Casio SK-1

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Casio SK-1
Example alt text
ManufacturerCasio
Release1985
Owners ManualYes
Service ManualYes
Clones & VariantsConcertmate 500
Technical specifications
Polyphony4 Note Polyphony
SynthesisSampling, Additive
ADSR13 Preset Envelopes
Sound ChipMSM6283-01GS
Notable FeaturesSampler, one key play, line in for external mic
Input/output
Line Out1/4”
MIDI / CVNo / No
Keys32, Mini Sized

Overview[edit]

The Casio SK-1 is a small sampling keyboard released in 1985. It was the first in Casio’s line of portable sampling keyboards, followed by the SK-2, SK-5, SK-8, SK-10, SK-60, SK-100, SK-200, and SK-2100.

It has been considered a keyboard of choice by circuit benders as far back as 2005, when it was prominently featured in Reed Ghazala’s seminal book, Circuit-Bending : Build Your Own Alien Instruments. It’s lack of rarity has also served its popularity among circuit benders; Casio sold over 1 million units during its original run. However in recent years, increasing age and a cult following among lofi and retro enthusiasts has driven prices to near $100 for a used unit.


Documentation[edit]

Service Manual[edit]

A full service manual for the SK-1 exists (though in the form of Radioshack’s clone version, the Concertmate 500) complete with full circuit & block diagrams, parts list, chip pinouts, & more.

SK-1 service manual (click here to view full PDF)

IC Info[edit]

Pinout for the SK-1’s main IC, MSM6283-01GS

The M6283 has several variants. Slightly altered versions are used in Casio’s other sampling keyboards, like the SK-2, SK-5, SK-8, and SK-10. The last 4 characters are unique to each sampling model, with “01GS” being the SK-1 specific model.

The Casio SK1 has two XRAM NEC uPD4186 8 bit RAM chips that samples are recorded to and read from. Unlike other Casio SK series keyboards which can store 4 samples and retains them while there are batteries in the keyboard, the SK1 can only store 1 sample at a time and there is no sample memory. However, it is possible to modify the SK1 by removing the two XRAM chips and replacing them with two SRAM ICs, two controller ICs and a battery to increase the sample capacity to 64 samples that can be stored and write protected.

Community Documentation[edit]

External links[edit]

Further Information[edit]

  • Information/Pictures/Manuals on various Casio sampling keyboards at casiosk1.com

Circuit Bending[edit]

  • Archive of Casper Electronic’s detailed SK-1 bending guide.
  • Greightbit’s Instructables SK-1 bending tutorial. Schematics on LTC1799 re-clocking, patch bay, and LED lighting.
  • Gieskes’ unconventional SK-1 mod. Includes schematics for a CV trigger input & RCA video out.