Korg PolySix -1981    Weight = 24.5 Lbs. Number mfg.= 30,000 MRP=$1095

User Manual: VSE
Reset Proceedures: N/A
Operating System code: 8048 and 8049
MIDI or other control protocol: N/A
Software related Links: N/A
Patches or knob settings: factory 'a' or factory 'b'
Circuit Overview: below
Scematics/Service Manual: Old Crow's or Florian's pdf
Common Service Issues/Tips: below
Parts Sources: Keys knobs semiconductors NEW Prog PC (raw unpopulated) Board KLM-367 or synthronics.de KLM-367, 368, 370 and whatever you find :-) misc
Uncommon chips/modules used: M5230L Voltage Regulator, SSM2044 VCF, SSM2056 EG, MN3004 BBD's, LM13600 dual OTA's, P8048 and P8049 ROM masked processors, MC1408 DAC, TC5514AP 1Kx4 SRAM
Modifications:PolyM Midi or PIC MIDI diy project or Martin Wise' CPU board/MIDI
General Info Links: Vintage Synth Explorer

Circuit Overview:
     A fairly basic analog synth with memory and bbd chorus/ensemble/phaser. Knobs track from current memory location rather than knob location which I always prefer in performance. One of the few polysynths in the affordable range that has full analog signal path and analog EG's. Arpeggiator is pretty nice also. See my Youtube Video explaining the basic overview of how a storage analog synthesizer works. Also see my Polysix Video showing some more detailed internal information.

Service Tips:
     Have seen problems with Chorus boards and also failure in LM13600 dual ota chips. My own unit however had the peculiar symptom of having noise instead of oscillators it seemed. Since..there is no noise source by design this was a little puzzling. Turns out though that the 4066 chips which turn on/off the signal flow from the various oscillator sources (ie. pulse, saw) were receiving a bizarre signal from the 4042 latches. Another unit had lights on all the time like 2,3 and b,c. These problems are typical of what happens when lines get dissolved by the battery acid. They often APPEAR to still have copper in them..but can be totally non-conductive oxides in place. You simply have to Cut out the 74LS08 near the battery and before replacing it totally check every connection and trace in that vicinity.See helpful tips on Old Crow's site. Or see my advice in poly-61 section for service tips if that doesn't work.
     Now another thing which might fail is the SRAM chip. I've only seen this once but others say it's common. The problem is, there aren't a lot of really good options because this is a very low drain 1Kx4 SRAM chip. The HM6514 is noted to be equivelent and easily available from Jameco but the problem is, it uses way more power when it's turned off. Hence it drains the battery and you'll leave it in the closet and pull it out in a few years and your patches are gone. The NICE thing about Polysix is you can save a patch dump to a .wav file on your computer or .mp3 and it's a very small file, and they reload very reliably (always do verify of course) but KUDOS to KORG on the design of this interface. It's the best I've seen. Simple to use. Anyway the 6514 draws like 40uA in sleep mode..while the TC5514AP draws 20uA max. However the APL version used in the Polysix uses only .2uA or something! So it's a huge difference and if possible get the original chip in there. They're getting scarce. Chipforbrains is selling them on ebay for 18.99 as I speak (11/3/08). He has 8 left after I got a couple.
     And of course the keyboards on these machines are notorious for developing problems with intermittent contacts or dead notes. The process I've used with scrubbing them tightly with acetone worked on many but I finally hit a unit that ate hours of my time and wouldn't cooperate. It kept going back to intermittent. I believe I have a solution. I have used the restoration paint from both caig and loctite I think it is (Oaktree sells it). I've had hit and miss results with it. Sometimes I have to recoat things and I dont' have a long term test on it BUT...I've tought of a way to totally restore these contacts to good as new I believe. I'll have a release about this at some point.

I believe you'll draw mostly blank looks from Korg on these units. I have some parts 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. I have SSM2044's for instance and 2056's. Occasionally parts are on ebay also.Contact me.