Enthusiast forums like SSGuitar often host specific schematic versions, such as the "1984" op-amp based design or earlier discrete versions.
| Section | What it shows | Useful for | |---------|---------------|-------------| | | Two identical channels (Normal/Bright) using NJM4558 or MC1458 op-amps | Gain mods, tone stack analysis | | Chorus/Vibrato | BBD delay lines (MN3004 or MN3007), clock generator (MN3101), LFO | Repairing chorus "whoosh" or clock noise | | Power Amp | Discrete complementary symmetry (2SD718/2SB688 or similar) | Bias adjustment, output transistor replacement | | Power Supply | ±15V regulated (for op-amps), +25V for chorus BBD, +45V for power amp rails | Hum diagnosis, recap planning | jc-120 schematic
"Roland JC-120 service manual pdf" "JC-120 schematic full" "Roland Jazz Chorus 120 schematic diagram" clock generator (MN3101)