Jc-120 Schematic

Each channel (Normal and Effect) features its own 3-band EQ and a Bright switch , which increases articulation by boosting high frequencies at lower volumes. In early versions, these stages utilized discrete transistors, while newer revisions (like the JC-120UT/JT) incorporate a mix of FETs and OpAmps for the gain and effects loop stages. 2. The Chorus/Vibrato Circuit

| 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

Generally a mono spring reverb tank, though some schematics show it could be modified for stereo-like separation. Each channel (Normal and Effect) features its own

The schematic of a JC-120 can be intimidating due to its component density. Breaking it down into functional blocks reveals its brilliant engineering. 1. Dual-Channel Input Stage The Chorus/Vibrato Circuit | Section | What it

The amp operates with significant headroom to deliver its signature 120-watt (RMS) output (60W x 2), ensuring that the output stage does not distort easily. Serviceability and Considerations

The BBD chip acts like an analog delay line, passing the audio signal down a chain of capacitors like a bucket brigade passing water.

The heart of the JC-120’s "clean" sound lies in its robust power supply. The schematic reveals a bipolar power supply capable of delivering high voltage and current to the power amp section, ensuring 120 watts (60W + 60W stereo) of RMS power.