02-05-2023, 11:41 AM
I have a '68 GV22 that I've been restoring over the past year. It was basically a barn find and in pretty bad shape. I've replaced all the electrolytic capacitors, tubes, output transformer, rectifier diodes and EVERY solder joint has been re-flown. The amp now works but I have a some noise issues. 1 is a constant hum. It sounds like it's 60hz. It does increase when the volume is raised but is not louder than the instrument. I've ruled out the hum control pot and caps. 2 is a popping noise when it's taken off standby mode. 3 is a series of popping noises that taper off when it is put back into standby mode. It sounds a bit like a helicopter. I believe that 3 may be related to the echo/trem board. I'm at wits end with this amp and any suggestions would be greatly appreciated. Oh, it does sound great when played. Volume seems normal but the hum is always in the background.