cs-50

[James Dunn]

I recently purchased a Yamaha CS-50 for £40 (uk sterling). A bargain?
The only problem with it is that a high pitched noise starts after about
15 minutes of switching on. It is independent of the volume controls,
and sounds the same as when pressing the highest key with the sine wave
an octave up. I assume somehow this setting is shorting to the output.
Does anyone have any ideas before I take a look inside? It makes some
great sounds but it's getting really annoying.

Thanks,

James.