Fault symptoms: The TV turns on with a raster present but no image, no sound, and neither the remote control nor the panel buttons function properly.
Sharp TV, both remote control and panel buttons are ineffective.
Source of information; Beijing Sharp TV repair phone: http://blog.sina.com.cn/xiapudianshi.
Analysis and handling: The fault symptoms of this TV indicate that there may be an abnormality in the high-frequency or intermediate-frequency circuit, or in the remote control system controlling the channel search circuit. The microprocessor of the remote control system for this TV is the N901 (M50436-560SP) integrated circuit chip. Upon checking, the required auxiliary circuit supply voltages of +5V and -30V were found to be normal. Further inspection of the voltage at each pin of N901 revealed that the voltage at pin 30 was +4.5V (which should normally be +4.9V), slightly lower than expected. After disconnecting the peripheral circuits, the voltage at pin 30 returned to normal, clearly indicating issues with components related to pin 30. Using a multimeter to check the relevant circuit components, it was found that L901, R970, and V009 were all normal. However, upon carefully checking the panel button switches with the multimeter, it was discovered that most of them had leakage current issues. Replacing the panel button switches with new ones, the TV was then powered on for testing, and the fault in the color TV was resolved.