I would like to try to diagnose and repair a receiver myself. The prices quoted by repair shops are higher than buying a comparable receiver new. It is a Pioneer VSX D811S. After playing at a high volume for a time it made a quick chirp and died. Now it will turn on for a few seconds and then shut off. The display does not light up and it does not make any sound other than a click (like a relay). I have checked the fuses I have found inside. If no one here can help perhaps someone can direct me to a site that can. Thank you.
well its pretty hard to diagnose something like that without physically seeing it. if your amp shut off while playing at high volume, my first guess would be your power amp chip has fired and shorted out. however if you're not getting any display, then it might be an issue with the power supply circuit. check the underside of the circuit board for any burn marks indicating a fried component. next thing I would do is test your power transformer.
there are two sides to a x-former. the primary side, which should have 120 volts AC going into it (provided you line in the US, europe is 240.) the secondary side could have anywhere from two to ten wired coming off of it. using your voltmeter, set it to AC volts. take one lead and connect it to ground (the metal from of the receiver.) now go through each wire with the other lead and check for voltage. it should be anywhere from 5 volts to 48 volts.
Invalid test.. shorted rectifier will drag TX voltage down.. as will shorted rfi caps across any one of the diodes in the bridge. Unless you can find the right schematic for the equipment, and know enough to read and understand it.. you will be 99% wasting your time. Failure of modern amplifiers follows a pretty standard pattern.. Output coupling capacitor shorts..(because they are cheap under rated components) causing the output device to draw excess current and short.. overheating the short in the capacitor (apparently) clearing the connection between the 2 foils.. while this goes on the over current sensing setup in the psu will kick in killing the main power rails.. sometimes these aren't fast acting enough.. and that blows the bridge rectifiers, or the voltage regulators, or the thermal link in the transformer.. or all of the above. So you fix it.. and as soon as things start getting loud the faulty output capacitor (which tests fine on a meter) shorts again repeating the process.
Take it to somebody who is competent.. the repair shops know how expensive these things can be to fix and a quote is always a worst case scenario. Find the schematic and post me a link and I will be happy to make some suggestions about what to test and how.. A small warning.. ONE output pair chip (I have an old aiwa 100wpc amp with blown outputs) can run to more than the cost of a used working amp.
