Fenix TK61 teardown and mod thread

Sensing resistor, okay 1/2 watt, ;)

Excellent pictures! I always enjoy watching pictures like these. And showing the internal parts of the expensive flashlight is highly appreciated. Thanks

Thanks alot for the help!

Now i need to know some things,

1. how do you take of the bezel on top? can it be broken if you apply too much pressure with hand? on which side clockwise do you push?

2. Does the contact board take of easily? any tips? do you take it off with screwdriver by applying pressure on both left and right side slowly, step by step, or one is enough?

3. Does the contact board looks the same - its glued in the same way like on the TK75? (my friend will be modding my 75 as well) what if its glued to strong? :frowning:

4. Dedoming, gasoline vs Nitro-Thinner?

Thank you so much.

1. Mine wasn't glued, but was tight from the factory. I used some rubber strap wrenches, but you could probably do it by hand if you were determined enough!

2. I very slowly worked it loose from each side with first a very fine screwdriver then with a larger one.

3. The contact board is just glued in, although I've never seen a TK75.

4. Never used nitro thinner, just gasoline and the heat method. I can imagine that there are some solvents that would also hurt the phosphor, but I'm not sure which ones would.

Thanks alot, so by hand its possible to “unscrew” the top bezel (the stainless steel part -just to make sure we talk for the same part) on which side do you rotate it clockwise to unscrew?

Yes, the stainless part. It is threaded normally (RH) so screw the stainless part counter-clockwise.

Thanks so much!

Fresh gasoline, in a warm environment, seems to work best for the de-doming. I just drop it in overnight (making sure it’s sitting dome up) and in the morning if it hasn’t floated off it pops off easily. I use a toothpick to pop it off if necessary, from the negative side. Then use the toothpick to clean any remnants off, making sure to leave the bond wires strictly alone. I rinse with de-natured alcohol to cut the gasoline smell. It evaporates cleanly and is dry within minutes.

I typically use an XM-L2 U2 1A, but even those sometimes have a bit of a green hue to the tint when de-domed. A trade-off, it would seem, to the doubling of throw. If anyone knows of a specific emitter that de-domes to a neutral white or a technique that allows the same, I’m all ears…

Dale, lately I've been moving towards the hot dedome method. This is purely anecdotal, but I seem to be getting slightly less green shift with this method. More risk, but perhaps more reward. I have killed a few emitters doing this, but Lisa couldn't put up with the smell anymore! Our apartment makes things difficult sometimes, and even though I try and do almost everything outside, some smell always makes it in.

I'll post full details tomorrow if all works out, but I've got mine cranked up to 5.8A to the emitter now. There is no way the stock driver MOSFET(s) could handle this kind of current, I have a few burned fingers to prove it! (low tech thermometer! ) If it survives a few 10 minute runs on high, I'll post details here. I also have a stock light to compare it against and get some readings from (lumens, lux.) I put the stock emitter back on the stock MCPCB, so the two lights will be equal in that regard.

Both the hot de-dome and the 5.8A. Will be watching closely…

Hot de-dome at time of re-flow? I heard that a med firm press on the dome right after re-flowing the emitter makes it pop right off. Haven’t tried it.

Some of my best dedomes have been accidental!

Here's how I do it (very similar to Vinh's method on Youtube.)

1. Heat emitter until solder flows.

2. With a sharp knife, quickly cut the corners and end of the base of the dome opposite the bond wires.

3. Reheat until solder flows again.

4. As soon as solder solidifies, take your knife, slide it under the dome, and quickly pop it up and away from you (towards the bond wires.) If you do this while the dome is still hot enough and with enough precision, you will have a nice dedome. If you don't, you will have potentially lost phosphor, broken bond wires, or a dome left partially in tact. I have killed a few emitters doing this, but have been mostly successful. XP-G2s are much more difficult to do this way since they are so small!

There is a bit more risk involved with this method than with the gasoline method, but some may feel the tradeoffs are worth it.

Please post back, eager to know!

:party:

Fingers crossed you get it to work.

Since the TK61 have two buttons. Could use one as a mechanical power button and the other for electronic switch. :)

:beer:

:beer:


@RMM looking forward to hear more about your progress. Will you stop experimenting if you get it to run reliable for 10-15m at 5,8A?


Regarding Dedoming. Could we keep that to one of the many threads that already started?

One of the relevant threads, and a video too.

A Perfect Dedome?


I noticed on my lights that the MOSFETS around the resistors looked a bit melted. Id guess its because I held the solder iron too close when playing with the resistors. Or they have seen too much heat when I did some indoor runtime test. Its recommended to use thermal pads. I don't use that on my light simply because I want to see how the driver handles it without. J)

WOW i can’t imagine anyone run this light 15 mins perma on turbo, isn’t it too much for this modded lights?

