Good evening. I soldered on LED’s on the DSP40 pcb this evening. All of them worked except the top left two. I finished cutting the legs on the last ones I soldered, desoldered the two non working LEDs, and plugged it in to insure all except the two I removed worked. All of the LEDs stopped working except the two in the middle, closest to the USB C port. All the switches work fine but all LEDs do not work now except the two I mentioned. I checked all the little diodes and resistors to make sure nothing had come loose or popped and everything looks good. Any ideas as to why all the LEDs except those two stopped working? Please see the pic for reference of the area mentioned:
If you have a multimeter with continuity tester or better diode tester you can ensure if current flows correctly to each diode. This will allow to discriminate the diode or not (and check the forward voltage of the diode if you have a diode tester).
Then check all the resistors that are just before the diode.
And lastly if everything is good check that current flows from the start of the resistor to the end of the diode.
If all is well, then maybe it is the FET (PFET or NFET) that has a problem, or the IO PIN that drives it.
I could not catch were is the FET on your image.
I hope the LEDs are not driven directly by the IO pins, so many leds are too much current to do that this way …
EDIT:
Found the FET, it is U4.
The traces that go to the leds are super thin, maybe check if some have blown during the operation…
Thanks for the recommendations. I forgot that I had an extra pcb. Ended up desoldering everything and soldering it on the new pcb and everything works great.
