Clavinova CVP-55 OPTIONAL IN RCA's noise


My old but immortal CVP-55 has a problem since 1991. Never used OPTIONAL IN RCA’s had/has ground noise. Now I have an MU-90 and I can’t connect it (not mp3 or another home equipment too).

I have done a visual inspect into the Clavinova. Capacitors, etc… all is in good state, visually. My DM board is a VK555500 but I know it is a newer VL978500.

I like to know If i can repair my DM board (or the amplifier boards) or if I have to get a new DM board. I don’t know how to repair this issue.

All the story is here:

Thanks a lot!

My first thought is that perhaps you are getting ground noise from the way the two pieces of equipment are plugged into the AC outlets. Does this happen when both the CVP-55 and the MU-90 are plugged into the same AC outlet? If the CVP-55 has a grounded (3-prong) AC plug, try using a ground lifter, and see if that eliminates the trouble.

Hello Sam, sorry for the delay. The CVP-55 has not grounded AC plug. The issue is present If both are plugged into different AC outlets. I think is an internal issue, but don’t know where (Dm board or amplifier board).

But does the issue still happen if both are plugged into the same outlet? Plugging into different outlets can introduce a ground hum that might go away if both are plugged into the same circuit. You’ll want to eliminate that possibility before trying to figure out a repair.

Yes, the issue happen in both situations.

The noise is not from AC plugs, in my opinion. When a RCA cable is plugged into the optional in, the noise appears. The cable can be plugged only to Clavinova and not to the other side equipment and the noise is present. I checked visually all, no de-attached cables, not bad grounded pieces,… The noise is very loud ground noise… It is a mystery.