentioned in the article, toward the top. The emitter is the new Seoul. Don't know about other types of emitters or reflectors. I like the light pattern of the Khatod.


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## grnamin (Feb 1, 2008)

Nice work! What material is the Khatod reflector made of?


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## greenLED (Feb 1, 2008)

Greg, it's a plastic reflector.


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## Sarratt (Feb 1, 2008)

I think this post convinced me to take the plunge.
(although I've never soldered anything in my life)

Just out of interest.... will there still be a high\low ? 
Will the run-time be the same ? Less? More?

Thanks for the step-by-step instructions.

S


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## greenLED (Feb 1, 2008)

Sarratt,
1. Yes, and both will be brighter.
2. Slightly more runtime.


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## stollman (Feb 1, 2008)

It still has a high/low. The Seoul emitter is more efficient than the Luxeon. I plan on using the Energizer L91 Lithium Batteries in it (Amazon, $6.84/4), so I am expecting a bit more runtime than the standard Alkaline. The soldering part was the most challenging step for me, since I don't do a lot of electrical work. Patience is the key.


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## grnamin (Feb 2, 2008)

greenLED said:


> Greg, it's a plastic reflector.


 
Thank you.


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## snoboy (Feb 2, 2008)

Very nicely done...

Which reflector did you use in the beamshot picture?


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## greenLED (Feb 2, 2008)

Quick Q - should I be concerned with isolating the Seoul's slug at all in this mod?


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## stollman (Feb 2, 2008)

60 lumen beamshot - stock optic, 130 lumen beamshot - Khatod
Regarding the Seaoul, I only bent up the (2) tabs to which I soldiered. No other mod to the actual Seoul emitter was done.


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## grnamin (Feb 2, 2008)

greenLED said:


> Quick Q - should I be concerned with isolating the Seoul's slug at all in this mod?


 
Someone reported that the heatsink is electrically isolated so you won' thave to isolate the slug. I put a dab of Arctic Alumina 2-part epoxy just in case.


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## snoboy (Feb 2, 2008)

stollman said:


> 60 lumen beamshot - stock optic, 130 lumen beamshot - Khatod



Sorry, I should have been more specific. I meant to ask which Khatod reflector, smooth or stippled, did you use for the 130 lumen beamshot?


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## greenLED (Feb 2, 2008)

grnamin said:


> Someone reported that the heatsink is electrically isolated so you won' thave to isolate the slug. I put a dab of Arctic Alumina 2-part epoxy just in case.


My turn:

Thank you.


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## HEY HEY ITS HENDO (Feb 2, 2008)

Step 6: Reassemble Apex Head Unit:
· Reassemble the Apex Head Unit taking care to fit the plastic backplate/heatsink cover *BEFORE* you install the two top screws pictured here ....................




..........You’re done, and you have a Killer Light!


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## HEY HEY ITS HENDO (Feb 2, 2008)

excellent post stollman, 
i upgraded mine with a TXOH luxeon, even so the difference was truly astounding !


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## grnamin (Feb 2, 2008)

HEY HEY ITS HENDO said:


> Step 6: Reassemble Apex Head Unit:
> · Reassemble the Apex Head Unit taking care to fit the plastic backplate/heatsink cover *BEFORE* you install the two top screws pictured here ....................
> 
> 
> ...


 
Follow this step and don't learn the hard way as I did with my first Apex. I failed to assemble the body completely first and ended up tightening the screws to the point that they punched though the casing on the other side.  That didn't harm the water resistance of the unit, but cosmetic damage is ugly anyway.


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## Patriot (Feb 3, 2008)

I've been wanting to do this. Thanks for the thorough instructions...


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## Changchung (Feb 3, 2008)

I am going to order some SSC P4 to make this mod and others, my question is, can I have a better or equal results with a CREE, REBEL or K2???


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## stollman (Feb 3, 2008)

Question:
Which Khatod reflector, smooth or stippled, did you use for the 130 lumen beamshot?

Answer:
The type of Reflector used in 130 lumen beamshot - Smooth. The beam pattern is pretty nice. You could always buy a stippled reflector and try it (they are pretty cheap)...then you could decide which is best for your application. As mentioned in the article, you could always use the stock optic too.

Question: 
I am going to order some SSC P4 to make this mod and others, my question is, can I have a better or equal results with a CREE, REBEL or K2???

Answer:
Regarding other types of emitters that could be used in the mod, I guess you could use a CREE or some other type, but I have no experience in those emitters for this modification. The Seoul emitter has gotten good performance reviews from other CPF members, hence why I elected to use it for this particular Apex mod.


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## Gimpy00Wang (Feb 3, 2008)

Good tutorial. I might have to mod my Apex after all.

- Chris


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## Changchung (Feb 4, 2008)

stollman said:


> Question:
> Which Khatod reflector, smooth or stippled, did you use for the 130 lu
> 
> Question:
> ...



Thanks...


