can be many things, unless you have a multimeter to check things hard to guess whats happening
sometimes people burn out the 4.7Ohm resistor by short on the 5V LDO supply somewhere
LDO can be broken
MCU smoked by 8.4V input
I have a multimeter and can check things. I have no LDO on the 22mm TA driver board as I use it with a clicky switch. How can I test if the MCU is broken?
you say you run the driver 2S and not use an LDO?
2S —> 8.4V —> smoked MCU
Yes, if you are using it with 2s voltages then you really need one of the LDO versions of the drivers. Technically you can use a zener diod but frankly I never trusted it after having random issues when doing it that way. I just removed the pad from the last designs.
I use a Zener diode and a 200 Ohm resistor on D1. So I might need to swap the MCU.
4.7V z diode is fine
but still check the voltage on the MCU as first thing
I’m not sure if it applies in this case but I have been having some shorting issues. The solder mask over the vias is a little thin on the spring side 7135’s on my last batch of 17mm’s.
Checking for shorts after building the driver shows nothing. Solder on the spring and negative wire by the fet and its a dead short from the negative wire to ground.
Also the Infineon fet’s are fragile. I’ve popped a couple of them testing with a 5 amp protected cell. Starts off with a faint glow in the led with the light off, gets brighter over time and then it doesn’t glow or turn on any more.
I have build hundreds of drivers with this FET, never had such a problem, my guess is you solder it too hot damaging the internal structure
A short under the 7135’s is possible if too much solder paste was used. A simple way to test it is to remove the 7135’s and see if the short disappears.
Heat could be the root of the problem or maybe the Infineon is more sensitive to spikes and arcy sparky on the gate.
Both of the drivers you built for my cob + xml led pivoting head flashlights (you made the first one two separate channels, I did the second driver) got beat up due to the solder you and I use not getting along. Trying to remove the resulting mess with the solder wick that came with my solder station kit was even worse. The second driver I pulled the fet off to drill out some vias (ended up drilling out the vias under the single 7135 and stacking three of them) and had some trouble soldering it back on. The fet on the first driver started to fail after I dropped the light at work and tore the switch pad off the driver.
The second one started to fail while I was troubleshooting the driver. Wasn’t sure if my changes to Narsil were the problem or if I had a driver problem, the stacked 7135’s were not turning on. I put my meter on diode test and hit the gate terminals on the 3 7135’s. Cob came on for a bit and went out, xml on with a faint glow. Turns out there was some uncooked solder paste under the 7135’s shorting the gate to ground that did not show up on the ohm meter. That fet died before I finished modding Narsil.
The third was on a TA driver I built with lousy solder paste on an under powered hot plate that took way too long to heat up, it started the faint glow thing when I slipped with the meter probe and shorted the fet gate terminal to the fet ground terminal. I got rid of the crappy solder and solder wick and only use the Infineon fets on finished drivers. If there is any chance lead free solder has been used it gets wicked off the pad immediately. If there is much testing to be done I use the fets from Mountain Electonics, I have yet to wreck one of them.
I have started using the 7135’s Lexel recommended earlier in the thread, the ground pad on them has exposed metal across the center of the chip on the bottom.
It never shows a short after building the driver, its after I solder the spring and led negative wire on at the fet. The first thing I suspect is the fet, so it gets reflowed off and then back on again. Then I flip the driver over and do the same thing to the 7135’s, putting them back on one by one and usually accidentally knock the spring out of place.
So annoying, and the extra reflow cycles aren’t good for anything. Two times was enough, now I just leave the 7135 pads with vias on them empty.
I removed the 7135’s on the spring side but nothing changed. Still no light! 
When I get new Attiny25 MCUs I will try to swap the old one.
I adressed that viases below the 7135 ground fin way way back in early 2018 or even 2017, for my designs
I am pretty sure I never used Infineon FETs on drivers with that issue
The problem never showed up after reflow, but it showed up after soldering the LED- to the pad, where also those viases were exposed on the pad
so you push the solder through the wire putting the wire on it
I solder all drivers with Sn60Pb40 paste and Sn62Pb36Ag2 solder wire and recommend using leaded solder to get low temperature soldering
just please stay away from lead free it causes so many problems on hobby use
mixing lead free with leaded solder ends up in sort of crystalized bad solder you better remove completely
Thanks for your goodness. Can you help me answer this question? Which driver can I use for the new version of Convoy L2. I want to use Convoy L2 with LED XHP 50.2 or 70.2. Thank you again
Honestly it would be easier to just get an L6 vs trying to convert an L2 unless you just really like the size.
If you must convert the L2 and want to use a TA based driver design then you will need to make sure that you have the 2 cell tube for the L2 and use the LDO version of the TA driver.
I have been wanting to make a new series of TA drivers that uses my dual FET design for the LDO drivers instead of the 7135’s but I keep hoping there will be some firmware updates that I can incorporate into the process.
Thanks you so much. Right here waiting for you. I have GT mini, FT03, new Convoy L2 so i think i’ll mod Convoy L2 with more powerful and most importantly I like your driver.
I got already a 2S hybrid made with that 2S design
got the driver boards and components here
Wow. It looks great!
Is there a variant of Anduril that may fit this driver?
If not, what would be missing?
Thanks.
you have to modify the voltage read code and mix a BLF GT file with stuff from 2 channel lights
for the small FET also another ramping table is needed as it reacts different than AMCs
Basically build your own config files