Hello folks
I have a silverface champ AA764 amp, schematic:
http://ampwares.com/schematics/champ_aa764.pdf
On start up there is extremely loud hum/buzz even with volume on 0 and nothing plugged in. Volume control does effect the sound when turned. Pulled preamp tube and hum remains. Hum goes away when power tube is removed.
-Tried different speaker
-Chopticking all connections does not effect anything.
-Checked all ground connections, no problems.
-Cleaned/tensioned pins, jacks, pots
-Swapped all tubes (rectifier, power, and preamp) and hum/buzz remains with each new tube.
-Checked all pin voltages on tubes per schematic and all are in spec (used dummy load to avoid noise).
The amp is all original with no mods. It has the 20/20/20 can cap and original coupling caps. Would a bad filter can produce extremely loud buzz/hum like this? I have no problem doing a cap job but want to rule out other possibilities.
Thanks for the help!
I have a silverface champ AA764 amp, schematic:
http://ampwares.com/schematics/champ_aa764.pdf
On start up there is extremely loud hum/buzz even with volume on 0 and nothing plugged in. Volume control does effect the sound when turned. Pulled preamp tube and hum remains. Hum goes away when power tube is removed.
-Tried different speaker
-Chopticking all connections does not effect anything.
-Checked all ground connections, no problems.
-Cleaned/tensioned pins, jacks, pots
-Swapped all tubes (rectifier, power, and preamp) and hum/buzz remains with each new tube.
-Checked all pin voltages on tubes per schematic and all are in spec (used dummy load to avoid noise).
The amp is all original with no mods. It has the 20/20/20 can cap and original coupling caps. Would a bad filter can produce extremely loud buzz/hum like this? I have no problem doing a cap job but want to rule out other possibilities.
Thanks for the help!
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