Riddled TV Repair Forum
Service Menu and Manual Schematics
 
   
 FAQFAQ   SearchSearch   RegisterRegister 
   Log inLog in 
LG M2794DP - unresponsive rectangular area    
Post new topic   Reply to topic    Riddled TV Repair Forum Index -> TV Repair
 
Author Message
szteven



Joined: 14 Jul 2015
Posts: 3

PostPosted: Tue Jul 14, 2015 5:10 am    Post subject: LG M2794DP - unresponsive rectangular area Reply with quote

Hi!

I have an LG FullHD Tv+monitor, model M2794DP. A few days ago it developed an unresponsive rectangular area on the screen, showing only a static colored pattern. Sometimes this area is almost completely cyan, sometimes is almost checkered or dotted. The other part of the lcd screen works just fine. This area grows slowly, it almost doubled its size in 5 days.

Here are some pictures:





What is interesting however, is that if I activate the TV's menu, it displays just fine over this area (hence I think the lcd itself is not damaged):





It has nothing to do with the TV signal, the very same thing happens if I connect it to my PC with a VGA cable and try to use it as a monitor.

Clearly, some circuit has failed. Could you help me to determine which one, so I can buy a replacement? I have some experience in disassembling/repairing electronic devices, I could be able to replace it myself.

Thank you!
Google

PostPost subject: Advertisement

kuhurdler



Joined: 28 Dec 2006
Posts: 2844
Location: Overland Park, KS

PostPosted: Tue Jul 14, 2015 7:10 am    Post subject: Reply with quote

Remove and reseat the connectors on the T-con.
If no changes, replace the Timing Controller (T-con).
If that doesn't fix it, it is the LCD panel or its tab-bonds and it is a goner.
szteven



Joined: 14 Jul 2015
Posts: 3

PostPosted: Tue Jul 14, 2015 9:07 am    Post subject: Reply with quote

Ok, will try what you've suggested with the T-con.

Still, out of sheer curiosity, how could you explain the fact that the faulty area displays correctly the menu items (as it can be seen in the last two pictures)? The signal for displaying the menu doesn't pass through the T-con? Is there a secondary source/circuit for displaying the TV's own menu by overlaying it on the contents?

This is why I think it's not the LCD panel or the tab-bounds. If that was the case, how could it display correctly the menu icons over the faulty area?
kuhurdler



Joined: 28 Dec 2006
Posts: 2844
Location: Overland Park, KS

PostPosted: Tue Jul 14, 2015 2:32 pm    Post subject: Reply with quote

You have a good point. I stand corrected on suggesting it being the panel. Additionally, It is unusual to see a Tcon fail only part of of the way down, and even more unusual for it to grow as you described. Is this the same for all inputs?
szteven



Joined: 14 Jul 2015
Posts: 3

PostPosted: Tue Jul 14, 2015 4:53 pm    Post subject: Reply with quote

Success! I've just disassembled the TV, located the T-con, removed the shielding, pressed gently around the ribbon connectors and this did the trick! So it was a minor contact problem.

Here is the T-con board (model LG LM270WF1-TLB1-511 6870C-0252A):



The faulty area (same for all inputs) disappeared, the TV is working as new. Very Happy

I'm still wondering how could it display the menu correctly over the faulty area. The board is connected with two cables on top and one on the bottom. It may be that one of the (upper) cables is for the contents and the other one is for displaying the menu (and everything else not received as an input, but generated by the TV itself)? I don't know which one failed, I touched all the cables and connectors.

Anyway, following your advice, I was able to fix it easily. Thanks a lot, kuhurdler!
Google

PostPost subject: Advertisement

kuhurdler



Joined: 28 Dec 2006
Posts: 2844
Location: Overland Park, KS

PostPosted: Wed Jul 15, 2015 9:32 am    Post subject: Reply with quote

Glad to hear. Thanks for posting back.
Display posts from previous:   
Post new topic   Reply to topic    Riddled TV Repair Forum Index -> TV Repair All times are GMT - 6 Hours
Page 1 of 1

 


Disclaimer: All information provided by RiddledTV is strictly for information purposes only. Please observe all warnings displayed on your electronic
devices. This information should only be used to help diagnose work, and all service should be performed by a qualified technician.
Contact Us       Privacy Policy       Copyright © 2015 RiddledTV.com       Advertise on RiddedTV.com