To determine the fault range, the VCD signal is entered in the AV state, indicating that the machine is in the AV state.. The machine uses a Panasonic CX1/MX-3C movement, belonging to the I2C bus of the single processing chip (AN5192K) AV / TV, conversion, and not by converting circuit of peripheral AV / TV conversion, test access bus maintenance state, no items were found for the AV / TV conversion, try to cancel the hotel mode of operation, still can not solve the problem. Due to the adoption of the AV / TV button on the remote control or machine panel can make the conversion and character display is normal, the CPU judges without fault, the monolithic processor chip, the internal video switch has been connected to an external video signal to connect the internal blind frequency signal. Replacement AN5192K - B test grating appeared snow noise, resume normal automatic search, sound, image slightly purple, access to the bus and re adjust the white balance after troubleshooting.