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## grnamin (Feb 4, 2008)

The Seouls and Luxeons require no modifications to the headlamp because they have the same form factor. You would probably have to modify the section where the LED sits in order to get a Cree to sit deeper and interface with the heatsink. Here's a bigger picture of the inside with the LED removed:





You'll notice that there's a plastic bracket that holds the LED in place. I guess it wouldn't be difficult to mod that section to hold a Cree.


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## Mark620 (Mar 3, 2008)

I have done this mod to Two Apex lights so far....
one also required extensive case repair...owner is a hard core caver...enough said.


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## YuccaPatrol (Mar 6, 2008)

This is fantastic. I'm a caver and cannot yet afford a Sten-Light, so this will give me the light I want at a price I can afford and also give me something to tinker with for an evening.

One question: would it be possible to share some photos that are a little bit larger? I know it will probably all make sense when I start taking it apart, but I'd like to see some more detail to understand what I am doing ahead of time.

Thanks and I'm off to order my parts!


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## Mark620 (Mar 6, 2008)

YuccaPatrol said:


> One question: would it be possible to share some photos that are a little bit larger?



Forum rules forbid large photos.


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## cave dave (Mar 7, 2008)

There are at least two other threads on Apex mods with good tips and photos. Do a search.

here is one:
https://www.candlepowerforums.com/threads/171344
and another:
http://candlepowerforums.com/vb/showthread.php?t=141392&pp=30


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## Mark620 (Mar 10, 2008)

I took the pictures on automatic with no flash on a Fuji S5100 4megapixel from about 7 feet.
All pictures mus stand on their own and no comparison between pics can be done - it would be meaningless...

All lights have Fully charged batteries...
All Apex shots are of the 3watt led.
All Apex lights have the stock optic unless stated otherwise.
Light listed first is on left light listed second is on right.
Due to file and image size I am only listing links.
Enjoy!

First up Stock Apex VS SCC P4 USVOH modified Apex both on high:
http://cryo-laboratory.com/uploader/files/4/stockVSp4Apex.JPG

Stock stenlight on Turbo VS SCC P4 USVOH modified Apex on high: 
http://cryo-laboratory.com/uploader/files/4/stenturboVSApexP4high.JPG

Stock stenlight on high VS SCC P4 USVOH modified Apex on low: 
http://cryo-laboratory.com/uploader/files/4/stenhighVSapexp4low.JPG

Stock APEX on high VS SCC P4 USVOH APEX on Low:
http://cryo-laboratory.com/uploader/files/4/stockhighVSp4low.JPG

SCC P4 USWOH APEX with 20mm Khatod Smooth Reflector reflector sanded down to fit VS SCC P4 USVOH APEX with stock optic:
http://cryo-laboratory.com/uploader/files/4/P4refVSp4optic.JPG

NSS # 55638


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## HEY HEY ITS HENDO (Jun 24, 2008)

....... Very nice comparison mark!


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## DragonFlame (Jun 24, 2008)

So which of the 2 approaches gives a broader beam (sidespill and all) ?
The reflector or the optic ?


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## mountainpenguin (Jun 25, 2008)

any one swapped the 4 led's yet ?
would be interested in getting more light from them as well


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## Changchung (Jun 25, 2008)

mountainpenguin said:


> any one swapped the 4 led's yet ?
> would be interested in getting more light from them as well



Right now is out of stock, but you can try replace them with this

http://www.dealextreme.com/details.dx/sku.12270


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## Mark620 (Jun 25, 2008)

DragonFlame said:


> So which of the 2 approaches gives a broader beam (sidespill and all) ?
> The reflector or the optic ?



the optic


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## luschnouar (Jun 26, 2008)

What kind of LED´s are the four? Power, current,...?
Does it give a datasheet or something?


greetz Stefan


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## Changchung (Jun 27, 2008)

luschnouar said:


> What kind of LED´s are the four? Power, current,...?
> Does it give a datasheet or something?
> 
> 
> greetz Stefan



Their are 5mm Leds, must be 3.6 volts 20ma each...


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## luschnouar (Jul 4, 2008)

does it give some led to replace the four, to get it also a bit brighter?

and after the modification to a p4, does the lamp still work with rechergeable Ni-mh batterys (Sanyo eneloop)???? 

sorry for my english, because its not the best


gretts stefan


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## kuprith (Oct 6, 2008)

yes,thanks for the posted pics.


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## Chads93GT (Mar 5, 2009)

Hey guys, new member. Was researching on upgrading my apex on the NSS site and I was directed here. Is this upgrade still good or is there a better one? I have 3 80 lumen apex's. 2 are new and never used, 1 i use every weekend. I wanted to upgrade one of them and I am searching for the most powerful method. Any input as if this is the best way to go? I just dont want to do it if there is say...........a 150 lumen alternative, hehe. Thanks


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## greenLED (Mar 5, 2009)

:welcome: Chads!

