V-M 160 vintage tube amp servicing
This is an old square dancing dual-channel tube amp from the 50's. It's got one channel for a record player and one for a microphone for the caller. It had some really bad hum problems.
Luckily it came with a schematic inside. If only consumer electronics were like that these days.
It looks pretty gnarly inside but everything, including the stacked capacity bank, seem to be functioning. I ended up replacing the power cord with a three-pronger and grounding the chassing. Most of the hum is now gone. It's a great clean amp but hard to get any distortion out of it.