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Yamaha Cp-30 Buzzing

Posted: Mon Sep 14, 2020 1:36 am
by LFO#2
I recently purchased a yamaha cp-30 for a steal, knowing that it probably had some problems. When I got it home and turned it on there was a loud buzzing noise, like one of the keys was constantly being pushed down at maximum velocity/ one of the oscillators is always on. The noise is only on instrument I, and thus anything I do to modify the instrument I sound (Tremolo, volume, changing instrument type.) effects the buzz likewise. If you play the keyboard, the regular instrument I sounds can be heard, but are washed out by the loud buzz. I've already poured over & cleaned all the contacts, as well as looked for any obvious signs of damage (broken components, corrosion, damaged pcb, etc) and everything looks fine, I have little idea of whats going wrong, or If its even something I can test/fix myself, But if anyone has any theories of what the source of the problem might be, help would be greatly appreciated.

to recap, the problem is:

-Loud buzzing sound coming from Instrument I only, though not the only sound that can come from instrument I

-not a sticky key

-not any noticeable damage

Thank you for any help you are able to give.

Re: Yamaha Cp-30 Buzzing

Posted: Tue Sep 15, 2020 7:45 pm
by madtheory
It's probably a component failure in that section, most likely a capacitor and/ or an IC (they're CMOS so will be failing by now) but the question is too basic, and I don't know the circuit, so I'll give you a general answer.

Yamaha provide all of their old service manuals and schematics for free. They are always very clear and easy to follow if you know electronics. You'll need to figure out the signal path, you'll need a scope, some probes connected to a powered speaker, a multimeter a soldering iron and associated tools.

But at least it is not a major fault, it's isolated to one instrument so that's a plus.

Re: Yamaha Cp-30 Buzzing

Posted: Wed Sep 16, 2020 2:41 am
by LFO#2
Thanks for the help!