Jc-120 Schematic

When the chorus is engaged, the schematic shows that the effect circuitry routes the dry signal to one power amp (and subsequently one set of speakers) and the wet, chorused signal

The input stage of the JC-120 is where the characteristic "chime" is born. Looking at the schematic for the input section (often centered around the input jack and the first few transistors or op-amps depending on the revision), we see a design focused on fidelity.

Some pics that display cosmetic differences of JC-120's of different pedigrees: From top to bottom. - Very old version of the amp: Solid State Guitar Amp Forum Support - JC-120 - Owner's Manuals - Roland jc-120 schematic

The is a document of genius. It represents a time when designers like Mr. Kakehashi and Mr. Katoh engineered analog circuits that have never truly been replicated by digital modellers.

This generation introduced the push-button chorus selection and standardized many internal components. This era’s schematic is the most commonly referenced for repairs. When the chorus is engaged, the schematic shows

This schematic is frequently used as a reference but differs from combo models. It replaces the "Bright" switch with a "HI-TREBLE" pot and uses op-amp-based gain stages.

The primary preamp and power amp circuit layouts. - Very old version of the amp: Solid

Always verify that a found schematic matches your specific amp revision based on the identification guide above before you begin any work.

Do not trust blurry JPEGs from random forums. A pixelated schematic will lead to misreading a 100k resistor as a 10k, blowing your power transistors.