Preliminary judge circuit failure in the public channel. Oscilloscope for monitoring N10117 foot fault video flashing light signal at the output, audio power amplifier N201 (TDA1013) >25Vp-p II foot moments at the output amplitude of line retrace pulse fault shrinks to the output circuit. Suspect that a component connection is bad, but almost all of the welding output circuit-related components, the failure has not ruled out. Percussion line output transformer T502, instant on, screams, suspect Flyback transformer internal connection is bad, but fault still after you change it for a new one. When a row between tube shell heat sink external radiator after joining the MICA insulation, they formed interelectrode capacitance, capacitance is very small, but row tube c 800Vp-p return high pressure above, the voltage is still available through the interelectrode capacitance discharge. Because line pipe heat sinks poor grounding that makes line retrace pulse interference caused by high voltage discharge to ground.