On 22. Jan 2023, at 23:15, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote: On Sun, Jan 22, 2023 at 7:46 PM Andreas Grapentin andreas@grapentin.org wrote:
I removed the RT8288, and now the 5V rail is no longer short to ground. However, I still can’t power the board over USB, I only get around 13mV on the 5V rail. I’ll check around some more and see what I can find. maybe a resistor is faulty.
next thing to check will be the SY6280 which is a current-limiter IC. datasheets and schematics: https://hands.com/~lkcl/eoma/microdesktop/
I’m looking at the SY6280, but I’m not sure what I’m looking at. I see 5V at the OUT pin going to the USB OTG, and I see no voltage an the IN line to the 5V rail. Enable is pulled high, and both resistors are good at 10k and 6.8k respectively. I have no idea how to check C9 or C8, but I assume those are good.
In my limited understanding, this does seem to indicate that the chip is faulty, right? I’ll try to get a replacement and see if swapping it out changes anything. I’ll also try to get a replacement for the RT8288 just for kicks.
-A