According to the phenomenon that the power supply system is good, including: 35 v, + + 18 v, - 18 v, + 15 v, + 140 v output is normal. To rule out impossible factors, for narrowing the scope of the fault. Causes of black screen are: 1, line didn't rev, line output transformer without each voltage output. Line 2, rev up, high pressure, accelerometers, filament voltage is not normal. 3, R, G, B to visual processing circuit, in the off state. 4, for LR, LG, LB plate lost the + 12 v, etc. pgMservice manual download site
 pgMservice manual download site
 pgMservice manual download site
 pgMservice manual download site
"Hope" first, no obvious burned-out component, filament is not bright. "Smell", no peculiar smell, after startup without high pressure build up sound. "Q", the user reflect occasionally encountered in the process of using black screen, shut down after heavy boot is good again, now has been blank screen. According to the analysis of the filament is not bright, without a sound and vibration, the vibration check line rev should begin. "Cut", + 140 v added to pipe, pipe base no voltage, line haven't rev up right. According to experience, D465 zener diode short circuit is more, cause IC459 does not work, DG board of 28 feet output lines of excitation signal cannot reach, driven by measuring, D465 is normal. 28 feet of DG board, again no voltage output, thumb DG bad caused more should be DG plate, plate by the door, no DG board confirmed. DG plate repair is difficult, in the user home repair and no longer line, you can't measure the internal voltage, maintenance in trouble. Decision from the periphery of the socket, each foot bus of DG plate, and the power supply voltage, power supply is only 0.8 V, 3.3 V 35 feet the voltage produced by IC2705 voltage stability, disconnect the DG plate 35 feet, measuring 3.3 V is still not normal. That DG board is good, almost miscalculation. IC2705 measurement input voltage is normal, no obvious short circuit output, doubt IC2705 adverse, the less bad, and no spare parts, C2709 and IC2705 model, decided to switch, remove the rough idea of quantity, no difference between the value and estimate is good, look closely, IC2705 have black dirt formed between pin, there may be caused by leakage, cause no output, recovery after cleaning circuit, troubleshooting.

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