If your chorus works but is noisy (clock whine), the schematic shows the low-pass filters (op-amps IC5 and IC6) that are supposed to remove the high-frequency clock noise. If capacitors C71 or C72 drift out of spec, the whine returns.
To find the right diagram, you must first identify your unit's serial number or specific model variant: Vintage "79-3" Edition jc-120 schematic
But schematics are not passive. They are stories told in the language of voltage. If your chorus works but is noisy (clock
There are several major revisions of the JC-120 circuit. Identifying your serial number is critical for accurate repair. 1975–1979 (Early "Toggle" Era) Metal jacks. They are stories told in the language of voltage
The JC-120 hummed. Then the chorus engaged. Two signals, slightly out of phase. One voice—hers—arriving a fraction of a second after the other. But her father’s modification, the red-ink change to the clock generator, had stretched that delay. Not to a slapback echo. To something else. The second voice arrived 2.7 seconds later. Then a third. Then a fourth.