If your headlamps have the Luxeon emitters, then swapping those for a SSC P4 would work great.


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## Chads93GT (Mar 6, 2009)

Well they are all new apexs................soooooooo I would assume so right? Mind defining what you meant by that? haha thanks1


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## NoFair (Mar 6, 2009)

Chads93GT said:


> Hey guys, new member. Was researching on upgrading my apex on the NSS site and I was directed here. Is this upgrade still good or is there a better one? I have 3 80 lumen apex's. 2 are new and never used, 1 i use every weekend. I wanted to upgrade one of them and I am searching for the most powerful method. Any input as if this is the best way to go? I just dont want to do it if there is say...........a 150 lumen alternative, hehe. Thanks


 
Fred has the best ones:

http://www.cpfmarketplace.com/mp/showthread.php?t=180654

They are a bit more expensive than Dealextreme, but they have a warmer tint (not blueish) that works better outside. They are also the brightest on the market at the moment.

You might see 150 lumen with these, but small differences in brightness are hardly visible anyway.

My modded ones seem a bit brighter than the 130 lumen version from Princeton Tec

Sverre


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## Chads93GT (Mar 6, 2009)

Yeah, 150 lumens would be a huge difference in my current 80 lumen output. Im sure all the guys I cave with would be blown away, becuasee as far as i know they all have 60 watt models, as they have much older apex's. Guess ill keep this a secret till then


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## NoFair (Mar 7, 2009)

Chads93GT said:


> Yeah, 150 lumens would be a huge difference in my current 80 lumen output. Im sure all the guys I cave with would be blown away, becuasee as far as i know they all have 60 watt models, as they have much older apex's. Guess ill keep this a secret till then


 
I was thinking small in difference between 130 and 150 

My modded ones are a bit brighter than the 130 lumen ones from PT. 

Sverre


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## Chads93GT (Mar 26, 2009)

Ok I have a question. I have my apex apart, 80lumen model, and I am going to be modding all 5 lights on it this weekend (I hope) anyway i have it apart and I took a copule pictures becuase I can't get the circuit board off of the housing. it appears that there is a little,......diode?? melted into the plastic housing near the spot light lamp, and glued into place. You can see the 2 prongs coming up and holding the circuit board in place. 







Now I can move the circuit board, as its just sitting in the little prongs that hold it in place, it just wont pop out and the only thing I can see holding it down is this little diode thingy. 

Do i have to melt the soldier from these 2 points to be able to remove the entire board, so i can replace the 4 LED's??? I'd appreciate any guidance. Thanks.

Edit:
Nevermind. I used a pick to chisle the "glue" from around the diode and the whole thing popped apart. i got the 4 led's out easliy enough but it was kind of a pain. I need a mini vice or something, heh


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## greenLED (Mar 27, 2009)

IIRC, that's a thermistor.

You only need to remove the emitter (secured in place by the black plastic tabs around it), not the whole thing. The thermistor can stay in place.


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## Chads93GT (Mar 28, 2009)

Well the problem with that is im changing ALL lights, not just the spot light. but I got it figured out none the less. I picked the glue off that was holding it down and the whole board popped out.


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## Gonzo (May 3, 2009)

My diode or thermistor shown in the post by chads93gt is broken (physically cracked in half) and the headlamp will not turn on. Can anyone help me determine what the part is so I can get a replacement?


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## greenLED (May 3, 2009)

Are thermistors color coded just like resistors are?

I wonder what would happen if you simply solder a piece of wire in place?


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## Changchung (May 3, 2009)

This is a diode zener, their come in WATTS, This is very small, you can try with a 1n914 click to check the pdf sheet, the diode zener dont work like the resistors and dosent have color code like the resistors had, the diode zener in this case is use like a swith, when come so hot the zener close the circuit and the light turn off, if you put a wire this feature be will avoid.


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## greenLED (May 3, 2009)

There you have it; listen to those who really know their electronics.


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## Gonzo (May 5, 2009)

Thanks for your help, but I think my Apex is totally fried. It got wet inside because the case was cracked (poor plastic quality). I took it apart to let it dry out, and it will not turn on. Even the battery indicator light will not light up. I even tried putting a jumper across the diode (since it is cracked in half) but no luck. I don't have the original package, so I don't think they would even warranty it. I have had it for about 3 years.


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## NoFair (May 5, 2009)

Just send it in, don't think they need the packaging.

Their CS is good and they know about the cracked housings.

Sverre


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## greenLED (May 5, 2009)

Ditto - what NoFair said. The battery hinge on one of my Eos cracked, and they replaced the entire headlamp, although it was well used. Great CS.


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## Mark620 (Sep 14, 2009)

APEX Cable Gland:


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## Gonzo (Sep 30, 2009)

*Update*

I sent the Apex to PT, and the sent me a new one about 2 weeks later. Excellent customer service. (The old one was cracked, and had gotten wet inside, and was about 3 years old).


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