Casio CTK 731 Power supply issues

[ollyh35]

Can anybody help me? I have a Casio CTK 731 which have had for ages now and has always worked perfectly. But fairly recently the power supply stopped working. The keyboard still works when supplied by battery but not without. I bought a new pack but still without batteries it doesnt work. Plus now if I use batteries and power pack at the same time the keyboard sounds all come out weird with a sort of tremolo effect on them. This whole  problem started when I accidentally left the power supply plugged in and switched on at the mains but not plugged into the keyboard.

Short of sending it off to casio which Im guessing would costa small fortune, does anyone have any possible solutions? Either repairs that i can carry out myself or some other way of getting the blasted thing fixed.

[Gordonjcp]

Sounds like the old power supply is knackered and the new power supply isn't up to the job.  Check that the polarity is the same (IIRC Casio is negative-to-middle), the voltage is about the same (about 9V), it's DC output, and it puts out at least the same current as the old one.  More is good - better, in fact - but less current will give you all sorts of problems, including the weird sounds you describe.