I’m having a lot of fun with reverse engineering lately, so when I was looking over the service manual for my guitar amp, a Yamaha THR10c, and saw references to a UART header in the schematic, I got excited. I wondered if anything cool was hiding in there. Next to it was a JTAG header. I knew next to nothing about JTAG, but had heard the name before associated with hardware hacking, so maybe that would be useful as well.