Observing good watch everything is all right; Abnormal, boot after hear machine with the sound of "zhi", the power indicator light shine it out with the voice of "zhi" disappear, sometimes multiple consecutive start is not successful. 27dservice manual download site
First measured C909 on both ends of the capacitor boot instantly changes the voltage of 110 v, found the voltage swing, approximate to zero volts. Measured again C906 capacitor 280 v voltage is normal. Disconnect the load circuit, make a holiday after 7.5 W electric load, boot failure remains, judge fault occurred in power supply section. According to circuit principle diagram analysis, the protection circuit branch resistance R907 disconnect, this time don't pick up the load, boot test 110 v voltage return to normal. When connected to the load circuit, a short period of time monitoring the voltage is normal. For Q902 SCR and peripheral components measurement inspection found no problem. Through the analysis, the cause of the problem may be the biggest SCR performance becomes poor, lead to cause power supply protection. In models with silicon controlled rectifier, troubleshooting, the TV back to normal.27dservice manual download site