Roland jc 120 serial dating
These speakers also seem to lack the metal dust cap This is actually the model of which's schematics are most commonly referenced when people request for a JC-120 schematic.An important point is that the schematic (often passed on with nickname "1984") doesn't match ANY of the JC-120 combo designs by a long shot.Rear panel arrangement from left to right: Fuse holder, two speaker out jacks (left), two speaker out jacks (right), Sub In jack, three footswitch jacks for chorus, reverb and distortion, effect line out jack, normal/mixed line out jack. Personally I've not enjoyed the early ones I've had (three) as they were noisy and the much vaunted analog chorus wasn't sounding that great. Ampli souffrant à priori d'un bruit de fond élevé, plutôt surprenant pour un transistor, a vérifier lors d'un achat...The 4th and 5th editions do have a different chorus sound but they are a bit quieter and sound superb. Citation de https:// I recently bought a used Roland jazz chorus 77 and have a question about the infamous noise these things make.JC-120 serial: 380100 - 415099 input stage BJTs FETs 420600 - 471649 input stage similar 481650 - 502499 input stage IC TA7122 512500 - 779499 input stage similar 789500 - 248099 input stage FETs (950100 - 283149 USA) same 258100 - up input stage FETs BJTs (293150 - up USA) same Ici, un descriptif des différents modèles avec les changements Citation de https:// - Line out tap at speaker output JC-120 S/N 420600 – 471649 JC-160 S/N 440100 – 470549 - Pretty much similar to revision described above - Separate LF oscillators for vibrato and tremolo. JC-120 S/N 481650 – 502499 JC-160 S/N 480550 – 500849 - Gain stages are TA-7122AP, low noise integrated preamp ICs - Distortion circuit is a switched on cascade of two BJT FET based gain stages - FET-differential pre-limiter preventing power amp hard clipping - Current feedback power amplifier (meaning, the output frequency response is not linear but instead varies in interaction to speaker's impedance, similarly to many tube amps) - Discrete BBD oscillator driver - Separate LF oscillators for vibrato and tremolo. Chorus mode has fixed settings for vibrato speed & depth - Line out tap at speaker output Note : Cette version aurait un chorus plus proche du CE-2 que du CE-1, mais ça reste à vérifier.topic=2243.0 : 3rd Edition (1979) - applicable to JC-120 S/N 380100 - 415099 - Gain stages are discrete, combinations of BJTs and FETs - Distortion circuit is an overdriven FET BJT stage permanently in circuit - Features a FET-differential -based "pre-limiter" preventing power amp hard clipping - Discrete BBD oscillator driver - Separate LF oscillators for vibrato and tremolo. JC-120H - the head unit (1984) – applicable to 100/117V 70126811 220/240V 70126814 - Gain stages are Op Amp –based - “Single channel” - Distortion circuit is a switched on combination of two parallel shunting diode clippers switched in gain control in the preceding stage - Revised reverb circuit with BJT drivers and current feedback - “Hi-Treble” potentiometer control - “Sub In”, external mono input - “Normal/Mixed” and “Effect” line outs preceding power amp - Four speaker out jacks (this is a head) - BBD and LFO setup similar to 5th edition of the circuit JC-120 UT / JT (2nd Edition - these are the newest JC-120 amps) - Gain stages are discrete, FETs or combinations of FETs and BJTs.The difference to certain combos that had line out jacks is the take off point.
Pour ceux qui chercherait un HP de remplacement https://taweber.powweb.com/weber/cali12FX loop circuitry also uses Op Amps - Distortion circuit is a switched in FET gain stage with diode clippers in feedback loop, very similar to circuit of "5th ed".but some component values are different - Modern FX loop with loop level selector and all other goodies - BBD and LFO setup similar to 5th edition of the circuit - Revised reverb circuit, similar to JC-120H model - Output –tapped “Line out” feature omitted Another important difference are the speakers.These have a distinctive metal dustcap and either a black&blue or black&white label.R&P speakers were developed in collaboration with Pioneer in the late 1970's, they basically appear in circa 1979 amp revisions.These drivers featured some fancy innovation but I'm not entirely sure what it was; basically they seemed to have a wider and Hi Fi'er response than generic Roland speakers of the time and the new technology was marketed keenly.The Roland amplifiers featuring these speakers were marketed as a unique top notch line, either indicated by "A" or "R&P" in the model number.Or, selon le post de Musicalist, les séries ante-79 auraient pour particularités apparentes - coins chromés - entourages de boutons gris sauf pour les vib/chorus, entourés de vert - petit logo R Roland - HP Musical Speakers - 6 entrées/sorties jacks à l'arrière (3 footswitches 1 préamp out 2 HP ext) sans loop - pas de switch " bright " en façade - etc. Donc, grâce à toutes ces infos, mon JC daterait de février 1977 (ou de juin 1985 d'après le tableau si je tiens compte de la remise à zéro des serial de chez Roland). Ma contribution : Earlier models JC120 is easily identified by the look of the rear panel.Je doute qu'il date de 1985 car il a toutes les caractéristiques des modèles pré 1979. JC120 started producing 1975 and had a footswitch connection for reverb at rear side then at January 1976 chorus/vibrato footswitch was added.In October 1976 JC120 gets new connection for distortion and 1978 new jack for ext speaker. - Line out tap at speaker output - LDR-based muter for the chorus/tremolo JC-120 S/N 512500 – 779499 JC-160 S/N 510850 – 282918 - Pretty much similar to one described above 4th Edition (1979) – applicable to JC-120 S/N 789500 – 248099 or 950100 – 283149 (USA versions) JC-120A and R&P S/N 810600 - 001099 JC-160 S/N 782921 - 244509 - Gain stages are discrete, FET -based - Pre-limiter circuit omitted, will be omitted from following versions - Distortion circuit is an overdriven FET stage switched into the circuit - “Main In” external inputs - Current feedback used in the power amplifier - BBD now with driver, pre driver made out of digital logic and discrete circuits - Separate LF oscillators for vibrato and tremolo.1979 there is two main in jacks and jacks for footswitches and ext speakers are changing place until 1984 when JC120 gets modern design of rear plate. Also includes a trimmer for chorus adjust in rear panel. Normal vibrato controls in front panel, chorus adjust trimmer in rear panel. 1982) – applicable to JC-120 S/N 258100 and up or 293150 and up (USA versions) JC-160 S/N 254510 and up - Gain stages are discrete, FETs or combinations of FETs and BJTs - Current feedback from PA is omitted and no longer featured in following versions - Includes a bright switch - Distortion circuit is a switched in FET gain stage with diode clippers in feedback loop - “Main In” external inputs - BBD BBD driver setup - LF oscillators for chorus and tremolo now combined to a single circuit.