Few days ago, i've been trying to repair this receiver I bought in non-working order. The thing is when you try to switch on, power relay clicks, CD/DVD appear on the display, and that lasts for about 3 seconds, and device shuts itself off. Already got service manual, and tried to enter diagnostic mode, and in that condition I discovered there is DC protection activated. But, there was no dangerous voltage on speaker terminals, what would make sense in this case, but voltage is normal. Checked all voltages on output transistors, everything seems to be ok, and even i hear sound if i put headphones. It is possible in diag mode to switch on and off speaker relays. Didn't try to put speakers, but my guess is I would get sound without any problems. As I figured out, DC protection is achieved when there is voltage outside normal on pin 91 of microprocessor. Value that is written on display is DC 000, which would suggest there is no voltage at all, at pin 91 (signal called PRD, DC protection). I should have 1.7V at that pin, and I have 0V. On schematics, I saw there is one capacitor connected to that PRD signal line, and it is C147 100uF/6.3V. I don't have voltage drop on that capacitor. Even, there is very small resistance across terminals, around 13 or 14ohm, so I thought capacitor is not ok, but turns out, when I wanted to replace it, suddenly I couldn't measure that low resistance across terminals any more, but anyway i replaced it, to know for sure that it is not the problem. Then I realized maybe something else making that low resistance across terminals, maybe some other board, so i tried to disconnect one, by one board from the main one, to see if that would make a change, and it didn't. And it was second time to disassemble everything, and first time i had -0.6V on positive terminal of capacitor C147, but later there is only 0V. Checked a lot of transistors in that area, didn't notice single one with problem. What could possibly go wrong if i can get sound in diag mode?