Sony STR-DB930 receiver goes into protect mode. No earlier symptoms, no prior intermittants.
I picked up the Sony factory service manual for this unit and, while it contains good schematics, little is offered in terms of troubleshooting info for diagnosing the "protect" fault.
- I read about the grounding issue and while I found this doubtful I'll give that ago later today not expecting a quick fix for this issue.
- When in protect mode, what is the nominal voltage reading that should be on the external speaker connection points? (I suspect zero since the relay controlling the outuputs would be zero).
- What should be the voltage reading be on the input to the speaker output relay?
- The Protect circuit appears to monitor voltage and also seems to be connected to current measuring circuits on each output channel. It seems to look at a number of potential problems but then offers little in the way of a back trace to root cause. If anyone could offer a few starting points to assist me in diagnosing the fault that would be great.