This machine uses Toshiba 's new monolithic integrated circuit TB1240N, AV signal input , sound normal , the fault in the initial judgment sound demodulation circuit . TB1240N {53} feet from the sound IF signal input inject interference signal , speaker interference noise , { 55 } feet from the sound IF signal output inject interference signal , but no interference noise . { 55 } feet measured voltage of 0.1V, 3.6V and normal that much difference , so { 55 } feet dangling , the voltage is still 0.1V, { 4} feet measured its quasi- separation of audio signal input voltage 5V normal judgment TB1240N internal partial damage . This can not be purchased locally to the manifold , drawing closer look and found that this machine Sound System D / K (6.5MHz), I (6.0MHz) using quasi- separation method to separate the audio signal and image signal, and M (4.5MHz ) made ​​in the carrier system using audio signals separated from the image signal. Then try the "×" at C265A and TB1240N {55} feet off , and Q251 e pole solder connections on a boot sound normal.4Qbservice manual download site