Is there anyone here old enough to remember working on the Sony SL-2700 Betamax? I refurbish Beta's for resale and this one has a tough problem. The VCR works fine except for hifi audio - put in a hifi tape, and the hifi indicator lights but the sound is mute, both on the output and the VU LED's. The linear sound works fine if switched to that.
Tried swapping all boards related to audio, but got the same result, perhaps one of my substitute boards had the same problem.
Any ideas?