[TestSubject]

I have acquired a Blown Sony STR-DG500 Amplifier.
 
When pressing the power button a relay clicks, the LCD light up showing the input then the mode it is in (exemple concert) then a relays click again and the LCD blinks PROTECT. There is no load on the device or anything else connected but power.
 

 
Any idea?
 
 
 

The protect indication means the amplifier is overloading and has gone into protect mode.  This is a power management circuit that has detected excessive current or power consumption in the output stages.  The could be caused by a short on the speaker line, a shorted woofer in one of the speakers or dried out silicon grease on the insulating washer of the output transistor (which happens frequently in old amplfiers)

 

[HairyMerkin]

Post up some pictures of the actual circuits