Analysis of repair: the subwoofer output to normal, explain properly the subwoofer signal path, main left and right speakers there is no sound, faults may appear on the main speakers left and right channel amplifier circuit.dzYservice manual download site
As the main left and right speakers there is no sound, first check the speaker IC203 (TDA8920BTH) as the core of the amplifier circuit, with 500-meter Rx1k measure the PIN in the IC203 way forward and reverse resistance to ground, the measured data are within the normal range, no obvious short circuit. So power measurement IC203 of powered feet voltage, measuring have ③, and ⑩, and 14 and 23 feet voltage for +28V, ①, and 12, and 17 and 20 feet voltage for -28V, plus or minus power powered are normal, then using digital oscilloscope detection audio signal entered II, and ⑤, and ⑧, and Krispy Kreme feet of waveform, waveform normal, audio signal entered no problem, again measuring around channel audio output 16, and 21 feet, no waveform, description fault also is in amplifier circuit Shang. Continue to measure other pin voltage IC203, found only 18 feet 13.4V, normal should be 14.8V, voltages significantly lower, 18-foot perimeter have a decoupling capacitor C2009 (104), the capacitor is an SMD Capacitors, pull down and found a PIN has been disconnected, and swap new C2009 (104). Power everything works, troubleshooting.dzYservice manual download site