Yamaha DX-21 -1985    Weight = Lbs. Number mfg.= ? MRP=$795/?/$599

User Manual: Yamaha
Reset Proceedures: N/A
Operating System code:
MIDI or other control protocol:
Software related Links: N/A
Patches or knob settings: Cool patch database!
Circuit Overview: below
Scematics/Service Manual:
Common Service Issues/Tips: below
Parts Sources: Keys knobs semiconductors misc
Uncommon chips/modules used: Many
General Info Links: Vintage Synth Explorer

Circuit Overview:
     A digital synthesizer which utilizes special processing chips designed to support Yamaha's FM synthesis architecture. This one having 4 operators and 8 algorithms. This is the cheap DX to have for the dynamic possibilities! Cool effects attainable by using the layer pan slider and it has a more succinct envelope control than the DX7 giving better attacks I've been told and seem to hear as well on mine. Definitely a lot of fun for the mon. :-) The typical VLSI chips that seldom see problems in this series so not much point going into actual circuitry descriptions here.

Service Tips:
     I've found most of these units to be fairly rock solid circuitry wise. Abused units sometimes have solder problems. I've fixed the few I've had in by just going over suspected areas of the circuit boards soldering questionable joints! If anyone needs serious work on these I do have diagrams but...I seriously can't imagine anyone needing..serious work on these since they come up cheap.

While Yamaha normally does not keep parts around more than 5 years or so, I try to stock what I can. Out of dx knobs
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