Each channel features a 3-band EQ and a dedicated Bright Switch . 📈 Revision History
Current production units are closer to the 1980s designs but updated for modern electrical safety standards. jc-120 schematic
Unlike the combos, this schematic is heavily op-amp based rather than discrete transistor-based. It also replaced the Bright switch with a "Hi-Treble" potentiometer. Each channel features a 3-band EQ and a
While the JC-120 schematic is a fantastic learning tool, The power supply caps can hold a lethal charge (over ±60V DC) long after the amp is unplugged. Unlike tube amps, solid-state circuits can be destroyed by accidentally shorting the wrong pins during probing. It also replaced the Bright switch with a
The Roland JC-120 Jazz Chorus features a complex, evolving design with 6 to 7 circuit revisions since 1975, primarily utilizing BBD-based (MN3007/MN3002) stereo chorus. Schematics are divided into preamplifier, distortion, and dual 60W power amp sections, with variations across early, mid-80s, and modern models. For technical diagrams and service manuals, visit the Roland Support Site or Schematic Heaven . Politechnika Gdańska +3 4 sites jc-120/jc-160 service notes MIDDLE, REVERB. CABINET ASSEMBLY. 13219210. EVH-6PA361A15. 100kA. (Including Handle, Badge, Corner Protector, Rubber Feet. VIB, SP... Politechnika Gdańska The Clean Legacy of the Roland Jazz Chorus First introduced way back in 1975, the JC-120 Jazz Chorus is one of the few guitar amps that can truly be called a legend. Roland' Roland - Global Roland JC-120: The Clean Sound Revolution Apr 3, 2026 —