Jc-120 Schematic May 2026

Pro Tip: Locate the serial number on the back panel. If you see "MA" (Roland Japan), you likely have the discrete power amp. If you see "FI" (Roland Italy), you have the later European revision.

The Roland JC-120 schematic is a blueprint for transparency. While tube amp schematics are often diagrams of distortion—stages designed to overdrive the next—the JC-120 schematic is a diagram of linearity. It is an exercise in keeping the signal pure until it hits the Chorus circuit.

From the high-impedance FET input to the high-voltage discrete power amp and the bucket-brigade modulation, every line on the schematic serves the purpose of creating the coldest, cleanest, and most distinctive platform for guitarists in history. It proves that "warmth" is not exclusive to glass bottles, and that a well-designed solid-state circuit is just as musical as its thermionic counterparts. jc-120 schematic

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The JC-120 schematic is unique because it splits the signal into two paths after the effects section.

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The schematic shows the "Dry" signal bypassing the BBD and the "Wet" (delayed/modulated) signal coming out of the MN3007. These two signals are mixed back together. Because the Wet signal is slightly detuned by the LFO, combining it with the Dry signal creates phase interference—this is the "swirling" Chorus effect. Pro Tip: Locate the serial number on the back panel

On the Vibrato setting, the schematic shows that the Dry signal is removed from the mix, leaving only the pitch-modulated Wet signal.

In the output section, you will see smaller components like diodes and resistors protecting the power transistors. These prevent voltage spikes (from inductive speaker loads) from destroying the output devices. The JC-120 schematic is unique because it splits

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The secret lies in the MN3007 IC (Integrated Circuit). This is a "Bucket Brigade Device" (BBD). On the schematic, you will see this large chip near the center of the effects board.