A panasonic TC - 33 v30h image content for bright color TV show, the grating amplitude essentially normal, but the image content for the dark images (at night), grating amplitude of narrow, about 1 cm black border around the screen failure. Obviously, this is high voltage stabilizing circuit malfunction caused by grating heaving. First disconnect R1501 sampling the input resistance, no the same failure phenomenon, that is, indeed, high voltage stabilizing circuit does not work. R1501 recover next, adjust the sampling resistor R1551, found that the horizontal amplitude grating indeed change (maintenance later found, in fact, this is Q1503, Q1504 sent to horizontal pillow correction circuit dc level cause line deflection coil current is caused by a change). Therefore, amplification of high voltage circuit is normal, problem could be in the output stage. After the check, the magnetic saturation reactor L1514 windings without breaking phenomenon, the output tube Q1501 c very (normal) should be 8.4 V, 12 V voltage obviously did not work. Test the b is 4.4 V voltage (normal is 4.3 V). But normal welding under 01501 check,. E ready to test next extremely negative feedback resistance R1517 Ω (56), found a ring obvious solder joint crack, after repair welding of commissioning, troubleshooting.paDservice manual download site