Hi looking for some advice. My Technics system has stopped working. There is power to the unit, but nothing is playing and my brother thinks it might be the amp (SU-CH7) which is faulty. Could someone please advise us on troubleshooting the amp? Many thanks

 

Here's a start.

It has a fuse, a circuit breaker, and 3 secondaries on the power transformer. Start measuring DC voltages to see if the power input section is good.