Lowell,
I would check the other leads of D12 and D1 - there should be +-43V. If this is true, still the problem can be either in the servo or the input stage. I would check both but I suspect rather the input stage. Have you noticed that several resistors in the amp are marked as FUSE? Especially resistors in emiters of Q10, Q14, Q8 and Q11. If for example R33 (emiter of Q14) is broken, you may have symptoms like you've just measured. You also have voltages on these resistors specified on the schematic so I suggest to check them.
Marek
I would check the other leads of D12 and D1 - there should be +-43V. If this is true, still the problem can be either in the servo or the input stage. I would check both but I suspect rather the input stage. Have you noticed that several resistors in the amp are marked as FUSE? Especially resistors in emiters of Q10, Q14, Q8 and Q11. If for example R33 (emiter of Q14) is broken, you may have symptoms like you've just measured. You also have voltages on these resistors specified on the schematic so I suggest to check them.
Marek
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