Well this one is completely new to me, so I’lll share in case anyone has any ideas…
Just powered up a newly installed 2.2 board without the SD card, and as well as the “SD card not found” message starting, I suddenly got a loud buzzing noise from (I assume) the speaker. Hit the kill switch immediately, went round with a test meter again in search of a short, couldn’t find any, and now the board seems dead when I power it up.
Master metal chassis, lots of accents. The loose board was programmed in advance and all seemed fine. I ran all the wires in up to the point where the tails are just waiting for the Proffie to be wired up. At this point I tested every accent LED and the speaker using my little test rig (see photos at DropBox link). All worked fine, apart from that colour discrepancy I mentioned the other day.
Soldered the Proffie up today, tested with a meter for shorts or anything else untoward. All seemed OK, so I fitted a battery and applied power. Buuuzzzzzzzz! Switched off. Checked everything with a meter yet again. No obvious fault. Powered again, but this time it was completely dead.
So now when I power the board, I get no boot sound and no lights. I get the correct battery voltage at Batt+ and Batt- pads (4.1 volts from fully charged battery). I also get 3.3 volts at the 3.3 volt pad, the SD pad and the two switch pads - Just no sound, no lights and no response from buttons
Tried connecting USB and Arduino can see the board, but Serial Monitor it seems can’t. No boot or lights from that either.
I guess my question is, is there a component on the board than can cause this and/or fail like this, and if so can it be replaced? Or is the board toast?
I hesitate to say it’s a bad board because it’s never a bad board (it came from KR Sabers so is a reputable supplier) so my gut tells me it must be something I’ve done, but I’ve checked and rechecked everything else and I can’t find anything else wrong. And the fact that I tested every accent circuit with another board (i.e. my test rig) before I wired the main board also seems to suggest that the board is at fault. Either way, I need to nail it down before I fit another one, hence I’m throwing it out to the learned folk here.
Any thoughts welcome.
Thanks as always.