A little mod to a Trustfire TR-J10 - Finished. Beam shots in Post #1

I got this light in the mail today,

the SST-90 that I got from ebay for $14.50. I was worried if it would be ok for that price and I was right! It has some dings and nicks and it DOES NOT WORK! Oh well, you win some, you loose some. BUT... if the led is ok, it's still cheaper than buying a SST-90 led. So, I didn't feel too bad and as I looked it over, it seemed it was all about ground, or lack of it.

Well, you know me, I went ahead and tore it down to mod it. Heck with it, I would do that even if it did work!

Here's the driver. It looks like it might be a genuine TF driver.

Here's the important side, the side where I will play with resistors. It sure looks like someone already played with it. That R300 looks like it should not be there. A little small for the pad spacing, but possible it was done at the "factory"...

But, when I got to the led, look at this crud! What the heck is this? I guess it's supposed to be the same thing as thermal paste, but I can tell you, it was working as a fantastic isolator. It's way too thick to do anything at all, except let the led get hot fast.

There was a copper star in it though, so that's almost a good thing, except it's not direct to copper, so it's not much better than aluminum.

Hey, where the heck is the led??

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The SST-90 is now on a much better star. Yes you can reflow an SST-90 to an MT-G2 star. The center pad is just about perfect and the outside pads are close enough to work.

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Now, why did they have that huge "thermal pad" in there? Here's why.

There is a divot right in the center of the led shelf and it's raised all around it, so the star is not making any contact to the shelf. I guess they thought the pad would "take up the slack". WRONG!

I don't have a great fix. It needs to go to a lathe, but I did figure out something.

I cleaned off the high spot, drilled out the divot and pressed in a piece of copper. At least the star will sit down flat, once I smooth it all off.

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Let's talk about power. This light is designed for 2x26650 batteries. I thought it would put out at least 5 amps or so. WRONG! I set up a test station with my meter in line between the driver and the led. Stock, the driver gave 3.2 amps on high. WTH? Well, I guess it's a safety thing. It won't heat up fast with low amps... So, knowing absolutely nothing about figuring out resistors, (I know I have been told before how ot, but it just does not sink in any more... sadly), I decided to just jumper the ones there and see what I got with no resistance in the circuit.

Are you ready? I am using two of those Sony US26650VT cells here, can you guess?

On high I read 15 amps! Oooops! Of course, it only lasted a few seconds and just as I was letting off of the negative terminal, the led went out. NOPE, it did not fry, the wire came off the terminal - the solder melted and the wire fell off.

OK, so I don't think that will work... I removed the jumpers and started playing with the resistors I have, (which are few and all the wrong ones). I never got it where I wanted it. I got to about 7.75 amps, (I am shooting for 10 amps) or I got to 12 amps, but never where I wanted it. I finally got frustrated enough and confused enough, to just settle on 11.2 amps. Yep, that's a little high... or is it? I can tell you that the led never turned blue, never failed, never flickered or looked off color. I think I will attribute that to the Copper star. I also think it's one of those lights that you don't want to leave on high for very long at all.

So, I will try to finish the build by this week-end. I think I will probably use smaller wire from the driver to the led, to add a little resistance.

More when I get more done......................

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It's done and here are the final shots.

One of the biggest issues was the reflector. It has such a huge flat spot on the bottom, that there's no way thick wires can go on the star, or the reflector will not seat far enough. It is one of the reasons I ended up using 22ga solid teflon wire. The other reason was to calm down that 11+ amps, which the light just cannot handle. There's no real meat in the head and it would just be a mistake.

I did drill and tap for two screws, but only so I could squeeze the livin heck out of the star, so there would be minimal AA compound in between. I took the screws out after, since they just stick up too far for that reflector.

The original problem with the light not working, was that the driver was not grounded. It was too tall in the driver pocket and was actually held off the step inside. I ruined the original brass hold down ring, to get it out, so I made two copper rings. One to go under the driver and one to go on top. That way the driver clears and is grounded well.

One ring below the driver,

One ring above the driver. I also used a heavier spring and a lot of copper braid, to take the heat of the amp draw.

All done and right now it reads 8.6 amps (tail cap reading), on high. That is much more reasonable than the 11+ amps it was doing. I believe the 22ga wire had a lot to do with cutting sown the amp draw. The tail cap spring has also been braided.

Beam shots in Post #1.

Warning to all. This flashlight will not be safe to turn on high unless placed in liquid nitrogen for cooling.

Better wear oven mitts too. >)

Wow! That should put some light out there.

I can not believe the price you got that light for though. Quite a coup. Looking forward to the glam shot already :-)

Who says you can't turn a sow's ear into a silk purse?

Nice, I see that light around quite a bit and would love to pick one up for that price. I didn’t know you could put an SST-90 on a MT-G2 board, thanks for that. I have a couple de-domed ones laying around. Now I might just get to playing with them.

Have you considered de-doming that emitter? It really does help throw a ton and they are super easy to do. Let it heat up and it will pull right off.

Looks like another very cool mod.

Whoa, you turned a tame light into a monster. very nice mods.

I’d perhaps suggest more a monster fire breathing dragon.

looking forward to the beamshots

Finished, last shots in the OP and beam shots in post #1.

I’m sort of opposed to de-doming anything any more. Only because I have ruined every one I have tried. I will leave it to better modders.

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Great thread man. Read every bit of it and enjoyed it!

I must say that after you went li-ion your mods are becoming quite insane. I love it :-D

Great work O-L.

Nice. Tail current of 8.6A x 4V x 2 cells = 68 watts - small wonder it gets warm. 8)
What kind of run time do you get on high?

I know the feeling :frowning: I’m 0 for 4 trying to de-dome MT-G2s. Mind you if the 90s are easy might have a go with one

Sunglasses are required! 8)

Awesome mod OL!

About 2 minutes before it gets so hot you can’t hold it. Don’t know the run time on high, since I feel it gets so hot, it needs to be lowered.

Nice!