Musical Fidelity B1
Hi,
I've recently been given one of these hi-fi amps in a state of deadness.
I think I've fixed it (failed output transistors) but I'm struggling a bit with the output stage bias adjustment. It's a class AB amplifier.
Does anyone happen to know the procedure for adjusting the bias?
I haven't got very far with inspired guesswork and twiddling, apart from being able to obtain 0V DC offset on the speaker terminals, not have it threaten to go into thermal runaway... and produce audible and visible distortion on a 1kHz sine wave when the volume is advanced to "reasonable"...
Both channels are behaving similarly.
The circuit (attached) is interesting, to say the least.
Cheers, Kat
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