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My LG TV 55lv5500 suddenly turn black with no sound or picture.

My TV turn black with no sound or picture. The power light is on. I openness the back cover and it seems all capacitor are in working order. Do I need to replace the BU board or power supply

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Have the same TV....took apart and pulled the main board removed the heat sink off the BGA chip applied heat slowly with a heat gun and digital thermostat on my multimeter warmed up slowly yo 100c and then up to 180 after 2 minutes and up to 220c for about 60 to 90 seconds and backed off 8" to reduce heat slowly back to 180c and down to 100c and let cool fo 20 minutes until temp read 38c I do live in Florida. Reinstalled the oars added power and sure enough powered right up. Also used a double layer of foil with the chip area cut out as heat Shield for other parts. Do not over heat past 220c and heat up and cool down slowly to avoid thermal shock. Make sure your power supply is working.

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jpwinarto this sounds more like a power board issues. You do want to start by checking the power board voltages. Post some images of your boards with your question by using this guide. There are two different power boards depending on the type of LED backlight.

Block Image

and

Block Image

check the connector (red rectangle) to see if you get those voltages:

1 Power on

2 20V (24V)

3 20V (24V)

4 20V (24V)

5 GND

6 GND

7 GND

8 GND

9 3.5V

10 3.5V

11 3.5V

12 3.5V

13 GND

14 GND

15 GND

16 GND

17 12V

18 Inverter On/off

19 12V

20 Lamp : A-Dim LED : N.C

21 12V

22 PWM Dim #1

23 NC

24 Error-out.

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I replaced my LG power supply with brand new power supply and still no picture. Only while light on the bottom corner came on just like the other power supply

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Hi.

I had the same trouble on a 42LX6500. TV powers on, but no video, backlight or sound. Nothing.

Checked voltages and power-on signal as explained by oldturkey03 but voltages were correct.

So, I decided to reflow LGE3556C under brown heatsink and it is working now. A professional reballing should solve this definitely.

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I have the same problem on my 55LW5600.

I have checked the voltage on all pins.

Strangely, I get the 3.5V & 12V readings, but no readings on the 24V pins (2, 3,4)

I am getting 3.5V on the main power pin (1).

Can replacing capacitors fix this or is the board shot.

Also, when I turn the TV on the red light flashes twice and turns blue.

I don't see the LED lights for the edgelit LED's and screen is blank. Tried the flashlight test.

Thanks all.

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OK...brain fart. Didn't change the voltage range on my multimeter.

Power board is good. All voltages are as published.

How do I check the other two boards.

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jpwinarto will be eternally grateful.
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