Analysis and Repair: When the machine is working normally, the power indicator light is green, and after remote shutdown, the power indicator light turns red. When auto-shutdown occurs, the power indicator light remains green, indicating that the remote control circuit is basically normal. The main power supply voltage of 115V is measured as normal, but the negative pressure at the base of the horizontal output transistor is 0V, indicating that the horizontal oscillation circuit has stopped oscillating. The voltage at pin 37 of N300 is measured to be 0.4V, which should normally be 0.7V; the voltage at pin 36 (horizontal oscillation power supply) is 8V, which is normal. The anode of V903 is measured to be 0.5V, whereas the normal voltage value should be 3V, indicating a fault in either the power supply circuit or the horizontal scanning circuit, causing V903 to conduct and resulting in automatic shutdown. After disconnecting the horizontal scanning circuit and connecting a dummy load, the main power supply voltage is close to 200V, confirming a fault in the power supply circuit. Upon checking R530, it was found that the solder joint was oxidized. After cleaning and resoldering, the fault was eliminated.
Source of information: Beijing Hisense TV Repair Center http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3764590.
Hisense TC-2156 TV, automatic shutdown after some time.
Fault Phenomenon: Normal when initially turned on, automatic shutdown after some time.
Circuits Involved: Power Supply Circuit.
Fault Location: R530 Solder Joint Open.