This machine adopts Toshiba Co monolithic integrated circuit TB1240N, input AV signal, sound normal, fault in the preliminary judgment audio demodulation circuit. Injected from the TB1240N{53} foot Sound IF signal input signal interference, speakers have noise, injected from the {55} pin audio intermediate frequency signal output end of the interference signal, but without the interference noise. The {55} pin voltage is 0.1V, and the normal value of 3.6V is too large, so that the {55} feet vacant, the voltage is 0.1V, the {4} foot sound separation signal input voltage of 5V normal, TB1240N internal partial damage judgment. The integrated block local not to buy, look at the drawings, found the machine sound system D / K (6.5MHz), I (6.0MHz) using quasi separation to separate the sound signal and the image signal, and the M (4.5MHz) system using carrier separation sound signal and the image signal. So the "X" C265A and TB1240N{55} feet off, and Q251 e arc welding a connection, the boot sound back to normal.xgqservice manual download site