Yamaha CS-50

4-voice little brother of the mighty CS-80, for sale serviced and in excellent working order. Please note: Shipping...

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4-voice little brother of the mighty CS-80, for sale serviced and in excellent working order.

Please note: Shipping fees are an estimate, but it will not be cheap – please ignore shipping price quoted and get in touch for an accurate figure.

Recently worked on for us by a top synth tech. Full service report below.

This Yamaha CS-50 is for sale in very good condition overall. It has minor signs of age and use across the unit. Important to note that all of the slider caps (the top row of controls) have been replaced with new ones all in black; the volume knob is also a replacement, and finally three of the paddle controls that were originally grey are now white versions (they are the Ring Mod Depth & Modulation, and also the Touch Response Level). The case is somewhat scruffy with plenty of scrapes and some of tolex missing in places; it is physically sound, however. See photos for more information on cosmetic condition.

Complete with the detachable chrome legs.

Switchable voltage.

Engineer’s report:

  • Unit droning from power on. Trigger buffer IC7 on KAS board with stuck outputs. Replace device
    and keyboard now able to trigger M cards. Voice M4 mute when triggered. Chasing the signal
    revealed that the final stage VCA was defective with a large DC offset at the output. Replace
    iG00151 device. All four voices now sounding however two of them are stuck on the same note. S/
    H logic, IC1/2, defective and replaced.
  • PWM effect not available on pulse wave. LFO chip with dead SIO pin in SUB board. Replaced
    iG00150 device.
  • Replace all electrolytic capacitors in PSU. Replace damaged Bakelite mains plug with modern
    BS1363A type fitted with 3A fuse.
  • Replace leaky electrolytic capacitors on all M cards. Remake the thermal bonding on all 4 x VCO III
    devices. Replace temperature compensation diode on card M3.
  • Full functional test and tune. Filters well matched but VCA levels trimmed so that the amplitude of
    all M cards the same. Clean jacks, switches and pots.
  • Clean unit inside and out. Replace slider caps with generic types due to missing originals.


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