The machine decoding block IC501 M51338SP - 3. According to the images appear left shift phenomenon, check IC501 pet-name ruby foot external line phase adjustment circuit element R710, R708, C706, C709 found no exception; According to image hair and issued a "hiss" sound and cause the phenomenon such as automatic shutdown, judgment line scan frequency self-excited failure may not be stable or exists. Check lines IC501 power filter capacitor, to promote the related element of line output stage and no abnormalities are found, try a newline, fault is still; According to the grating ZuoLiang right dark phenomenon, doubt blanking is not normal. Measuring IC501 line flyback pulse input dc voltage of 14 feet 7 v (icon normal lO. 6 v), using the oscilloscope measured the signal waveform (see figure 4 a) has been a serious distortion, and waveform instability (normal waveform should be as shown in figure 4 b). Measuring R703 C782, C785 line at one end of the flyback pulse waveform is normal, that waveform distortion happened between R703 and IC50114 feet. Check the related components, found D702 reverse resistance is not stable. After replace with 1 n4148, troubleshooting. xpLservice manual download site
 xpLservice manual download site
By IC50114 feet input line flyback pulse function has 3: it is as AFC comparison of horizontal frequency signal; Second, as the color synchronous gate; Three is a line of blanking. Therefore, in this case though fault with "l" cases belong to pulse clamp diode reverse leakage current, but due to the pulse signal role in AFC circuit at the same time, so the line frequency and cause instability and complicating fault.xpLservice manual download site