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Started by teemuk, July 26, 2011, 01:33:27 PM
Quote from: vin97 on January 14, 2017, 12:32:15 PMI've spotted an JC-120 that may be one of the older models but the seller doesn't have the label with the serial anymore.He says that the vibrato effect doesn't work but the chorus does.How difficult/expensive is it to repair the vibrato?
Quote from: teemuk on July 26, 2011, 02:03:18 PMSome pics that display cosmetic differences of JC-120's of different pedigrees:From top to bottom- Very old version of the amp: Notice the chrome corners and the overall green-ish colour scheme.- Somewhat newer version (approximately 1982 and onward): Notice the addition of "bright switch" feature, plastic corners and a grey-ish colour scheme. Jacks are now insulated type with plastic cover (instead of old plain metal jacks) and the potentiometers knobs are different too (they have varied slightly throughout the series' history). The Roland logo in the grille is also bigger.- Even newer one: Bright-switches are now push-button -type, the Vib/Off/Chorus -toggle has been converted to a rotary selector -type. Speakers are different and no longer have metal dustcaps. At some point of the revision history the metal "lever" -type rocker mains switch converts to modern plastic rocker switch.Samples of rear panels differences.From top to bottom:1. Very early version. Note the lack of rear cabinet panel and that the labels were silkscreened to the painted chassis. Controls from left to right: Mains/polarity switch, convenience AC outlet, Chorus/Vib F/S jack, Reverb F/S jack, Distortion F/S jack, two EXT speaker out jacks, line out jack (mono).2. Newer version. A rear panel with label stickers is added (this was probably a cheaper solution than silkscreening the chassis). The control/jack arrangement is the same except that a fuse holder replaces the mains switch and that the convenience AC outlet is removed. A briefly earlier version (ca. 1976 and not depicted) still had both fuse holder and the convenience outlet. A Chorus trimmer potentiometer is also added to the far right.3. Late 1970's version. Controls from left to right: Mains fuse holder, chorus adjustment trimmer, two EXT speaker output jacks, line output jack, chorus, reverb and distortion footswitch jacks, two mains in jacks.