To find the right diagram, you must first identify your unit's serial number or specific model variant: Vintage "79-3" Edition
A proper report on the JC-120 architecture highlights its "True Stereo" design, where the power section is split into two independent 60-watt amplifiers. jazz chorus jc-120 - Roland jc-120 schematic
She sat on the garage floor, listening to her own words decay into noise. And then, between the 127th and 128th repeat, she heard something else. To find the right diagram, you must first
R117: 1k (no, 2.2k? no—silence) C23: 47uF (replace with 100uF, bleed faster) D4: 1N4148 (remove. bridge. let it flow both ways.) R117: 1k (no, 2
These later versions (produced into the 1990s and 2000s) feature updated FX loops with stereo returns and different switching configurations for chorus and reverb. Key Circuit Sections
A "folded delay line" or "Z fold" spring reverb tank is driven by a dedicated drive/recovery circuit using 4558-type op-amps Power Supply:
She didn’t understand until she built it.