Onkyo TX-SR8550 is a normal AV amplifiers, internal structure looks like my Onkyo's 5-series, decoders, erect on the right. Symptom: amplifier power supply without any instructions, press the power button nothing happens, LEDs do not light up. More Onkyo amplifier fault, please contact 023-68657783.Ek4service manual download site
Boot test: after the 220-volt AC plugged in, the standby power outputs 12 kV and 10 kV, with cable JL901B to Board, multimeters to measure CPU voltage of 5 volts is normal. Arrangement of JL901B is: 1.P OFF 2.+12V. 3.GND. 4.+10S. 5.POWERD. p OFF power control.Ek4service manual download site
According to user reaction, this machine bought two years has been rarely using, but has been no pulled had power plug, this Taiwan amplifier no Exchange switch, so from standby part began check, Chongqing district air wet has been is raised many fault of main causes, so should carefully observation machine within Circuit Board has no capacitor corrosion, and bulge, copper foil rust, and perforation,, and measurement all press did short-circuit and leakage.Ek4service manual download site
After above checks found no single point of failure, then measured from the CPU to start with, the CPU Model: M30624MHP-B06FP, located on the decoding Board radiator end General CPU work elements of the PA, including: operating voltage, crystal oscillator and reset voltage, voltage detection. Measure the PIN found that 12 PIN reset voltage only 1.2 volts, normally should be 5 volts, people-connect 5 volts to 12 feet, and boot normally. Control circuit diagram checks resetting circuit Q601 leakage, replace the machine back to normal after.Ek4service manual download site
Onkyo amplifier start-up mode is generally the standby power supply after the CPU, CPU instructions power on relay closing main transformer to power on, never apart protects main transformer because amp does not power on to get it fixed.Ek4service manual download site