>> > I have the same problem >> > > I have a Yamaha CLP-411 Clavinova that is about five years old. It has
>> > > developed an occasional rumbling sound that comes from both speakers.
>> > > It only lasts a few seconds at a time, is unbelievable loud, very low in
>> > > pitch, and sounds just like wind noise on a microphone. Seems to happen at
>> > > random times although more common when someone is playing it. Volume
>> > > control position has no effect on the noise volume but does sometimes seem
>> > > to affect the timbre of the noise. It goes away when you plug headphones in
>> > > (you don't hear it in the headphones).
>> > > Without the benefit of a service manual/schematic, I have tried to trace the
>> > > analog audio signal with an oscilloscope to at least determine from which
>> > > stage the noise is coming. I'm suspecting it's originating in the power amp
>> > > section - the amps are IC "bricks", one for each channel but since it's in
>> > > both speakers equally I'm thinking it's not them. Due to the sheer volume
>> > > of the noise it actually loads the power supply to a point where signals at
>> > > all stages are affected. I did change the filter cap in the dc supply. No
>> > > improvement.
>> > > I did read some newsgroup accounts of noise in the Clavinovas being due to
>> > > dirty contacts in the volume control... I'm picking up some contact cleaner
>> > > today and will try that but I'm not too optimistic about it.
>> > > Any experience with this problem or guidance much appreciated. >> > > Mike
>> Incidentally it also happens with headphones so Im a bit flummoxed. Oh and btw I have a CLP-440. Next stop Yamaha
>Oh damn my church piano developed this issue too a few months ago, and it's been driving me crazy!
Check for degraded adhesive used on pcb assys for vibration defense.
Remove it and clean the area with alcohol, anywhere it comes into contact with board traces or connector terminals.
RL