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#1 |
Badcaps Veteran
Join Date: Jul 2012
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![]() Hi
I could do with some advice. Ive got a 55ub850v tv which turns and stays on, with backlights and sound but no picture. The fuse on the the tcon has 11.78v on both sides. There is also voltages on I assume test points at the bottom right hand corner of the tcon. There is also voltage present on the bottom left corner which fluctuate. I have checked the (as much as I can) the components on the screen boards. They seem fine. The psu output voltages are fine. The chips on the tcon is not very warm- whilst the main chip on the main board is hot-ish. I was wondering if anyone could advise on what to check next or what they suspect is faulty? I was going to change the main board. Thanks in advance |
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#2 |
Badcaps Veteran
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![]() What do you get on the screen if you have only one ribbon cable connected one at a time between T-CON and the tab boding board?
BTW, pictures are too out of focus to see Voltage test points on that T-CON board.
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Never stop learning Basic LCD TV and Monitor troubleshooting guides. http://www.badcaps.net/forum/showthr...956#post305956 Voltage Regulator (LDO) testing: http://www.badcaps.net/forum/showthr...999#post300999 Inverter testing using old CFL: http://www.badcaps.net/forum/showthr...er+testing+cfl Tear down pictures : Hit the ">" Show Albums and stories" on the left side http://s807.photobucket.com/user/budm/library/ TV Factory reset codes listing: http://www.badcaps.net/forum/showthread.php?t=24809 Last edited by budm; 04-30-2018 at 09:45 PM.. |
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#3 |
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![]() If I remove the one ribbon or both of them the screen still remains blank - I hope the attached photo of the voltages for the test points on the tcon (bottom right hand corner).
If I remember correctly they read between 1.2v to 13.9 and were static but not 18v. There are no voltages written on the bottom left hand corner of the tcon. When I removed the two ribbon cables from the tcon the voltages read the same. Sorry really struggled to get clear focused photos Last edited by thuss; 05-01-2018 at 04:25 AM.. |
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#4 |
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![]() Bottom Left hand side of tcon
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#5 |
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![]() Check the LVDS with an oscilloscope. See if the main board puts anything out. Also check to see if the panel is getting any power.
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#6 |
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![]() no havent got a scope - the main board is getting power and then in return feeds power to the tcon hence the 11.8 v on the fuses.
Would the next step be to remove the Lvds and supply 12v to tcon fuse and connect vcc to pin 41? Last edited by thuss; 05-01-2018 at 06:00 PM.. |
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#7 |
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![]() https://www.badcaps.net/forum/attach...3&d=1525142506
https://www.badcaps.net/forum/attach...0&d=1525170610 I still cannot see much test points on that inverter board, I cannot read the P/N on the barcode sticker and the P/N as printed on the board. BTW, what brand is this 55ub850v? Last edited by budm; 05-01-2018 at 10:27 PM.. |
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#8 |
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![]() its a lg tv and please see attached photo where I tested the voltages on the tcon
The part number is also on the photo |
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#9 |
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![]() as far as I can make out the p/n 6807-0502c thats all there is on the board there is no additional stickers.
The second part number maybe 6871E - 3703M? I assumed they were test points Last edited by thuss; 05-02-2018 at 09:39 AM.. |
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#10 |
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![]() LG 6871L-3703M (6870C-0502C) T-Con Board.
There many power supplies Voltages that need to be tested. Pictures provided by shopjimmy. |
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#11 |
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![]() Thank you for that - would they range from say 1v up to a max of 24V?
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#12 | |
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![]() Quote:
Just report Voltages of all those test points, make sure to put down the name and follow by the Voltage reading. Last edited by budm; 05-02-2018 at 10:41 AM.. |
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#13 |
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![]() will do thanks
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#14 |
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![]() Had two of this model both with the issues you describe in the last couple of months both were caused by faulty main boards. In both instances a replacement main board resolved the problem.Also from what I remember the 49" board will also work with no adjustments.
Hope this helps. |
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#15 |
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![]() Hi
Sorry about the late response. The readings on the tcon were as follows v18-1.6mv v15-1.9mv v14-1.7 v12-1.6 v10-1.6 v9-13.4 v7-13.5 v5-13.5 v4-13.7 v1-13.7mv vdd- 1.74v vcourfb- 1.7 vcc18- 1.6 vglI- 18.3 VIN- 11.78v VGH - 1.5mv VDD - 0.7 VCOM2- 22mv VCOM1- 22mv VCORE- 1.5mv VGH_R- 1.4mv VGH_even- 5.8mv VGH_ ODD- 5.7mv I think its the screen but any advice would be appreciated. I changed the main board still has the same symptoms. i.e No picture (the replacement board was out of a broken 49ub850v screen tv with a display). |
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#16 |
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![]() I also swapped my main board (from 55ub850v) into the broken screen 49ub850v turns on and displays a broken picture.
I also swapped the tcon out of the broken screen 49yb850v into the 55ub850v but still no picture |
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#17 |
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![]() Guess it's possible that the tcon from the 49 isn't a match for the 55?
Last edited by nomoresonys; 05-16-2018 at 08:48 PM.. |
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#18 |
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![]() One thing to try, put the 49 tcon back in the broken screen and see if it still has the picture, a lot of times a bad panel will kill a tcon. Did you try the tcon from 55 into 49?
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#19 | |
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#20 | |
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