Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting TVs and Video Sources
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 12-26-2014, 12:52 AM   #1
Dangermoose007
Member
 
Join Date: Sep 2013
City & State: Lubbock, Texas
My Country: US
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 31
Default LC-26DV24u White Screen - Sound Ok

So I have a TV in my bedroom which I was given as a repair job due to a white screen issue. I suspected the T-Con board, but could never get it to replicate the issue after months of use. I gave it back thinking it must be something wrong with his input device, but he kept experiencing the issue so he gave it to me as a freebie. Its been sitting for months in the bedroom unused, until I got a chromecast today and figured I'd start being lazy and watch TV in bed.

Of course, since I decided to use it for personal enjoyment, lo and behold, white screen. Sound works fine, this TV has a built in dvd player and I can hear it going, but all I get is a very bright white screen. Google being my friend I was directed to look into the mainboard to t-con ribbon cable (which I can't seem to re-seat for the life of me) and power supply transistor Q413 and fuse F404. I have attached the readings I get from both in an image, as well as the ribbon cable. It seems to me the voltage on the middle connection of the transistor (I believe is the collector) is far too high, as other posts I read on this issue show readings closer to 1.5V

As an aside, when I was checking q413, I believe I shorted a connection somewhere and the TV started working again, until I move my meter probe off what it was touching, and it immediately cut back out. I have not however been able to replicate what I did which made the picture cut back in, as I was watching the screen, and did not see exactly what my probe was touching.

I'm still a noob as all of my previous repairs have involved replacing bad caps, or entire main boards/power supply boards. So individual component level details I have no experience with. How does the voltage look, or any other suggestions?
Attached Images
File Type: jpg Voltage Readings.jpg (645.3 KB, 11 views)
File Type: jpg white screen.jpg (224.2 KB, 11 views)
File Type: jpg psboard.jpg (940.7 KB, 10 views)
File Type: jpg Main to t-con ribbon.jpg (693.3 KB, 13 views)
Dangermoose007 is offline   Reply With Quote
Old 12-26-2014, 01:23 AM   #2
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 39,206
Default Re: LC-26DV24u White Screen - Sound Ok

That is the commonly failed transistor which supplies the Voltage to run the T-CON board.
http://s807.photobucket.com/user/bud...?sort=3&page=1

You can check for cold solder joints on all 3 legs of that transistor.
__________________
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; 12-26-2014 at 01:25 AM..
budm is offline   Reply With Quote
Old 12-26-2014, 07:42 PM   #3
Dangermoose007
Member
 
Join Date: Sep 2013
City & State: Lubbock, Texas
My Country: US
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 31
Default Re: LC-26DV24u White Screen - Sound Ok

Well holy smokes, that seems like that was it. I checked the solder joints and didn't see anything that looked like a cold solder to me, but I sucked the solder away and flowed new solder in its place anyways, and now it's working.

Thanks Budm!
Dangermoose007 is offline   Reply With Quote
Old 12-28-2014, 12:03 AM   #4
Dangermoose007
Member
 
Join Date: Sep 2013
City & State: Lubbock, Texas
My Country: US
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 31
Default Re: LC-26DV24u White Screen - Sound Ok

Never mind, its back to white screen tonight.
next idea?
Dangermoose007 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2022
Powered by vBulletin ®
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 12:19 PM.
Did you find this forum helpful?