Konka color TV P21TK828 three trouble-free maintenance - Home Appliances

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Fault model: Konka color TV P21TK828
Fault phenomenon: Three trouble-free maintenance steps were taken. First, a visual inspection showed the fuse was intact. The main filter and B+ voltage were measured, and no short circuit was found. When the main power was connected, the voltage reached 300V, and B+ was 48V. However, the power indicator still didn’t light up. Further testing of the optocoupler showed 1V on pins 1 and 2, which indicated that it was functioning properly. Since the B+ voltage was low but not related to the power supply issue, it was suspected that the CPU power supply might be faulty. Next, the voltage at pin 8 of the memory was measured and found to be only 0.5V. After checking, there was no short circuit between pin 8 and ground when the power was off. A back-test of the switching power supply revealed a 6V output from the CPU power supply group. Upon close inspection with a magnifying glass, a fault was found in N952 at pin 8. After repairing this component, the optocoupler was restored, and the TV returned to normal operation. [attach]438324[/attach]