LG 65UB9200 no image or sound

[Jtroutt19]

You can hear the initial click from the power supply when you hit the power button but there is no image no backlight and no sound.
Less than 1v per led pin at the connector for the backlight.

When the unit is on voltage at the main board connector is good. There is a small red led on the power supply board towards the backlight connector. It flashes 5 times and then pauses for about 7 seconds before flashing again.

Is the P/S bad?

[budm]

Re: LG 65UB9200 no image or sound

The connector on the power supply board that goes to the main board has pin name for each pin, we need top know what the Voltage are when the TV off and when the power switch is activated, you must put down the pin name and follow by the Voltage reading when TV is OFF and when power switch is activated so we can easily see what are missing.

[Jtroutt19]

Re: LG 65UB9200 no image or sound

Ok I remember being told that before now. Sorry. I will get that info first thing tomorrow.

[Jtroutt19]

Re: LG 65UB9200 no image or sound

ok here are Voltage for the main connector. First column is power off second column is power on.

Column 1 OFF:ON    Column 2 OFF:ON
SIN-    0v:0v     V-SYNC- 0v:0v
SCLK-   0v:0v      GND
GND            GND
24v-    0v:24.8v    24v-    0v:24.8v
24v-    0v:24.8v    24v-    0v:24.8v
GND            24v-    0v:24.8v
12v-    0v:11.78v   GND
12v-    0v:11.78v   12v-    0v:11.78v
12v-    0v:11.78v   12v-    0v:11.78v
GND            GND
3.5v-   3.5v:3.5v   3.5v-   3.5v:3.5v  
3.5v -   3.5v:3.5v   GND
P-DIM-  0v:3.38v    P-DIM2- 0v:3.38v
PWR-ON- 0v:3.43v      DRV-ON- 0v:78.2mV

[dick_barton]

Re: LG 65UB9200 no image or sound

Looks like the DRV_ON voltage from the mainboard is missing.
If you disconnect the mainboard from the power supply do the backlights come on?

[Jtroutt19]

Re: LG 65UB9200 no image or sound

No I hear a click from the power supply like it is turning off. Then nothing

[dick_barton]

Re: LG 65UB9200 no image or sound

With the mainboard disconnected can you jumper the 3.5V to PWR_ON using a 1K resistor and a second 1K resistor between 3.5V and DRV_ON. The Backlights should come on.

[Jtroutt19]

Re: LG 65UB9200 no image or sound

Yes back light does come on. I do not see any dim spot or anything. Looks great.

This mean I am looking at a bad main board correct?

Or would it be possible to repair the main board? What causes this particular issue?

[tvtimmy]

Re: LG 65UB9200 no image or sound

Lead free solder and corporate GREED cause this problem.