Korg 770 -1976    Weight = Lbs. Number mfg.= ? MRP=$1099

User Manual: fdiskc archive or Korganalogue.net
Reset Proceedures: N/A
Operating System code: N/A
MIDI or other control protocol: N/A
Software related Links: N/A
Patches or knob settings: N/A
Circuit Overview: below
Scematics/Service Manual: fdiskc archive
Common Service Issues/Tips: below
Parts Sources: Keys knobs semiconductors misc
Uncommon chips/modules used: TH7140P, TS201012 VCF module (unpotted)(Thanks Colin Fraser for this great page/research!)
General Info Links: Vintage Synth Explorer

Circuit Overview:
     A simple 2 vco monophonic synth with ring mods. Apparently the filter design is an unpotted version of those used in the earlier 700(S) and 800DV units according to Colin Fraser. He notes "Only difference is that the 770 uses diode arrays instead of discrete devices and doesn't have the cutoff range shifted by the octave selector switch as on the 700(S)."

Service Tips:
     There are lots of discrete transistors and 2902 op amps in these. I've never worked on but at this age look for failing electrolytic capacitors. AN esr meter is always nice.

I believe you'll draw mostly blank looks from Korg on these units. I have some parts that are the same so feel free to ask what the current stock is on a given thing. Some of the less common parts are getting quite hard to find though. THings pop up on ebay now and then.. Contact