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 02-19-2020, 09:01 PM   #1
arbitarytwist
New Member
 
Join Date: Nov 2016
City & State: BC
My Country: Canada
I'm a: Knowledge Seeker
Posts: 13
Default LG 43UK6300 - Audio & Backlight, but no Video

I have a LG 43UK6300BUB that has Audo and Backlight.

I am no TV expert, but have done some troubleshooting on TV's in the past.

When i turn the TV on, i can hear audio and the backlight turns on, but there is no picture. Most of the trouble shooting videos i have seen, have a seperate main and T-Con board, but it seems like on this unit, the T-CON and Main board are the same.

I have checked the voltages on the connector from the Power Supply and i seem to be getting 13V, 3V & 2V to the Main board. I tried disconnecting one panel cables at a time and still no video on either half of the TV.

I haven't found anything obvious, but was trying to check the voltage to the display, but don't see any test ports, so would appreciate some help in troubleshooting.

This TV is about 16 months old with a manufacture date of 08/2018.

I have attached some pictures for reference.
Attached Images
File Type: jpg 20200219_182112.jpg (760.4 KB, 8 views)
File Type: jpg 20200219_182116.jpg (921.8 KB, 12 views)
File Type: jpg 20200219_182644.jpg (538.8 KB, 5 views)
File Type: jpg 20200219_182710.jpg (490.4 KB, 5 views)
File Type: jpg 20200219_182715.jpg (461.3 KB, 3 views)
File Type: jpg 20200219_182718.jpg (467.3 KB, 3 views)
File Type: jpg 20200219_182722.jpg (484.3 KB, 4 views)
arbitarytwist is offline   Reply With Quote
Old 02-20-2020, 09:34 PM   #2
arbitarytwist
New Member
 
Join Date: Nov 2016
City & State: BC
My Country: Canada
I'm a: Knowledge Seeker
Posts: 13
Default Re: LG 43UK6300 - Audio & Backlight, but no Video

OK did some more looking around and seems like a burnt Transistor. I wasn't that pronounced, as in the original pics i posted, but i figured i try the oven bake and it made it more obvious. The behavior is the same as before the bake in.

I have attached some closeup pics (before over bake as seen in Pic #2 in original post).

How would i go about finding what the transistor and perhaps replace it. The two resistors above it when measured are around 70 Ohm each although there is some discoloration on one of them perhaps from the burnt transistor.

The part # for this mother board is EBU64688103 and wondering if i use EBU64688102, will that work, or would that be a different firmware ?

The complete model # for this TV is 43UK6300BUB.
Attached Images
File Type: jpg Zoom1.jpg (466.1 KB, 24 views)
File Type: jpg Zoom2.jpg (95.6 KB, 19 views)

Last edited by arbitarytwist; 02-20-2020 at 10:13 PM..
arbitarytwist is offline   Reply With Quote
Old 02-21-2020, 01:31 AM   #3
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: 38,506
Default Re: LG 43UK6300 - Audio & Backlight, but no Video

I would remove that Transistor and then check the resistance between Ground against all 3 empty pads of that Transistor to see if any one of them shows <50 Ohms.
If not then put the cables between the main board and the LCD panel back in place and recheck the resistance again to see what it shows on all 3 pads.
We want to make it is not short circuit in the LCD panel that causes the Transistor to burnt out.
__________________
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
budm is offline   Reply With Quote
Old 02-21-2020, 09:31 AM   #4
arbitarytwist
New Member
 
Join Date: Nov 2016
City & State: BC
My Country: Canada
I'm a: Knowledge Seeker
Posts: 13
Default Re: LG 43UK6300 - Audio & Backlight, but no Video

Quote:
Originally Posted by budm View Post
I would remove that Transistor and then check the resistance between Ground against all 3 empty pads of that Transistor to see if any one of them shows <50 Ohms.
If not then put the cables between the main board and the LCD panel back in place and recheck the resistance again to see what it shows on all 3 pads.
We want to make it is not short circuit in the LCD panel that causes the Transistor to burnt out.
So i took some measurements with panel cables disconnected to ground and am getting 30 KOhm, 50 KOhm and 80 Ohms on the emitter (leg by the R1104). With the panel cables hooked up, there isn't much change.
arbitarytwist is offline   Reply With Quote
Old 02-22-2020, 10:53 AM   #5
arbitarytwist
New Member
 
Join Date: Nov 2016
City & State: BC
My Country: Canada
I'm a: Knowledge Seeker
Posts: 13
Default Re: LG 43UK6300 - Audio & Backlight, but no Video

Quote:
Originally Posted by budm View Post
I would remove that Transistor and then check the resistance between Ground against all 3 empty pads of that Transistor to see if any one of them shows <50 Ohms.
If not then put the cables between the main board and the LCD panel back in place and recheck the resistance again to see what it shows on all 3 pads.
We want to make it is not short circuit in the LCD panel that causes the Transistor to burnt out.
With the postage values do you concur there is no short ? How would I go about finding a replacement transistor. Can't find any part# on the old one.

Is there anything else I could do to be 100% sure it's not the panel.
arbitarytwist is offline   Reply With Quote
Old 02-25-2020, 11:01 PM   #6
arbitarytwist
New Member
 
Join Date: Nov 2016
City & State: BC
My Country: Canada
I'm a: Knowledge Seeker
Posts: 13
Default Re: LG 43UK6300 - Audio & Backlight, but no Video

So i did a bit more digging and following are the voltage readings i got

OFF (V) ON (V)
B 7.8V 10.5V
E 7.8V 13 V
C 0V 0V (No Transistor in Place)

This makes me think its a PNP transistor. I am wondering what i can use as a transistor to make this work.
arbitarytwist is offline   Reply With Quote
Old 02-27-2020, 02:36 PM   #7
sintv
Member
 
Join Date: Feb 2015
City & State: cowdenbeath
My Country: scotland
I'm a: Knowledge Seeker
Posts: 24
Default Re: LG 43UK6300 - Audio & Backlight, but no Video

Disconnect one of the screen cables and see what happens. Iv just scrapped a slightly older LG although it had a Tcon board. Symptom was no video but backlights and sound ok. When I removed one cable, picture came on half the screen.
sintv is offline   Reply With Quote
Old 02-27-2020, 08:53 PM   #8
arbitarytwist
New Member
 
Join Date: Nov 2016
City & State: BC
My Country: Canada
I'm a: Knowledge Seeker
Posts: 13
Default Re: LG 43UK6300 - Audio & Backlight, but no Video

Quote:
Originally Posted by sintv View Post
Disconnect one of the screen cables and see what happens. Iv just scrapped a slightly older LG although it had a Tcon board. Symptom was no video but backlights and sound ok. When I removed one cable, picture came on half the screen.
I tried that already. Makes no difference.
arbitarytwist 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 - 2020
Powered by vBulletin ®
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 11:38 PM.
Did you find this forum helpful?