42lg3000-za No Picture but got sound

[Jahson]

Re: 42lg3000-za No Picture but got sound

Cheers Budm yea i have come across a similar repair kit. Im not at the set, will be there on monday. I cant remember if i did check those 3 points.

[Jahson]

Re: 42lg3000-za No Picture but got sound

yesday i was doing some probing on the mainboard, & i came across a zener diode that was reading .000, i double check.

ZD503 is the one giving me this reading ive circled it in blue.

The zener diode was still on the board when i took the reading.

[Jahson]

Re: 42lg3000-za No Picture but got sound

Yesday i was doing some probing on the mainboard, & i came across a zener diode that was reading .000, i double check.

ZD503 is the one giving me this reading ive circled it in blue.

The zener diode was still on the board when i took the reading.

[tom66]

Re: 42lg3000-za No Picture but got sound

Check on ohms too. Do you have a picture of the underside of the board where the diode came from?

[Jahson]

Re: 42lg3000-za No Picture but got sound

Okay just check it on 200ohms it reads 01.0 in both directions.

[Jahson]

Re: 42lg3000-za No Picture but got sound

Got hold of a next 42LG3000-ZA tried the inverter boards, no joy also tried the AV board no joy, changed the mainboard no joy?

The T-Con was different so could not change it.

Whots the chances its the T-con the problem?

[selldoor]

Re: 42lg3000-za No Picture but got sound

Hi - is this another non-working set?
By the way I have been looking back and still cannot see that we sorted out testing the
inverter transformers. Perhaps you can do comparison tests with the second lot.
Try and do all the pins - like 1 to 1 1to2..........1 to12 then 2 to3 ......2 to12 and so on.
Just record those in the 300 -2000 range. Tomorrow if I remember I will try and hunt down those transformers -

[tom66]

Re: 42lg3000-za No Picture but got sound

What was the panel in the other TV? The problem could still be in the main board, because the other main board may be configured for the wrong panel, causing no display.

[Jahson]

Re: 42lg3000-za No Picture but got sound

The other set had a broken screen, tell the truth i was in a hurry an changed the inverters, av board, mainboard. This was like 12am

The mainboard and av board part numbers are the same.

The inverters had a different model number ended .50 (not at set cant remember full details) mines ended 54 & 55.

So i was going try test again but with my old inverters back in set.


I thought it be a good idea to buy the smashed set, so i could test an see if things are the same.

I try get the T-Con part numbers later when my friend gets back, The T-con from the smash set was twiced the size of my original T-con.

[Jahson]

Re: 42lg3000-za No Picture but got sound

I put back the original inverters still no joy, with the replacement mainboard.

I notice iT gives 3 red pulsing flashes before it switches to the blue colour to say its on? if thats any help.

original inverters master = vit71053.54 logah rev:0
original slave = vit71053.55 logah rev:0

Replacement master = vit71053.50 logah rev:3
Replacement slave = vit71053.51 logah rev:3

Original T-con p/n - T370XW02 VC CTRL BD
Replacement T-con p/n - T420XW01 CTRL BD

[Jahson]

Re: 42lg3000-za No Picture but got sound

Try and do all the pins - like 1 to 1 1to2..........1 to12 then 2 to3 ......2 to12 and so on.
Just record those in the 300 -2000 range. Tomorrow if I remember I will try and hunt down those transformers -

It seems confusing in preview mode? didnt write it like that. Everything to the far right is T2.

Also stated when (meter set to 2k)

Meter set to 200 ohms

Master Inverter Test
Transformer T1 Transformer T2

1-2 = 00.6 same
1-3 = 00.6 same
1-4 = 00.6 same
1-5 = 00.6 same
1-6 = 00.6 same
1-7 = .519 (meter set 2k) .521
1-8 = .519 (meter set 2k) .521
1-9 = .536 (meter set 2k) 1 left side all settings
1-10= .536 (meter set 2k) 1 left side all settings
1-11= .536 (meter set 2k) .539
1-12= .519 (meter set 2k) .539

2-3 = 00.6 same
2-4 = 00.6 same
2-5 = 00.6 same
2-6 = 00.6 same
2-7 = .518 (meter set 2k) .522
2-8 = .518 (meter set 2k) .522
2-9 = .536 (meter set 2k) 1 left side all settings
2-10=.536 (meter set 2k) 1 left side all settings
2-11=.536 (meter set 2k) .540
2-12=.536 (meter set 2k) .540

3-4= 00.6 same
3-5= 00.6 same
3-6= 00.6 same
3-7= .519 (meter set 2k) .522
3-8= .519 (meter set 2k) .522
3-9= .537 (meter set 2k) 1 left side all settings
3-10=.537 (meter set 2k) 1 left side all settings
3-11=.537 (meter set 2k) .540
3-12=.537 (meter set 2k) .540

4-5= 00.7 same
4-6= 00.7 same
4-7=.519 (meter set 2k) .523
4-8=.519 (meter set 2k) .523
4-9=.537 (meter set 2k) 1 on left side all settings
4-10=.537 (meter set 2k) 1 on left side all settings
4-11=.537 (meter set 2k) .539
4-12=.537 (meter set 2k) .539

5-6= 00.7 same
5-7=.520 (meter set 2k) .522
5-8=.520 (meter set 2k) .522
5-9=.538 (meter set 2k) 1 on left side all settings
5-10=.538 (meter set 2k) 1 on left side all settings
5-11=.538 (meter set 2k) .540
5-12=.538 (meter set 2k) .540

6-7=.520 (meter set 2k) .522
6-8=.520 (meter set 2k) .522
6-9=.538 (meter set 2k) 1 on left side all settings
6-10=.538 (meter set 2k) 1 on left side all settings
6-11=.538 (meter set 2k) .540
6-12=.538 (meter set 2k) .540

7-8=00.7 same
7-9=15.4 1 on left side all settings
7-10=15.4 1 on left side all settings
7-11=15.4 15.2
7-12=15.4 15.2

8-9=15.4 1 on left side all settings
8-10=15.4 1 on left side all settings
8-11=15.4 15.2
8-12=15.4 15.2

9-10=00.6 same
9-11=00.6 1 on left side all settings
9-12=00.6 1 on left side all settings

10-11=00.6 1 on left side all settings
10-12=00.6 1 on left side all settings

11-12=00.6 same


Same=T2 same as T1, also i did try separate the readings,
Now i go do the slave transformer.

