Fault phenomenon: When the AV has no signal, the screen turns blue and then goes black from left to right. The upper part of the screen shows a noticeable retrace line, while the lower part of the screen has about 3 cm of missing scan lines. There are also light white snowflake-like dots on the screen.
Repair process: The original fault was related to the high-voltage power supply. This issue occurred after replacing the package. The upper part of the screen had an obvious retrace line, and the lower part was missing around 3 cm of the image. Since the field is powered by the high-voltage package, I initially suspected a problem with the field power supply. Measuring the field power supply, the 2nd pin showed 13.5V, the 4th pin showed -13V, and the 6th pin showed 14.2V (the schematic indicates ±15V), which were all slightly below the rated values. On the magnetic side of the high-voltage package, each winding had only one turn. The positive and negative field power supplies were increased by 1V, the boost diode and capacitor were replaced, but the fault remained unchanged. Then, I noticed that the screen was shifting left and right, suggesting there might be an issue with the horizontal scanning circuit. I checked the connection between pin 34 of the block input and pin 4 of the high-voltage package, and all components appeared intact.
When testing with AV2, the image looked normal—no retrace lines, even lighting on both sides—but the field was reduced by about 3 cm, and the picture seemed a bit dizzy.
Is it a major hardware failure? Maybe the image can be normal without issues, but could it be a data-related problem? The sweep line seems unable to pull data properly, but I still wrote some data, and after that, the TV worked normally.
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