A thermal printer I had connected to serial TXD and GND stopped working all of a sudden, so after a few hours of pulling my hair out I spotted this on the back of the PCB (rev1 board):
I'm not too knowledgeable with the electrical aspect of things, but I spotted this on page 3 of the schematics document:
So if I understand this correctly this is simply a resistor going to an Ethernet LED and it just means no more light shows, but could this have any other effects? Or perhaps something else blew and I can't see it..
It is worth noting the printer is fine, I swapped this Raspberry Pi out with another one I have, used the same connections, same SD card ...etc and it worked as expected. Also, the Raspberry Pis both sit comfortably inside cases so this couldn't have been physically damaged by accident.
This damaged one still boots, runs XBMC, plays media.
Maybe the resistor and the serial connection issue aren't related, I have no clue. Any thoughts?