I seem to fried something on my RPi 1 Model B by connecting a 12V source instead of a 5V source to the micro-USB port. When I now connect it to a power supply, the PWR LED turns on and nothing else happens.
This is what I was able to measure:
- TP1 to TP2 voltage is a healthy 4.9V on a short USB cable from a smooth (battery) source
- this would suggest that the D17 diode didn't burn up, at least not in a way that would leave it short-circuted (http://tinyurl.com/jkf85uq)
- this TP1-TP2 voltage is puzzling because a sole red light is supposed to mean inappropriate voltage or an unreadable SD card (http://tinyurl.com/mkgztq3), but the card is readable on my laptop, and the voltage is fine
- the F3 polyfuse seems to be fine (measured voltage drop: 0V11), which is bad news, because it suggests something else burnt up before it could activate itself (https://www.safaribooksonline.com/libra ... /ch01.html)
- voltages on C11, C15 and C9 should theoretically be 3V3, 2V5 and 1V8 and I measure 3V28, 2V47 and 1V78, so I think there's nothing obviously wrong there
Yes, it's a cheap, small device, but still, I'd like to see if it's possible to determine what failed and if it can in principle be repaired e.g. by replacing one of the simpler (2-3 connectors) components. Any ideas or suggestions?