This TV that came in for repair was found to have a Horizontal Output Transistor D1878 (on board location Q522) with a short between the collector to emitter. When the defective transistor was pulled out of circuit there was still a short measured from the B+ line to ground. The deflection yoke was unplugged from the TV's main board but still the short was present.
Tracing back towards the power supply it was found out that a shorted RU3A diode on board location D921 is shorting the B+ line to ground.
Replacing the transistor D1878 and diode RU3A restored power and normal operation to the set.
JVC TV AV-J21MX KEEPS ON BLOWING THE LA 7837 VERTICAL I.C., AFTER AN HOUR OF USING, BUT NOT AUTOMATICALLY BLOWS THE VERICAL I.C. WHEN INSTALLED, HELP...
ReplyDeletePlease check if the vertical IC you are using is an exact replacement. Also make sure the IC is mounted tightly to the heat sink.
ReplyDelete