Absolutely 
Doesnât turn on, tried P2 & P3.
Any ideas?
Measure ohms between LED- and ground.
5.5 ohms
Well there's a tiny bit of difference between 'doesn't turn off' and 'doesn't turn on'.
Have you tried grounding the MCU pins 2 or 3 directly, not out at the SW pads?
If you temporarily jumper between LED- and ground, do the LEDs turn on?
Can you post both the source code you used, and the exact .hex file you flashed?
Do you have battery voltage (or close to battery voltage) on MCU pin 8? Ground on pin 1? If so, do the LEDs turn on when you jumper between MCU pin 8 & pin 6?
Double check diode (D1), might be in backwards
This was the problem, thanks.
Unfortunatelly, now it doesnât turn off :weary:
The components were purchased from Richard, I didnât flash anything.
If I recall correctly, I also sent you some other 15mm & 17mm driver kits. Is there any way the MCUs got mixed up between them? You can try to cycle modes by quickly cutting power like you normally would with a clicky switch to check.
Everything looks right in your picture, except for the backwards diode which you've already figured out.
Iâm thinking of upgrading my SRK with this FET driver from RMM and am wondering what sort of max amperage I could expect out of 4x NCRB cells?
If I should expect 3A draw from each cell than this will be well worth the upgrade. However if I need to order 4 new high drain batteries to get anything over 8 amps than I wonât bother.
It will do more than 8 amps into 3x LEDs from just a single high drain cell.
Is that implying that I need to buy at least one high drain cell to get over 8 amps? 
Although 4 high drain cells are better than 1 (obviously).
The point is that I already have heaps of button top NCRB cells and would rather
not have to buy new cells to get at least over 8A.
Four non-high-drain cells in parallel will have less sag/higher current than any one single high-drain cell.
I want to put this driver in a sky ray king with 4 LEDs. I donât have much experience with the tecnical side if drivers. What would some recommendations be for installing this driver In? I would also want it to be just a matter of trimming tabs connecting ± to led and switch wires then bam 7 well spaced mined with a nice moonlight and high high.
Hello,
I will mod my SkyRay King 8x Cree XM-L T6 flashlight with a new driver board.
Is the âBFL SRK FET Boardâ a constant current board? Or decrease the LED current then the accu voltage decrease?
Best regards from Germany.
This is the case: âdecrease the LED current then the accu voltage decrease?â
EDIT: Please see this post by lagman or my elaboration on that post (#55) for more information.
Ah ok very interested post. Thank you very much. I think the 32x AMC7135 linear driver is better for me.