Autopsy Forthcoming-FRIED LED'S

LED Flashlights – General Info
1

First up was my STOCK TN32 that I bought in January of 2014.It lasted 5 days!There was no autopsy. I sent it back to Illumns and they replaced it.

David[owner of Thrunite] was one of the first to chime in. He was very concerned, nervous and reassuring that I would be taken care of. They thought it was an isolated incident and I believe it was.

Here are a few thoughts to how it may have happened:

J.Mac-Holy cow! Looks to me like the emitter die was missing solder under the half that went bad and the heat from that area couldn’t get into the MCPCB.

Vinh-My guess is the LED was not mounted on the heat sink with enough solder paste. I have witness MANY MANY MANY MANY MANY LEDs not mounted with sufficient solder paste from every company.

Without further ado,the picture below:

Next up is the L6vn. It will have an Autopsy! I used it On the trail last night for 10 minutes on MAX. Let it rest for about 7 or 8 minutes. Used it for 10 more minutes on max and that was it.The temp was 62F outside.

This morning I was ready to do a max run time test[planned 5 minute increments] and I noticed what you see in the photo below. Needless to say the test was cancelled.

I hope the reason for failure is similar or the same as my TN32. Either that or a bad LED. I hope it is NOT a possibility that these LED’S can’t take a lot of heat. You modders should know the answer to that. I just take an educated guess using others expertise and experience.

Vinh has ALWAYS taken care of me, is very fair and generous with his time and the deals he negotiates with me!

It could be an isolated incident, a defective LED or a mistake on his part. I do NOT want people on here to bash him. The purpose of this thread is to get your ideas of what the causes may be.

PEACE OUT,Capolini/Wolfdog

2

LED caries

Looks like too much sugar.

That’s what happens with such a sweet light.

3

Dirt/residue on silicone dome (greasy fingers,dust,soldering flux residue etc.) LED dome should be carefully cleaned with isopropil alcohol before final assembly.

4

Not sure what you mean. What is LED caries?

Too much sugar? Do you mean too much of a current boost?

Thanks,.,

5

Its strange the kapton tape is protecting the negative wire. Normally the tape would be on the positive wire.

Normally the body tube is the negative circuit so the reflector touching that wire would not matter. But it definitely matters if the reflector touches the positive and will cause damage.

In saying that, i am not familiar with the driver set up of this light.

6

I would have to agree with Neven, it’s happened to me a few times. You can save it by shaving off the burnt area and rigorously clean it and around the area with alcohol, then run it with out the reflector so you don’t smoke it up. I use a pretty strong alcohol, Dykem lay out dye remover.

Bummer man!

7

It’s a joke (and a good one :+1: ) on dental caries aka cavities.

The LED has a cavity from consuming too much sugar (or in this case, current). :smiley:

8

Doesn’t anyone think that the Two reasons/suggestions which led to demise of the TN32 LED may also apply for the L6vn?

9

My best guess is dirty/foreign material left/embedded in the silicone dome. Any opaque material that absorbs photon will heat very FAST in powerful LEDs. It just takes less than a second to burn the silicone dome. The dark burnt material then snowballing the process, carving down to the phosphor layer. This is common problem.

- Clemence

10

Thanks for ALL the input. :wink:

I have to trust that when it is repaired it will be able to handle the heat that the LED delivers.

I have a lot of modded and powerful lights. the rule of thumb that I was taught is, “When it is uncomfortable or too hot to hold, dial it down.I have always done that when necessary[do not really need to do that in the late fall and winter because heat is never an issue!]

By doing that there is no reason why an LED would fail like this one, unless there was some underlying issues many of which have been mentioned.

11

Thanks very much for this information, I very much need

12

It seems you are fishing for a certain response that have in the back of your mind. Maybe just lay it out here and maybe you will find agreement! Cheers

13

Not at all. I am open-minded and diversified and don’t know the exact answer. It’s just that no one mentioned that it may be for the same reasons that the TN32 Led may have failed. Vinh and Johnny Macs experience and opinions are valued and respected.

They both got fried. I guess there’s more than one way to fry an egg!

I forgot something. You gave me your opinion of what kind of response you may think I am looking for.

What is your opinion of why the LED fried? :wink:

14

I had similar cases with moisture breech, fet turbo mode abuse(some people like to abuse flashlight for several hours on turbo mode), dirt on emitter, bad mcpcb, bad emitter (dirt particle which was concealed with silicone doming procedure)…

In your case looks like reflector aluminum particle fell near emitter and burned silicone.

Edit; that or solder particle.

15

Thanks for the input. Where do you see an aluminum particle? I just see Kapton tape. Your eyes may be better than my 57 year old eyes!

16

You can’t actually see those nasty particles but I presume it happened.

This had happend to me when I was doing final touch - soldering ± contact wires to mcpcb and while it looked fine after minute or two on turbo crater appeared with ruined emitter(mostly de domed as 99% of my builds are de domed ones)…

So I did not seen what particle did that but most likely is was particle from my soldering. Sometimes when you put too much flux something pops so that kind of pops can spread some tiny particles to emitter.

17

I am learning there are many possibilities for the demise of my XHP70.2!

The most important thing is to be patient until my light is repaired. Probably got about 8 to 10 days to wait,it is on its way back to Seattle.

18

Good luck either way and keep us informed. To bad, I bet that L6 has serious power

19

On of my colleagues pointed this out.

Using your phone and enlarging the picture works best.

Check out the photo with the reflector and lens still on. Look at the silver ring that encompasses the LED

At 3 o’clock on the inner most part of the ring you can see a speck which runs from East to West.

At 4 o’clock on the outer part of the silver ring you can see a slightly bigger speck which runs North to south.

Possibly some debris[shavings] from the reflector…soldering flux material or some other small shaving of a foreign object.

No way from the photo to tell for sure what it is. It is something and more pieces could have fallen on the LED.

20

Thanks,It is getting fixed and I am having him put even more heat sinking in. I am sure he will be meticulous and take his time to make sure it has no flaws when he is done with it.