Check the AV input is normal, open the machine cover boot after a few minutes to touch its stereo decoding hot box, the television sound processing circuits of this machine is: the audio signal from the IC801 of 1 foot, sent to the stereo box of 12, 13 feet, and then out of the 15 and 16 feet of the stereo box to IC1301 22, 25 feet, AV switch IC IC1301 is controlled by the CPU. Then we will sound line (from 1 c801 1 foot) with a 10 uf capacitance across 15 and 16 feet from stereo box, audio, considering it's difficult to find and stereo decoder expensive this functionality is temporarily useless, so it will soon be removing the stereo section code box, the stereo box of 12, 13 feet jump straight to 15 and 16 feet, commissioning found only need to wait about 15 seconds sound appear normal, and in this way, every time you change channels, we analyze the circuit, the stereo codec is controlled by the IC bus, so according to the characteristics of IC bus at every boot, or conversion channel when the CPU is articulated on the bus IC for testing, if found in the detection of a IC didn't respond to a signal, the CPU will be repeated for detection of this IC, this makes the process of time increase greatly, so this phenomenon. Careful analysis of the circuit structure of stereo box, we found it inside circuit divides two parts, one is the digital processing part, one is the analog signal processing part, part of the digital power supply for 5 v, the analog part of the power supply is 9 v, we try to simulate part of its power supply disconnect (disconnect stereo box 11 feet, the purpose is to stop the analog circuit part of the work and the digital part back to work.) Mount stereo box to commissioning, everything is normal, hand touch stereo box is no longer soup, suggesting that this stereo box of analog signal processing circuit is damaged and the digital part is good, after such processing machine back to normal after use.Lwvservice manual download site