Yamaha Clavinova CLP-735 Sound Cutting Out — What Could Be Wrong?

Synth Repair
1

I’ve been having a frustrating problem with my Yamaha Clavinova CLP-735 digital piano. After playing for a short while, the sound suddenly disappears completely. The piano itself stays on and seems to work fine — the keys respond, the display is normal — but there is just no sound coming out.

If I turn off the piano and leave it off for some time, then turn it back on, the sound comes back and works normally. However, this fix is only temporary because after some playing time, the sound cuts out again.

From what I understand, the issue might be related to the main board, since the sound amplification stage is integrated there. So, if the main board is faulty, replacing it could solve the problem.

I’m wondering:

  • What could be causing this intermittent sound failure?
  • Is replacing the main board the only solution?
  • How much could the repair cost?

If you’ve experienced something similar or know about this model, I’d appreciate any advice or suggestions. The piano doesn’t shut down or freeze, it’s just the sound that disappears — which makes it confusing and inconvenient.

Thanks in advance!

2

It sounds like something is overheating. Before changing the entire board maybe do some testing with a multimeter and check it’s transformers for the correct specs. Something used over time is going bad causing a loss of sound. It could be a bad VCA chip. It could also be the power supply main transformer beginning to go bad. Notice to see how hot the machine’s (outer body) feels when you loose sound and turn it off. See if it’s outer body is feeling very hot or warm to the touch.especially it’s rear. I’m not sure if it’s got a fan in it that may have died. That used to happen to the power supplies on the Soundcraft Ghost recording console power supplies. The motor on the fans would die, power supply transformer would overheat and shut down. Hope you figure it out.