Hisense plasma TV TPW4219H (LG V7) has sound without image troubleshooting - android - Phones Developers

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Hisense plasma TV TPW4219H (LG V7) turned on and the blue light is on, and the relay can be heard. The entire screen has a darker snowflake with full screen.

After the power is turned on, the blue light is on, and the sound of the relay is heard. There is sound accompanying. The remote control can be used to switch on and off. Basically, the non-digital board problem can be eliminated. According to the original fault of the network, the screen is not bright. After changing the Y driver board, this phenomenon is formed. Later, I changed the X driver board and the logic board was still faulty.

Using the screen self-test method can be judged as the screen main component failure, the self-test method is as follows:
The first step is to disconnect the digital board wiring socket and short the connection between the AUTO terminal and the middle pin of the switch SW601 (there are two groups). The new type power supply board (the heat sink is black) directly sets the toggle switch. At AUTO, the standby function on the main power board is cancelled at this time. R407 (0 ohm) on the logic board is soldered with a soldering iron, placed next to it, and restored after repair.
In the second step, the power screen is plugged in, and the plasma screen is illuminated. At this time, 56 white raster red gratings and color bars should be displayed on the screen. If the screen is abnormal or the screen is abnormal, the plasma screen main unit is faulty.
There is a self-test screen after power-on, but the screen has a darker snow-like dot interference on the full screen.
First check the VY and VSC voltages on the Y driver board. The check method is as follows:
Pay attention to the adjustment of VY and VSC voltage after replacing the Y drive board. The specific adjustment method is as follows: (1) Adjustment of VY voltage:
Detect the voltage across the R78 resistor as the VY voltage, adjust the VR4 potentiometer, and adjust the voltage to 85V;
(2) VSC voltage adjustment:
Detect the voltage across the R53 resistor as the VSC voltage, adjust the VR3 potentiometer, and adjust the voltage to +115V.
The inspection found that the VSC voltage was 115V normal, the VY voltage was 65V, and it was adjusted to 85V. The fault is still replaced with a new Y drive board, the fault is still the same, and the fault disappears after changing a logic board.
Finally, restore R407, remove the short connector on SW601, connect the digital board, boot everything is normal

The inspection found that the VSC voltage was 115V normal, the VY voltage was 65V, and it was adjusted to 85V. The fault remains, the R407 (0 ohm) resistor on the logic board is removed, and the self-test screen is energized, but the screen has a darker snow-like point interference on the full screen.
First check the VY and VSC voltages on the Y driver board. The check method is as follows:
Pay attention to the adjustment of VY and VSC voltage after replacing the Y drive board. The specific adjustment method is as follows: (1) Adjustment of VY voltage:
Detect the voltage across the R78 resistor as the VY voltage, adjust the VR4 potentiometer, and adjust the voltage to 85V;
(2) VSC voltage adjustment:
Detect the voltage across the R53 resistor as the VSC voltage, adjust the VR3 potentiometer, and adjust the voltage to +115V.
The inspection found that the VSC voltage was 115V normal, the VY voltage was 65V, and it was adjusted to 85V. The fault is still replaced with a new Y drive board, the fault is still the same, and the fault disappears after changing a logic board.
Finally, restore R407, remove the shorts on SW601, connect the digital board, and boot everything.