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I have a LG 55LW4500 I already replaced the mainboard, but

Customer Question
Hi JA: Hello. How can we...
Hi
JA: Hello. How can we be of help?
Customer: I have a LG 55LW4500 I already replaced the mainboard, but there is no image (only sound of input), and backlight is ok.
JA: Has this happened before? And have you tried unplugging your LG and leaving it off for a few hours?
Customer: Do I need to replace the Power Supply board ? Oh yes, it is unplugged for weeks now
JA: Does the TV menu work? Do you have the same problem on all sources/inputs?
Customer: No TV menu
JA: How long has this been an issue? What happened right before this popped up?
Customer: This is an old issue, happened suddently I have to try the SMPS test I am reading on your website
JA: Is there anything else the TV Technician should be aware of?
Customer: Do you provide diagram please ? But I'm not sure you will help me
Submitted: 6 months ago.Category: TV
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Answered in 5 minutes by:
5/11/2017
TV Technician: Anthony_Infotech, Technician replied 6 months ago
Anthony_Infotech
Anthony_Infotech, Technician
Category: TV
Satisfied Customers: 15,162
Experience: 20+ years experience TV expert (field and bench) 9 approved qualifications in TV-ELECTRONICS
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Hello
Welcome
I am sorry you are having trouble here,I am presently reviewing your question be with you very soon.

Anthony

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Customer reply replied 6 months ago
Hi Anthony, thank you.
Customer reply replied 6 months ago
Hi Anthony, thank you. I'm French but I'm able to understand.
TV Technician: Anthony_Infotech, Technician replied 6 months ago

If the back-lights are lit no pic just sound then the t-con board is bad, this board drives the LCD panel (screen)

what you need to do is get the back off the set, now you will see a unmistakable ribbon or multi-strand lead going from the main-board (that's the one with all the AV input connectors on)to the t-con usually mounted upper middle of the set and may be covered by a metal shield, you need to carefully get this board out of the set (its about 5 inches by 2 half)and retrieve the part-number found on the board itself with this part-number go to www.shopjimmy.com first if they don't have it google the part-number for suppliers

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Customer reply replied 6 months ago
Shop Jimmy is not accessible form France for now, I already ask him.
TV Technician: Anthony_Infotech, Technician replied 6 months ago

You will need to google the part-number for the t-con board found on the board itself

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Customer reply replied 6 months ago
I bought a replacement board from LG already and the issue is the same. The only thing I noticed is about P201 connector, last 24V is missing.
TV Technician: Anthony_Infotech, Technician replied 6 months ago

NO you replaced the main-board the one with all the AV inputs on?the t-con is a DIFFERENT board

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Customer reply replied 6 months ago
not the Power Supply board, the Main board with all the AV inputs, what you call T-con.
TV Technician: Anthony_Infotech, Technician replied 6 months ago

Can you send me a picture of the inside of the set please?you can use an upload tool your end it may be a paperclip, I will then point out the t-con to you

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TV Technician: Anthony_Infotech, Technician replied 6 months ago

I don’t know why you took out power-board please put back in thanks

https://snag.gy/pDRTCo.jpg

Click on the above t-con board is under that piece of metal shielding

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Customer reply replied 6 months ago
Oh, there is a third board ? I was looking for cold joint and damaged components on the PS board.
TV Technician: Anthony_Infotech, Technician replied 6 months ago

Yes that is the problem board

Please could you rate the answer positively with the rating bar of stars at the top of the page, rating me positively enables me to receive payment from the site thank you, ***** ***** question is open for 30 days

Many Thanks

Anthony

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Customer reply replied 6 months ago
Oh already found ? Is it a replaceable part ?
Customer reply replied 6 months ago
is there a way to test it by shunting something on the board for example ?
TV Technician: Anthony_Infotech, Technician replied 6 months ago

Yes but you need to use the part-number only found on the board itself, there will be two leads going from the t-con into the panel itself they can be a bit tricky to undo if you have problems take a photo

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TV Technician: Anthony_Infotech, Technician replied 6 months ago

