Mid 70s Silverface Fender Champ...new power transformer, new cap can, new cathode bypass caps. Resistors all within spec...voltages all present and correct. Low volume....at 10 it's as loud as another blackface champ on 4...through the same speaker. Lacking in high end also. I subbed in a new output transformer, no change. New tubes make no difference either. I retouched the solder on the pots, tube sockets and circuit board. Chassis grounds are solid, pots and jacks are tight. I'm stumped...please direct me to a solution. Thanks for your help!
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Fender Champ Low Volume
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Agree with Helmholtz- trace signal. I'll add: What replacement power transformer is installed and what exactly is your B+ voltage? Many of the Champs were running much higher plate voltage than what the schematic you posted says. Higher B+ would give you more output. If you still have access to both amps, I'd compare plate voltages from one amp to the other. Also, are both volume pots the same taper and/or have either been replaced? Check that the amp gives you expected power output regardless of volume knob position."I took a photo of my ohm meter... It didn't help." Enzo 8/20/22
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Originally posted by acorkos View PostVoltages all present and correct
Was your amp modified to blackface specs?
What is the actual screen voltage measured at 6V6 pin 4?
Do controls work as they should?- Own Opinions Only -
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Originally posted by acorkos View Post6v6 pin 4 370V
Pin 3 360V
B+ 374V
When I scope V1 pin 1, the input signal is increased 40x
Now dime all controls and scope the 6V6 grid. If the signal is distorted lower the volume until you see a perfect sine.
Then scope the output (connected to 8R dummy load).- Own Opinions Only -
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