Haven't been able to find one from my usual sources.
Have a MC7200 in the shop now whose left channel only works when the rear panel switch is in Bridge mode. In Stereo mode, it acts as if coupled by a few hundred pF (output increases with frequency and is in the microwatt range).
I've been able to determine that the bridge board and switches are functioning.
Apparently the left channel gets its signal from a different path when in stereo mode than Bridge mode. But it's not a good physical access area and the board is too dense to make a schematic in a reasonable amount of time.
If anyone's got a copy of the SM, please PM me. Thanks.
Have a MC7200 in the shop now whose left channel only works when the rear panel switch is in Bridge mode. In Stereo mode, it acts as if coupled by a few hundred pF (output increases with frequency and is in the microwatt range).
I've been able to determine that the bridge board and switches are functioning.
Apparently the left channel gets its signal from a different path when in stereo mode than Bridge mode. But it's not a good physical access area and the board is too dense to make a schematic in a reasonable amount of time.
If anyone's got a copy of the SM, please PM me. Thanks.
Solved problem. A shorted J-FET at the input. The amplifier has two different inputs on the PCB--one fed by the bridge circuit and one that is dedicated to the left input jack.
This amplifier shows evidence of an electrical surge--a fuse was blown initially when it arrived DOA. After replacing the fuse, the amplifier came to life, but for the left channel in stereo mode. This shorted FET suggests some sort of medium intensity EMP event took place involving this amplifier.
I have replaced the FET and all is well now.
This amplifier shows evidence of an electrical surge--a fuse was blown initially when it arrived DOA. After replacing the fuse, the amplifier came to life, but for the left channel in stereo mode. This shorted FET suggests some sort of medium intensity EMP event took place involving this amplifier.
I have replaced the FET and all is well now.
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