I never run more then 1/2 mins max on turbo, even on stock…always circle around the mods.

lol.. 1-2 minutes? On a light of this size thats only running a few amps.

Unless a light can be used until its uncomfortable hot its no good IMO.

My hottest light (so far) is my hotrodded tintmixed/widespecturm 30+ amp 9-XM-L fandyfire. The front of the head can reach about 140C/280F in around 15 minutes. I wont dare to think how hot the 12 XM-L light pictured in OP could become once that is pushed way harder. 0:)

My first runtime test after I resistor modded the TK61 was around 15-20 minutes on Turbo. I just did another one at 30 minutes. Indoors. No breeze. Tailstanding. Quite hot indoor temperature. Gets uncomfortable to hold after around 15-20 minutes. Too hot for me to hold after 30 minutes. Outdoor I would expect it to run from full to empty batteries on Turbo without issues.

Again, I cant speak about long term reliability, but real outdoor use will never see anywhere near the temps I get indoors.

But i don’t understand, if you are not professional or some search and rescue, why do you need super mega 1600lm, and like 500.000 cd constantly for 15 mins? for example last night my TK75 was modded to ~ 4400 lumen, or 4.68A (based on some other user measurements with same resistor R015)

The light has become insanely bright, like stupid bright, now compared to before OMG effect.

The light heats up like ~ 40% faster or even more. I was going from turbo > high like on every 30 seconds, i just don’t need constant turbo if its not real need, for fun few mins on max and cycle is pretty good for me…while still having low temps and better relaibility - less pressure on the light.

BTW this lights T (K75/61) have no over temperature protection afaik, so i would strongly advise against testing modded lights in hot rooms without fan……you have no need for that, just a friendly advise.

Some of us want to play with em, have no real need to use em. Others want to be able to put a light to work, and do exactly that. Mostly I play with the lights I modify, I take them walking to take the trash down to the road once a week, a 300 yd walk down and then playing with Turbo and such on the walk back, stopping to compare and test along the way. But sometimes I have need of a light to use, and then it’s from 10-15 minutes to maybe hours. So I like to keep in mind that any light I build may actually be put to work. I expect it to handle that, or what’s the point? I know I’ve modified some lights to the point that the higher levels will burn through the cells too quick to be useful, but am trying to use more levels now so there will always be a position that can be selected for an optimized power/runtime equation.

And such is the nature of the beast. Letting the desire for MORE overpower the actual needs is all to easy. But, a change of scenery can often show that what we’re happy with at home may not be viable elsewhere. A cave, a mountainside where the valley is distant, wide open spaces can devour even the biggest baddest light out there. Large bodies of water do the same.

For me, it’s just finding that I have the ability to push a light to it’s extreme. I’m having fun with it, and right now that’s what it’s all about. :slight_smile:

Yesterday I took my wife shopping form some new black slacks to wear on photography shoots. Carried my MT-G2 Sinner Ti as is now my custom. In a nice store like Dillards, having the MTG2 was very handy, making it easy to see the navy blue vs black. :wink: Without the light, I was getting it wrong under the store lighting. Put em to work…

I understand the need to have a massive amount of light, but now with the mod, my high is like 1600 lumens, so you want to say that that’s not enough for a walk? :smiley:

I know i know wrong forum to say hat buy still :smiley:

Generally i use 400 (now 500 lumens i guess) mod from my regular yard checkups, sometimes i blast full power of 3000 lumens which illumuinate my whole yard, and i can imagine now with ~ 4.400 lolz. Anyway i hope you guys don’t get me wrong, i love massive output lights, but just i’m used to cycling trough modes, and no that’s not to preserve the lights, its just an habit, don’t know why i do that :slight_smile:

We have some pretty awesome storms roll through, and with the fast growing Hackberry trees on fencelines (courtesy of the birds) we routinely have a large tree down from high winds, and usually across a road out in the country. We don’t wait for the County to come clear the road, but voluntarily grab up the chain saw and clear the way. My 5000 lumen M6 will be great for lighting up such a scene, but will it last for the hour or two it’ll take to cut a 28” thick tree into small enough pieces to clear the road? Maybe still in the rain?

Repair a fence after a drunk drives through it and hopefully before cows get out? Black cows? In the night? With wide open spaces easily a mile in length? 1600 lumens isn’t enough. Unless it’s focused like a laser. :wink: [not difficult to repair the fence with lesser light, but finding the cow critturs is another story altogether…]