Casio SK series -1987     Weight= 1? Lbs. Number mfg.= ? MRP=$150

User Manual: SK site (SK-1, SK-5, SK-8(A), SK-10, SK-60, SK-100 (200) )or Manual Manor
Reset Proceedures: N/A
Operating System code:
MIDI or other control protocol:
Software related Links: N/A
Patches or knob settings:
Circuit Overview: below
Scematics/Service Manual: CasioSK site (SM's for SK-1, SK-5, SK-8(A) )
Common Service Issues/Tips: below
Parts Sources: Keys knobs semiconductors misc
Uncommon chips/modules used: Many
Modifications:MIDI/Trigger mod
General Info Links: Vintage Synth Explorer

Circuit Overview:
     Your basic digital sampling with PCM samples. The SK-100/200 have the same drum selections as the HT-700. Pretty good stuff!

Service Tips:
     I got an SK-200 in that had massive noise issues on the rca outs. Come to find that on the HT-700 they are direct connected to ground but not on these. They apparently rely on a transistor to bring them to ground and apparently something went wrong. I just shorted it though after investigating the circuit and finding out it's pretty much identical in that section to the SK-5 which we have a service manual for online! yay!

Anyway the really annoying auto-power off feature... or whatever you want to call it...curse? Curse is a good word. Thanks morons for not putting in a DEFEAT SWITCH! LOL. All you have to do I see is cut the line to the cpu pin 64 and pull it up to positive voltage with a 10K resistor or the like. MSM6283 should be the number on that cpu or the like. Anyway once you give a positive feed there all the time (it may not even be necessary but don't force me to read the crummy diagram! Just install the 10K resistor to V plus and all will be well I'm sure. Install it on the line that continues away from the CPU but cut the line TO the cpu..hope that is clear. ie. just leave the cpu hanging in the breeze on pin 64. strip the trace and tie a 10K on that thing and put the other side of the 10K resistor to the collector of the power transistor that V plus input from power supply is tied to the emitter of, ideally.

Easy to come by on ebay. Ok now they sell for too much. Should have gotten a spare when they were 1.50 at the thrift store.