Yamaha RX-V563

[irobot]

This one has me baffled -

I Have a Yamaha RX-V563, when plugged in all DC voltages seem to be OK. (Power relay energizes as soon as it's plugged in.)

Main ON/OFF button has no effect. Speaker relays do not kick in. FL Display stays off, although voltages seem good on the controller, from about -24 to -29 VDC.

The LIM circuitry is functioning, when applying an external test signal.

This problem is very similar to a Yamaha RX-V361 that I'm servicing.

Both these units use the Sanyo STK433-03 and STK433-030 modules.

Thanks in advance for any help !

Mike.