[HELP] GMMK TKL RGB LEDs flickering

[Musashin]

Hey all, picked up this board second hand, plugged it in and a couple leads are flickering and a few more are not responding properly to software changes. The flickering ones continue this behavior even after all other leads are turned off in software. Any luck for me to solve this? I disassembled the board after the example video was taken and couldn't identify any specific issues on the leds themselves.

[yui]

i have not checked, but it seems that:
-those are addressable LEDs
-there is a bad communication with the microcontroler
if you could get us photos of the PCB we may be able to help a bit better but if my above assumptions are correct i'd check if shorting the data in and out of the flickering ones brings some of the non working ones back to life, and if so the fix would be to replace those LEDs or remove them and apply a bypass wire instead (although doing so will confuse the firmware and so rainbow and key-press effects will no longer line up correctly) without seeing more of the board it will be hard for me to help you more.

[Musashin]

I will definitely get some photos of the pcb put up! Thanks for your suggestion!

[Musashin]

i have not checked, but it seems that:
-those are addressable LEDs
-there is a bad communication with the microcontroler
if you could get us photos of the PCB we may be able to help a bit better but if my above assumptions are correct i'd check if shorting the data in and out of the flickering ones brings some of the non working ones back to life, and if so the fix would be to replace those LEDs or remove them and apply a bypass wire instead (although doing so will confuse the firmware and so rainbow and key-press effects will no longer line up correctly) without seeing more of the board it will be hard for me to help you more.

Hey, I have attached photos of the PCB in total and focused on the affected area.  TBH it all looks OK to me but what do you think?

[Darthbaggins]

Hey all, picked up this board second hand, plugged it in and a couple leads are flickering and a few more are not responding properly to software changes. The flickering ones continue this behavior even after all other leads are turned off in software. Any luck for me to solve this? I disassembled the board after the example video was taken and couldn't identify any specific issues on the leds themselves.

Sounds like you're finding out why the previous owner was getting rid of the board. 

[Musashin]

I'm not too mad.  Got 110x Zealios v1 65g out of the deal so I definitely made out to the positive vs the value of those switches.

Any thoughts on salvaging the PCB?

[yui]

i had hoped to recognize the LEDs as WS2812 and so would have been able to tell you what to short but it does not look like any form of them i know of you could try and see if you have 5V across what should be the power pins on a WS2812B i marked red and black (should work on any of the LEDs on the board, when the board is powered)
if you get 5V across it likely mean it is a WS2812 so shorting the 2 other pins should bypass it and let the other LEDs work, and replacing it should be possible.
edit: should add the datasheet i used: https://www.digikey.com/en/datasheets/parallaxinc/parallax-inc-28085-ws2812b-rgb-led-datasheet

[suicidal_orange]

There are vias in lines that would connect the same pin of most of the LEDs in the closeup and I found a review video showing an instant change of colour across the board so I'm pretty sure these are conventional LEDs with a pin for R G B and 5v, can't be sure of which is which though.
Edit:I am not an LED expert, yui's experience of WS2812's is different to mine so invalidates my thoughts.

[yui]

what led me to think about addressable is the pink flicker when all others are off and that part of board does not light up, it would align with a dead chip in the string that chip displaying garbage and stopping communication with the ones down the line.
but never saw them in that particular form factor and i do not know if the GMMK has individual LED control (if not addressable makes no sense whatsoever)
and if it would be RGB with common positive i would guess the 5V would be the silk-screened + in the bottom-right corner of all of them.
(and i thought the WS series waited for the end of transmission to change the entire string at once but i may be wrong, looked at them maybe 4 to 5 years ago)