Need some help from the electronics experts among you please:
I've designed a PCB for the FMC. According to the wiring diagram I've soldered on all the resistors and all the LED switches. I plugged in a 12v power power adapter which I think was 0.7 amps, and all the LED's were flashing, which according to online research, indicated the power supply wasn't enough.
I found another 12v power adapter which was 3 amps and after a couple of audible clicks, all the LED's went out. Turns out half of them have blown (palm on face moment). I removed the faulty LED's, tested the remaining ones work with a tester, replaced the faulty LED's with new ones (tested), but cant seem to get any of them to light up now when I plug in a 12v 1 amp adapter. Tested individually they all work, I have also tested the resistors are fine with a voltage meter.
Not sure what else to try. Any help is appreciated. Thanks!
Hello,
I don't know if my reply is coming too late, and meanwhile you already sorted it out...
Your problem is rather strange but, looking at the original wiring diagram, I've noticed a naming ambiguity that could have misled you when designing the PCB.
The problem is that all led cathodes have been named "GND" meaning the - terminal, NOT a ground connection! The leds have to be connected in series of four, being only the lowermost led's cathode of each row connected to the actual GND, that is:
[+12V]---[RESIST]---[+led1-]---[+led2-]---[+led3-]---[+led4-]---[GND]
Should your PCB have (just guessing) all leds cathodes connected to GND, this could be the reason of the malfunction you've encountered.