Symptoms:MDtservice manual download site
Boot display access signal how to operate and no sound. But found a strange phenomenon, no matter which connected a/b channel, boot it unless you press one, can not decode the selected way. Feel free to click on the a/b, decode mode can be selected.MDtservice manual download site
Repair procedure:MDtservice manual download site
This looks a bit like a program the disorder, first check the circuit boards look and found no damage, corrosion, etc. Measuring the operating voltage is normal. Measure CPU external crystal oscillator is working properly, working voltage, too. Access analog signals, signal has entered the conversion IC Q301, six-channel decoding output signals do not, the problem is in this integrated decoder Board,. Because of the high integration, brought no small difficulty to Onkyo repair work.MDtservice manual download site
First find the circuit diagram, and sort out the signal process of machine, Q301 is a switched circuit BD3817KS, straight into the analog signal and digital decoder, the signal output after switching to Q800 (AK4588VQ) as a signal source of analog surround, all output to the level interface. 45,881 receiving analog signals return to 3817 converts it to an analog surround sound, on the other hand received Q701 (IC42S494003CQ-Z) decodes digital signals. Power with help of mold found 4588 are fever, because the spot is more convenient, then substitution 4588, try machine unchanged, indicating no problem. Continue to see the circuit eventually 3817 RL were given due credits should 68/70 feet of various signal outputs, and RL signal is sent to 4588 3817 31/32 output to the foot of 51/52 feet. Output measuring 31/32 feet and 68/70 feet, the road outside mute transistor Q307/Q308, whose base is 3.5 volt, has been working for sound State, still no output after disconnecting. Suspect chip circuit, signal the player after receiving the 68/70 pin, the signal disappears. Try replacing 3817, try the normalMDtservice manual download site