Expert: Cleggsan - 2/10/2011

Question
I recently picked up a Fisher CA-276 amp at a garage sale. It seems to work ok but the volume control is stuck to wide open causing it to blast through my speakers. The knob turns but does not affect the volume. Any ideas on what may be the cause and is it worth it to fix? I'm sorry but the only info I have on it is the model number. Thank you for your time and consideration.

Answer
I think this unit has carbon resistor based volume controls. I could not find a manual on this model but I did find one very similar (CA-272) which does use conventional wiper controls.

The problem, therefore, is likely that the wiper element has either worn out the carbon deposit inside the potentiometer or it has lifted off the carbon entirely.  If the shaft of the volume pot were pushed in hard it could force both wipers of the right and left gangs to open up - not an uncommon occurrence.  It will require replacing the rotating potentiometer.  

You might want to bang on it or tap on the pots to see if that will indicate the above idea.

You may be able to find a dual audio taper pot that could be wired into the unit.  

The value of the audio volume control is 250k according to the similar model.

PS: Final note:: your model may have sliders rather than rotating volume control, but the principle remains the same.

PPS: I wrote this in a hurry, if it is not clear, be sure to send me a followup question.