To observe the supply and the standby indicator light. Press the standby button on the remote control can't boot up. 4tgservice manual download site
 4tgservice manual download site
Action by fault phenomenon doubt protection circuit. In order to determine which part of the circuit is the cause, measuring the electrode resistance of bidirectional thyristor Q801 first, found no breakdown phenomenon of short circuit. Boot, measuring Q801 control voltage, there are moments of obvious swing, at the same time, along with the "cut" (voiced by relay release), and the voltage drop to 0 v. This judgment, Q801 control got abnormal trigger voltage make Q801 conduction state, rectifier filter circuit into a doubler rectifier, caused the doubler rectifier protection circuit. Failure in ac input should be the automatic switching control circuit. In turn D817, Q854, D815, Q853, R823 D816, resistance, such as components, found Q853 c and e a very open, R - 823 open circuit. Replace the 2 sc1685 and R823 Ω after (33 k). Troubleshooting.4tgservice manual download site