Electronic Repair

Early Yamaha CS-80 monster. I heard this was the first one imported to the US! When it arrived, one voice was out. But which one? There's no easy way to tell which voice card is being gated. There are 16 voice cards total. Both of Voice One's tone cards were not making sound. The problem was with the TWS board. One of the opamps was outputting the minus supply voltage bringing both voice cards' VCAs down with it. I went ahead and replaced all the opamps, the electrolytics, and the tantalums on that board.

Other fixes... I changed out the power supply electrolytic capacitors, power transistors, and replaced the corroded lead wires on the power supply, cleaned all the controls, calibrated tuning, replaced the AC cable, and changed all the preset bulbs.