Open the TV shell, fault self-healing, suspect poor contact fault circuit, may open welding joints for the repair welding. And a half years, the recurrence of similar failures several times, due to the teardown self-healing, fault has not been completely ruled out. The last time, and the failure of teardown fail to heal, created opportunities for maintenance. Measuring voltage + B, boot instantaneous voltage 140 v, and then to 0 v. Measurement D819, trigger voltage Q856 protect circuit and microprocessor fracture in voltage, found D819, Q856 no trigger voltage, only the microprocessor IC1213 6 feet for high level, judge peripheral fault detection circuit is the microprocessor 6 foot protection. JR5service manual download site
 JR5service manual download site
 JR5service manual download site
Out fault detection circuit protection method is used for maintenance, disconnect the microprocessor IC1213 6 feet outside the line output overvoltage detection circuit D553, boot out of protection, and light, sound, graph are normal, judgment is line overvoltage protection circuit fault, the error protection. Inspection on line overvoltage detection circuit, the resistance partial pressure circuit is no exception, measure the zener diode D554 voltage value is within the normal range, final inspection C555, C567 bleeder circuit, found C555 surface crack, remove the C555 measurement, there are about 50 k Ω instability of leakage resistance, due to the partial pressure value is not stable, the error protection. After replacing c555, restore protection circuit automatic shutdown fault won't happen again.JR5service manual download site