Image and sound is normal, and also the characters beating, indicating that the normal work of the relevant circuit, fault reason has two possible; one is character formation and display circuit for sealing off or breaking point, resulting in poor contact; the second is component performance, work is not stable.

A place for the fast fault diagnosis, take the test method to determine the dynamic voltage (see photo). First in the CPU (39) the feet and the ground end of the welding to wire and connected to the multimeter block concatenation 25V boot, failure to observe the change of voltage.

When the fault occurs, the voltage is normal and stable, which indicates that the fault is not caused by the abnormal position of the line. And the CPU (39) foot of the welding wire to weld in (55) feet, the test machine, at this time, the foot voltage fluctuations. The preliminaryjudgment fault circuit in the presence of synchronous pulse echo. Power outages after welding, the welding line, carefully check the CPU (55) feet to the field block output IC452 (7) feet between the circuit and related components, first check connector DLL / X1 (6) feet and A2/D2 feet (8), found A2/D2 (8) pin socket connector has oxidative blackening. To scrape the net and wash, and the DI1 / Xl (6) foot and foot and foot to the same time, the test machine troubleshooting.