No way to test this board at any level

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Customer reply replied 6 months ago
Ok great, thank you, ***** ***** my noobness ;)
TV Technician: Anthony_Infotech, Technician replied 6 months ago

Lol no probs order that board set will be good

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TV Technician: Anthony_Infotech, Technician replied 6 months ago

Please remember the rating before you go thanks

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Customer reply replied 6 months ago
Board is LG V6 55 FHD 120HZ 6870C-0369C_ver0.2.
I will come back to tell you ;)
TV Technician: Anthony_Infotech, Technician replied 6 months ago

ok

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TV Technician: Anthony_Infotech, Technician replied 6 months ago

How is this working out please?

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Customer reply replied 6 months ago
Hello, I will receive my new T-con board next week, maybe at Wednesday. Then I will rate you, don't worries about that. How can I do it now ? My rating will as better as your answer was correct (or not). Stop asking
TV Technician: Anthony_Infotech, Technician replied 6 months ago

Many people do not come back to do either so that is why we send a message , rate when ready no rush

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Customer reply replied 6 months ago
Hi, so I received two T-con boards.
No result, same issue.
Is the LCD panel dead ?
Thanks
TV Technician: Anthony_Infotech, Technician replied 6 months ago

I do hope part-numbers are exactly the same, if so and you are sure the backlights are lit then you are dreadfully unlucky and yes the panel is bad

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Customer reply replied 6 months ago
Unfortunately the parts are stricly identical.
Backlight is ok, main board is ok, power supply one maybe (only POWER_ON is 0V instead of 24V).
TV Technician: Anthony_Infotech, Technician replied 6 months ago

Power_on 24vdc seems way too high where did you get that info?the power_on is just that power on which you have, are you sure the 24vdc is not something else?

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TV Technician: Anthony_Infotech, Technician replied 6 months ago

Usually power_on is 3 to 5vdc or 0

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Customer reply replied 6 months ago
Maybe I'm wrong, it's the last 24V from P201 connector. I will confirm you that tomorrow, it's about 10:00PM here.
TV Technician: Anthony_Infotech, Technician replied 6 months ago

OK its unlikely power_on is 24v let me know or take a photo of that and upload

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Customer reply replied 6 months ago
Hello, did you see the picture please ?
TV Technician: Anthony_Infotech, Technician replied 6 months ago

Yes seen thank

First of all switch the set OFF put your red lead on that P201 for the 24vdc and black lead to metal chassis, switch ON does the meter come up and die away with the 24vdc?

Next disconnect the t-con board and do the same test ,any sign of this 24vdc?

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TV Technician: Anthony_Infotech, Technician replied 6 months ago

Also please take a photo of the actual P201 plug?or isnt there one?

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TV Technician: Anthony_Infotech, Technician replied 6 months ago

LG schematics are very poor and hard to understand I do have the schematic but I never use LG because they are so bad, however I did pull it and can see a 24vrail now is there a C426 capacitor nearby?

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TV Technician: Anthony_Infotech, Technician replied 6 months ago

This voltage could be the supply for the t-con board I am not sure as yet have alook on the t-con board for any supply voltage markings

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TV Technician: Anthony_Infotech, Technician replied 6 months ago

Just to add this is highly unusual for the 24vdc to be missing if it is in 99% of cases the t-con has failed,

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TV Technician: Anthony_Infotech, Technician replied 6 months ago

Just to add this is highly unusual for the 24vdc to be missing if it is in 99% of cases the t-con has failed,

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Customer reply replied 6 months ago
C426 is on the main board, not the power supply one.
TV Technician: Anthony_Infotech, Technician replied 6 months ago

Is there 24vdc on the positive end of that capacitor on the main-board

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Customer reply replied 5 months ago
Oh sorry I didn't see your answer. I will check tomorrow
TV Technician: Anthony_Infotech, Technician replied 5 months ago

Not answers just requests for info to come up with answers thanks

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Anthony_Infotech
Anthony_Infotech, Technician
Category: TV
Satisfied Customers: 15,162
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Experience: 20+ years experience TV expert (field and bench) 9 approved qualifications in TV-ELECTRONICS

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