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I'm looking for an early JC120 schematic. I have looked around online and I already thought I had all the schematics - but not this little devil.
s/n 471557
It has a separate board for the delay/chorus, and two further more or less identical boards, one for each channel. So not the usual large single board for Channel 2 plus effects.
The channel boards have mostly discrete transistors, only one IC each, a little 6-leg round case job. The discrete-transistor schem that's readily available has two FETs as the first stage, whereas this has a 2SC1681 then a 2SA493 (though there are 2SK30A fets further in).
The amp is in a dreadful state but I managed to get Channel 1 up and running, and the output stages are fine. Ch2 goes silent at the first stage because the bias is off, shotgunned a few transistors but there's something a bit further in gone wrong and it is hard to trace without the schem. I would be deeply grateful...
s/n 471557
It has a separate board for the delay/chorus, and two further more or less identical boards, one for each channel. So not the usual large single board for Channel 2 plus effects.
The channel boards have mostly discrete transistors, only one IC each, a little 6-leg round case job. The discrete-transistor schem that's readily available has two FETs as the first stage, whereas this has a 2SC1681 then a 2SA493 (though there are 2SK30A fets further in).
The amp is in a dreadful state but I managed to get Channel 1 up and running, and the output stages are fine. Ch2 goes silent at the first stage because the bias is off, shotgunned a few transistors but there's something a bit further in gone wrong and it is hard to trace without the schem. I would be deeply grateful...
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