Hifi-trouble on Yamaha R840 module

Thread Starter

Didier C

Joined Jan 12, 2021
Hello everybody,

My son has a malfunction on his Yamaha Pianocraft R840 amp module, aged around 5 years; one channel is buzzing, a friend of mine told who has knowledges in electronics me that it sounds like half of push-pull amp is out.
Mys daughter who has some kind of same model had same kind of same trouble a few years ago and I red that this could happen quite often on that sort of equipment, as " usual suspects".
Does anyone know what could I do to repair? changing some pieces or even the entire board (if it is affordable of course).
Thanks for your suggestions.


Joined Dec 29, 2008
... Sometimes it is possible to find a bad part by applying 'freeze-spray' ... (It is sold in a spray can.) to any likely components and listening for a change in tone. Output transistors, parts mounted on heat sinks, or electrolytic capacitors could be tested in this manner. ... No guarantees, but it might be worth a try.