LG LCD no screen question


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LG LCD no screen question

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slper
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Aug 25, 2015, 10:30 PM

Post #1 of 25 (2418 views)
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LG LCD no screen question	Can't Post

Hello all, New here, Hellva way to start out on a forum begging for help but you are my last hope before throwing this TV out. My search capabilities here need help as well. :) My best guess is the TV received a surge from a lightning strike near by. The TV powers up and the blue light is on. There is zero back lighting and I can't see a menu screen with the flashlight test and has no volume. Is there any way to guess what needs replaced based on the info I provided? LG 55LD520-UA I see no burn marks on any boards, no blown capacitors, can't see any burnt diodes...

(This post was edited by slper on Aug 25, 2015, 10:50 PM)

jts1957
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Aug 25, 2015, 10:45 PM

Post #2 of 25 (2408 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

IF all power supply voltages are present, but there is NO Inverter ON command, Replace the Main board.

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Location: Far, Far Away

(This post was edited by jts1957 on Aug 26, 2015, 12:03 AM)

slper
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Aug 25, 2015, 10:52 PM

Post #3 of 25 (2403 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

Repaired my edit Tongue

I will check power. My guess it's there because it's powered up with a blue light. Does anyone have a good source for a part number and recommend a place to buy it?

Thanks in advance to you all!

jts1957
Veteran

Aug 26, 2015, 12:09 AM

Post #4 of 25 (2397 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

(Power sources) 'All of them?'

http://www.shopjimmy.com/lg/55ld520-ua More than 1 Main board was used for this model number.

Who? Me? Myself? or I?

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Location: Far, Far Away

(This post was edited by jts1957 on Aug 26, 2015, 12:11 AM)

slper
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Aug 26, 2015, 1:03 AM

Post #5 of 25 (2392 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

Of course it does. It's never something simple for me Smile

jts1957
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Aug 26, 2015, 2:16 AM

Post #6 of 25 (2387 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

https://www.youtube.com/watch?v=RwHTvjMdrhk

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Location: Far, Far Away

slper
New User

Aug 27, 2015, 12:29 AM

Post #7 of 25 (2368 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

Thank you, I will check it out this weekend.

slper
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May 16, 2016, 10:58 PM

Post #8 of 25 (2103 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

Ok, old thread, just getting around to repairing this TV. No backlight, nothing on the flashlight test. Do you think this will fix my problem?

http://www.shopjimmy.com/lg-ebr66474107-main-board-for-55ld520-ua.htm

jts1957
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May 17, 2016, 5:20 AM

Post #9 of 25 (2096 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

PS has ALL three voltage supplies (one or more may only be present when the PS receives one or both turn on voltages)?

And attempting to fix a problem by putting in a non-in stock board is a little crazy (unless you are only using that SJ item as a reference as to what your set uses).

Quote

The TV powers up and the blue light is on.

So when the set is OFF the blue light is also OFF?

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Location: Far, Far Away

slper
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May 17, 2016, 10:38 PM

Post #10 of 25 (2083 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

I was using the add as an example for a part. What is PS? Power supply? I'm only guessing based on watching vidoes and performing basic test. I have no other way to test. The TV is only 1.5 years old and I hate to throw it out.

jts1957
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May 17, 2016, 11:43 PM

Post #11 of 25 (2078 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

Pin functions are clearly marked on the PS board around connector P201.
A DVM to test voltages can be acquired locally for very little money (10 - 15 dollars).

I've given my opinion as to what I believe is wrong and how to narrow it down. If you choose NOT to listen, there is no more I can do.
The more it's narrowed down, the more sure you can be as to which board has failed. Then it's just a matter of obtaining a 'Good' board.

You never answered whether the blue light is acting correctly.

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Location: Far, Far Away

slper
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May 18, 2016, 1:09 AM

Post #12 of 25 (2071 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

Sorry for not answering the question. I'm not used to the format and lay out of this forum and it's hard to follow the flow of the thread. I will check the blue light tomorrow. <br>Thank you <br>

(This post was edited by slper on May 18, 2016, 1:11 AM)

jts1957
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May 18, 2016, 1:30 AM

Post #13 of 25 (2065 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

Edit Profile> Display Settings> Threaded (or Flat)

The only two ways of viewing that I'm aware of.

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Location: Far, Far Away

slper
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May 18, 2016, 10:06 PM

Post #14 of 25 (2051 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

Red light is on when the TV is off, Blue light is on when the TV is on. Thanks for the help! My Fluke meter is being borrowed and I should get it back soon.

(This post was edited by slper on May 18, 2016, 10:07 PM)

slper
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May 25, 2016, 12:03 AM

Post #15 of 25 (2026 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

jts1957, any more insight on the red and blue light? Thank you for all you guidance.

jts1957
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May 25, 2016, 2:15 AM

Post #16 of 25 (2023 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

In Reply To

Pin functions are clearly marked on the PS board around connector P201.
A DVM to test voltages can be acquired locally for very little money (10 - 15 dollars).
...
You never reported whether these (3 voltages) are present and the turn-on pins (PSON & BLON) are acting correctly.

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Location: Far, Far Away

slper
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May 26, 2016, 1:21 AM

Post #17 of 25 (2008 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

I will test tomorrow If I can find what to test based on what you have stated . I got my fluke back.
Thanks again.

slper
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May 27, 2016, 10:45 PM

Post #18 of 25 (1990 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

No power on any of the 12v sources/pins on P201

jts1957
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May 28, 2016, 12:40 AM

Post #19 of 25 (1989 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

Quote

No power on any of the 12v sources/pins on P201

When? In Standby? When switched ON?

Quote

(one or more may only be present when the PS receives one or both turn on voltages)

One down, four more to go:

3.5 Volts? There or NOT there?
24 Volts? There or NOT there?
PWR? There or NOT there?
INV-ON? There or NOT there?

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Location: Far, Far Away

(This post was edited by jts1957 on May 28, 2016, 12:45 AM)

slper
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May 28, 2016, 12:53 AM

Post #20 of 25 (1983 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

For clarity, when I unplug the plug from P201 the TV lost power so I kept the plug in and checked for power from the back side of the plug so the tv would stay on (blue light on).
I will check the rest.

jts1957
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May 28, 2016, 1:17 AM

Post #21 of 25 (1981 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

Plug ALL connector into their normal operating positions. Do NOT unplug unless told to do so.

You should be able to sneak a thin test probe (or wedge a resistor lead) between the plastic housing and crimped metal where each wire enters the connector. No need to even remove board mounting screws.

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Location: Far, Far Away

slper
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May 28, 2016, 11:48 PM

Post #22 of 25 (1969 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

3.5's there, 24v there, inv-on had.009 <br>

power there

(This post was edited by slper on May 28, 2016, 11:50 PM)

slper
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Jun 5, 2016, 9:39 PM

Post #23 of 25 (1876 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

does this confirm the main board is bad?

jts1957
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Jun 5, 2016, 10:55 PM

Post #24 of 25 (1874 views)
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Re: [slper] LG LCD no screen question [In reply to]	Can't Post

Quote

IF all power supply voltages are present (with set turned ON), but there is NO Inverter ON command (approx. 3 to 5 volts, when set is turned ON), Replace the Main board.

-------------------------
Location: Far, Far Away

slper
New User

Jun 5, 2016, 11:58 PM

Post #25 of 25 (1870 views)
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Re: [jts1957] LG LCD no screen question [In reply to]	Can't Post

Thanks for all your help. If you are in the parts business I'd willing to purchase from you for all your time and help. If not do you recommend some place other than Shopjimmie?

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