Power on button operation and display are normal, any track under any decode status, there is no sound output. Observed output relay is snap. Maintenance: after measuring amplifier work correctly, disconnect the input plugs, enter additional audio signals to sound. The voltage marked on the measurement signal processing Board is also normal. Oscilloscope signal, electronic switching circuit IC301 sent signals after the switch to the main control board, was flat on the plate at the bottom, from the Board's output socket P205A 1, 4 feet to the volume control panel, labeled TOLI/TORI.4SHservice manual download site
4SHservice manual download site
But Jack P205A is not coming from the audio output connector output. Analog signal, select the normal channel and decode mode, volume control IC Q3171 (M62447SP) input signal input terminals 16 and 18 feet, output of 31, 32, 33, 34, 35, 36 feet, respectively R/L/SR/SL/C/SW under the volume control also has a normal audio output, suggesting the signal switch in front channels are working properly. These signals are sent to the Q3180/Q3181/Q3281 amplifiers, such as zoom in, to the rear amplifier Panel. But there are transistors Q3183 and Q3283 as mute control tube, measured for the base 3.5 volts, and pipe work in off status, has the two signals to ground, muting,4SHservice manual download site
4SHservice manual download site
Its base voice soon after. Indicates that the machine is no sound because of muted, P205A TMUT feet this signal comes from, tracked AMUT feet of the front panel, then there is no action to the mute button will mute it? This Onkyo amplifier repair is a relatively rare phenomenon. Observed the Onkyo is the first design of a DTS decoding machine, in 555 by adding a decoding board layouts, mounted on the front panel, it is clear that this was not originally designed. Decided to rip up the decoder Board. Remove the rear stumbled, there are few traces of corrosion on the front panel, place under a magnifying glass lines have rotted, and commissioning sound mute control signal disappears after treatment returns to normal.

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