Hi Guys
I am no tube amp wizard, although having ordered the PM670 PCBs recently I had better get learning Anyway I digress...... I am asking for some help debugging my Marshall 6100 amp which has developed a problem ......
The puzzle: I get a steading buzzing sound when the amp is switched on, with a guitar plugged in but not playing. The amp has a "standby" mode which seems to disable the ouput stage. The buzzing occurs even when in standby mode. My initial thought was that it was a preamp issue, and that I need to replace the preamp tubes. But now I am not so sure. Schematics:
Preamp
Power Amp
PSU
Any ideas?
The power amp tubes are a few years old, but frankly I only use the amp a few times a year. I dont know if the preamp tubes have ever been changed.
thanks
Steve
I am no tube amp wizard, although having ordered the PM670 PCBs recently I had better get learning Anyway I digress...... I am asking for some help debugging my Marshall 6100 amp which has developed a problem ......
The puzzle: I get a steading buzzing sound when the amp is switched on, with a guitar plugged in but not playing. The amp has a "standby" mode which seems to disable the ouput stage. The buzzing occurs even when in standby mode. My initial thought was that it was a preamp issue, and that I need to replace the preamp tubes. But now I am not so sure. Schematics:
Preamp
Power Amp
PSU
Any ideas?
The power amp tubes are a few years old, but frankly I only use the amp a few times a year. I dont know if the preamp tubes have ever been changed.
thanks
Steve