Yamaha YPG-535 no sound

Yamaha YPG-535 power up no issue, it can plays a few minutes then no sound, reset power.it plays again but only a few minutes then no sound again. What can go wrong? Any helps are appreciated.

Some Yamaha keyboards use a relay to mute the output until the machine is booted and ready. If yours has such a relay, perhaps it is going bad…? It might look something like this, about 3/4-inch long: