So I got the amp to work. I re-soldered the transistors back into place and turned on the amp without the speakers. TR4 did not get hot. Out of curiosity I hooked up the speakers and the amp was working fine. It sounded clean and loud. I don't know what fixed it, maybe a bad solder joint was fixed, but it works.

From the testing I did on the transistors, both of them seem to be working fine. Connections only from B to E and B to C on both of them. The 0.22 ohm emitter resistor is reading 0.6 ohms off circuit. Any other ideas? Oh yeah, I do have the amp always disconnected ever since it started distorting. The rotary amp is able to function independently.

Hi everybody. I recently bought a vintage Yamaha RA-200 from a  guy, he said its about early to mid 70's. This amp actually has 3 amplifiers. 1 for rotating speakers, and two for the top and bottom half of the 4x12s. Now the problem is that in one of the amps for the 4x12, one transistor (2SC783) started getting really hot and the sound started distorting. Now I have no idea what the problem is, and I want to get it fixed. I checked the resistors going to the base, and they are good, so I don't know what else could be the problem. Thanks for any help!

The transistor is labeled TR4 on the schematic.