This machine fault is the original "blue screen" and a flyback line. Once received signal (either TA or AV status), is automatically converted to "black screen" and no character display, but there's a light at the end of the shutdown instantly. 4zvservice manual download site
 4zvservice manual download site
According to the fault phenomena analysis, when a signal is input video channel. Measuring video/colour/scanning and small signal processing integrated block M52340 (21), (22), (23), foot (R, G, B signals output) are around 2.5 V voltage (3.4 V) normally, the replacement after the problem remains. So if the CPU is not normal work? Press the panel TV/AV key, at the same time, measured the CPU (M37220M3) (30) foot (AV/TV conversion control) of the output level is high and low, that means the CPU working conditions (power, crystals, reset, button scanning)) basic normal, and in the press TV/AV key, measure the CPU (37) foot (SCL), foot (38) (SDA) voltage is 4.8 v, this shows the CPU work basic normal, there could be a failure condition is not satisfied. Must have the character display, is one of necessary conditions for line, field flyback pulse to locate, so whether the two pulse has reached the CPI. J? First measure the CPU (1) the foot (h. SYNC) waveform, indeed as expected no conduct flyback pulse signal waveform, ultimately, is found to line flyback pulse transmission circuit in the clamping diodes VD801 breakdown (8.2 V). After the replacement, troubleshooting.4zvservice manual download site