210-65 2275-65 squeal
Replaced all electrolytic caps, new glass, new reverb tank, sounds fine until you get gain over "7" and then it squeals, like a self generated feedback loop. I would not think this is "normal", I must be missing something somewhere.... Suggestions? Thanks!
Member for
10 years 7 months
Member for
10 years 1 month
I would also check the…
I would also check the cathode bias voltage using the small trim pot on the main board. An out-of-spec voltage will cause a cross-over distortion that is like a crazy loud squeal. See the Service Bulletin #1 for the procedure and voltage check.
Does the amp squeal with no input signal? If so, then the trimpot needs to be adjusted to bring the voltage back to 25mV at the test point (390 ohm resistors) Above 30 mV…I have observed to voltage on the resistors to start climbing upwards for no apparent reason creating the horrendous squeal you describe.
Also, for the best use of the distortion seems to be to turn Down the Gain as you turn up the volume on the amp and guitar.
I don’t know the details of the distortion mechanism, but it is a clipping diode on the collector (?) leg of the small transistor ZTX.
You say GAIN but where is…
You say GAIN but where is the master! If it's on 10, that's freaking loud! Almost any amp will howl up there. Need a little more info than it just howls. What guitar. how close, what pickups.