[Jahson]

Re: 42lg3000-za No Picture but got sound

Did someone find the fix, how do i test the ccfl's

[cadiman]

Re: 42lg3000-za No Picture but got sound

I was able to tell just by looking at them. You will see burn marks on the inside.

There are a few types pending panel maker. The ones you have should clip in. I prefer soldered myself. Thats what I do when replacing them.

I always have panels around so I just use what I have from other 42" panels.

The main issue with different models is the lcd panel including the t-con needs to stay with that mainboard. The backlight may be similar and the power supply will normally be the same with these since all inverters run on 24v and use the same control system for the most part. You just need to remember the lcd display, t-con and mainboard must stay together as far as L/G 42lg20.30.50 You can swap the mainboards only within the model families like all 26,32,37,42,lg 30-ua models can use the same mainboard The 26 will need a modified plug (it is missing from the larger models) but the board pinout is still there.

[fantoma]

Re: 42lg3000-za No Picture but got sound

Did you repair that lcd?
Maibe i can help you.
i just fix a master inverte board for 42lg3000 lcd.

[fantoma]

Re: 42lg3000-za No Picture but got sound

Assemble all parts together.
Plug in all connectors.
Power on the lcd. Whith your multimeter set on DC , check between pins 1,2,3,4 or 5, and 6,7,8,9 or 10 ,on master inverter power plug CN1, if there is 24Vdc, if so, check between pins 6,7,8,9 or 10 and pin 12, if there apear 5Vdc on pin 12 when you power up your lcd, and dissapears when you power down yor lcd from remote control. If all are ok, there is an defective master inverter board.
Now, on the master inverter board find U1, located betwen connectors CN1 and CN2, this in an 5Vdc regulator (78M05), on pin 1 you must find 24Vdc , on pin 3 5Vdc, pin 2 is chassis and is grounded.
If you don't have 24Vdc on pin 1, check fuse. The fuse is F1, located near pin 1 of CN1 power connector, is black an marked 2.0 . Unplug LCD from mains, replace fuse F1 (short it just for test), and you got a fully working LCD.
Please post here your results to see if this helped you.
Best regards...

[Alessio]

Re: 42lg3000-za No Picture but got sound

Assemble all parts together.
Plug in all connectors.
Power on the lcd. Whith your multimeter set on DC , check between pins 1,2,3,4 or 5, and 6,7,8,9 or 10 ,on master inverter power plug CN1, if there is 24Vdc, if so, check between pins 6,7,8,9 or 10 and pin 12, if there apear 5Vdc on pin 12 when you power up your lcd, and dissapears when you power down yor lcd from remote control. If all are ok, there is an defective master inverter board.
Now, on the master inverter board find U1, located betwen connectors CN1 and CN2, this in an 5Vdc regulator (78M05), on pin 1 you must find 24Vdc , on pin 3 5Vdc, pin 2 is chassis and is grounded.
If you don't have 24Vdc on pin 1, check fuse. The fuse is F1, located near pin 1 of CN1 power connector, is black an marked 2.0 . Unplug LCD from mains, replace fuse F1 (short it just for test), and you got a fully working LCD.
Please post here your results to see if this helped you.
Best regards...

Hello
I have 7vdc on Pin 3
22,5Vdc on Pin 1

Help?

[Alessio]

Re: 42lg3000-za No Picture but got sound

Hello,
F1 > 24v
F2 > 0v




How to replace F2?

KOAC 8A FUSE

[cosmindaniel]

Re: 42lg3000-za No Picture but got sound

So, yesterday i was to LG service. I have a 42LG3000 television, with this simptoms white screen but good sound. Actually i try to change T-con Module, i bought a new one, i replace all condensators, finally from service sad me this: YOUR DISPLAY IS DEAD, ACTUALLY , the matrix from this is broken, its necessary to buy a new one, but may be you need to buy a new tv.
So if you have this problem, don't try to change some parts from inside, because 99% the display is broken............
Good Luck.

[majterix]

Re: 42lg3000-za No Picture but got sound

hello my friends...i have the same tv 42LG3000 i have the this same problem. first i try to open the tv and i was in three times flash the power led that seems to try to open and then close..i check the volt from power suply and it is ok . for the inverters 24 volt 5 volt and 3,3 volt . next i check one by one the inverters and i find that the one of this doesnt work the half transistor caled nikos .......... i try and put off only the inverters and try to open the tv... now i have only sound. this is good .. for one reason.but i need to power on the screen. i bought from internet the same inverters..i put them and now do this... open normaly with sound. but give me only one secont of view.. then black screen again with sound.. i have check the screen with bright lamp and i can see something but i need to work the backlight. can you help me what i have to check?? i repeat that now open normaly with backlight but only one secont then black screen again but i have sound.

[dick_barton]

Re: 42lg3000-za No Picture but got sound

Can you give the name and voltages on the two connectors shown.

Photo courtesy of Shopjimmy