Help troubleshoot... DD-P7 ?

[kramer5150]

I am trying to fix a friends KL4-P7-DD. Its basically dead, no light at all with any 4.2V cell.

-Its not the E-series switch/body, I swapped that out with mine and still the light is dead.

-When I hot wire the KL4 (see pic) I get Zero Lumens OTF.

Heres what has me puzzled:

When I ohm across the KL4 B- and B+ I measure a dead short, in both directions. Is this normal for a direct driven P7?

Does the P7 below look cooked? I have DD-nuked P7 emitters before, and they have always turned brown. This emitter looks perfectly healthy.

thanks:thinking:

 

[Lumencraft (Matt)]

Hi Kramer,

Since the light is DD there are only about 2 or 3 things that could be wrong. The first is a broken contact, the second is a poofed led the third is a short.

I have poofed P7 emitters before that did not turn brown. If I am not mistaken the brown comes from over heating, but I have destroyed them with too much current. Almost like the LED equivalent of an istaflash.

I have only modded a couple of these heads, but they are fairly simple. If it was on me to fix it I would take a couple of strap wrenches and unscrew the base from the head. Then do some continuity checks and if you don't have a short but do have continuity, I would try your hotwire across the led from the + - contacts of the emitter.

 

[Al Combs]

I'm not an expert on the subject. That said, I think when an LED blows, it's more normal to be open circuit instead of shorted. My DMM runs on AA's, so there isn't enough voltage to energize the LED. It reads nothing from either direction on the ohm scale. Some other members I've heard mention a DMM that runs on 9 volt batteries will make the LED glow faintly when hooked up the right way. The other direction reads infinite ohms because it is after all a diode.

Did it ever work? Or did it just wake up dead after the mod? As a guess, either the modder didn't realize the LED's heatsink core was common with the anode and glued it to bare aluminum. Or the positive lead is touching the back of the reflector or otherwise shorted. If it's a bad epoxy job, you can test by unsoldering the cathode (the lead with the little hole in it) and measuring from the anode or positive side to ground. If it still reads 0 ohms, it just needs to be re-glued.

 

[Linger]

When I ohm across the KL4 B- and B+ I measure a dead short, in both directions. Is this normal for a direct driven P7?
NO. You should get no reading on a DMM with a P7 (Open circuit not dead short). A P7 measures O.L both directions (I just went and tested this for you). While xpe's will give you a small resistance number (e.g.18.0moh) aross the contacts, a functional P7 show nothing on an OHM measure with my DMM, and the test should have made you wonder if you even made contact with your probes, or suggested that the module you had had a broken solder joint.

Does the P7 below look cooked? I have DD-nuked P7 emitters before, and they have always turned brown. This emitter looks perfectly healthy.
Dead emitters - overheated shows visible deformity from melting - easiest to spot the damage by looking for clean straight edges (yours looks good) Overvolting often shows singed bond wires (yours look good).

Could be an electrical path issue, +'ve trace grounded out somewhere. If the unit never worked, likely Al C. is correct and emitter slug wasn't isolated from the heatsink.
(Did you notice any sparks when you connected the battery to the dead short?)

 

[bigchelis]

The P7 Kramer5150 is fixing was originally built by DarkZero.

It pulled 2.5A off IMR 16340 and I suspect 3A off IMR 18650.

As you can imagine testing for OTF lumens takes its toll on some lights. It is more of a bummer when the lights are not mine

So at least the KL4 P7 DD at one point did in fact work.


Light_____________________LED_____________ Cells____________ Lumens____ Time___5m lux__1m lux (cal)__
KL4 by DarkZero_____________P7 DD_____________1 IMR 16340_________484.6______1 sec_________________________
Vital Gear 1cell body___________________________2.5A at tail__________419.2______30 sec_________________________
__________________________________________________ ______________393.8______1 min_________________________
__________________________________________________ ______________378.5______2 min_________________________
__________________________________________________ ______________366.2______3 min_________________________
KL4 by DarkZero_____________P7 DD_____________1 IMR 18650_________574.6______1 sec_________________________
Fivemega 1 18650 ________________________________________________48 4.6______30 sec_______________________
__________________________________________________ ______________452.3______1 min_________________________

 

[Al Combs]

DZ is the man.:bow:

I guess they do sometimes short as they die.

 

[Lumencraft (Matt)]

Still even if the led is dead, the hard parts of this mod are already done. The toughest part of these IMO is breaking the factory glue seal. Once that is done the next obstacle (depending on the head) is making room for the larger LED. Since both of these are done (unless DZ used glue to reseal the head) repairing it should be a simple inexpensive "out with the old, in with the new".

 

[darkzero]

I will always warranty my work but can't be liable for component failures unless I was at fault. I know this particular head has been through a number of people & is the only KL4 I ever built that was DD at the original owners request. I will still offer to repair it for no charge. If the emitter fried, I can't be liable for it, but I will replace the emitter for no charge if one is provided.

Not much going on in this head so I highly doubt something could have failed unless it was tampered with. Yes I do epoxy the head back together but it shouldn't be nearly as hard to open as it is from SF. In the pics two of dies do appear to be bubbled & darker than the other two, perhaps it's just the pic, can't tell for sure.

Whoever the owner is, shoot me a PM if you'd like & I'll take care of it.

EDIT: or better yet, send me an email to the addy in my profile since I'm not here as often as I used to be.

 

[Lumencraft (Matt)]

That's cool DZ. If all products came with a warranty like that ( I'll fix it anyway even though it wasn't my fault) the world would be a better place.lovecpf Kudos to you for standing behind your work, and for lending a helping hand.

 

[bigchelis]

I will always warranty my work but can't be liable for component failures unless I was at fault. I know this particular head has been through a number of people & is the only KL4 I ever built that was DD at the original owners request. I will still offer to repair it for no charge. If the emitter fried, I can't be liable for it, but I will replace the emitter for no charge if one is provided.

Not much going on in this head so I highly doubt something could have failed unless it was tampered with. Yes I do epoxy the head back together but it shouldn't be nearly as hard to open as it is from SF. In the pics two of dies do appear to be bubbled & darker than the other two, perhaps it's just the pic, can't tell for sure.

Whoever the owner is, shoot me a PM if you'd like & I'll take care of it.

EDIT: or better yet, send me an email to the addy in my profile since I'm not here as often as I used to be.

DarkZero,

Thanks for the offer. The KL4 build you did is freaking awesome and produced OTF numbers I was not expecting at all.

I figured since it was likely my fault that this P7 fried I could make it better for him. Kramer5150 agreed to help me and he is putting in an SST-50 instead.

So, everthing is perfectly well now. It was a good excuse to upgrade.


bigC

 

[Lumencraft (Matt)]

What Light body and cells are you planning to use? Will this one be DD too? The reason I ask is I am waiting on an led for a similar mod.

 

[bigchelis]

What Light body and cells are you planning to use? Will this one be DD too? The reason I ask is I am waiting on an led for a similar mod.

The owner of the light runs it off Vital Gear single cell body..He also has some E-series bodies that can take a single AW 17670.

The E-series 18650 body was mine and that switch broke too. Fivemega said he has extra switches, so I will have to fix that hosts too.


bigC

 

[Lumencraft (Matt)]

Hmmm. I hadn't thought of the vital gear body.

Mine will be an L2 body, but its probly going to have to be bored for 17670. They dont quite fit in this body, and I cant find a driver small enough that will handle 7.4V.