Yamaha rx-770 manual - Yamaha RX-770

SOURCE: Yamaha RX-770 Receiver display quit

there is a bulb inside the backlight on the lcd display.it is 12 volt and alot of manufacturers run it from the +- 15 volt preamp power supply,on the plus rail.when the bulb burns out it can activate the dc speaker protect,or some other 12 or 15 volt circuit..if it is a flourescent display that is a different problem.those run on 5 12 18 and -32 volts.there is also a 6 volt ac filament voltage.you need the schematic.

SOURCE: Sometimes only one channel plays

It sounds like you know what the problem is. Get it fixed.

Or try this temporary fix.

Or turn it off and manually operate the selector and all controls a thousand times to wipe the apparent oxides from their contacts.