LG L1952TQ: White screen, lights on but no image

[CapBlown]

Got this 19" monitor from a friend. The picture is missing while CCFL's are working as the light comes straight through. No build in menus or picture can be seen.

Visual inspection revealed no heated spots, no bulging caps nor any other defective looking parts. All seems good, though caps are some "con" caps.
I've checked both voltages on logic board are ok. (12.1 V and 5.0 V)

I did read from another threads that this kind of problem may be caused by blown fuse on logic board or the panel board. I can't locate any fuses on either. Measured some lookalikes on panel board but they seemed to be resistors.

Any ideas please.

[lucky13]

Re: LG L1952TQ: White screen, lights on but no image

White screen is usually panel problem if the cable between the logic board & LCD is in securely (especially if you have not even touched it yet).

There are fuses on the LCD board (integrated T-con so to speak). If the fuses on it are OK, then the panel is defective.

What I do is then scrap the lights for testing other inverters. I also keep the whole assembly of P/S with Logic board to test other CCFLS (connect VGA & power) and you can turn on/off CCFLs at will. makes troubleshooting quicker as you have good lights & good inverter.

[CapBlown]

Re: LG L1952TQ: White screen, lights on but no image

There are fuses on the LCD board (integrated T-con so to speak). If the fuses on it are OK, then the panel is defective.

Thanks. Located the 2A fuse on LCD panel board, it's blown. I better get some of those. Is there something typical defects to check for before replacing it with new one?

[jetadm123]

Re: LG L1952TQ: White screen, lights on but no image

Hello! Since there is a possible short somewhere in the panel and for testing purposes, consider temporarily soldering a glass type cartridge fuse holder across the pads of the old fuse (after of course, you've taken the old fuse out). You can use thin gauge wire from a old telephone or cat5 cable to connect the fuse holder to the circuit board. DO NOT bend the wires after soldering them to the circuit board, otherwise you'll lift the copper pad off the the board. Replacing glass type fuses will probably be much cheaper than replacing smd fuses. Once you figure out the problem, you can replace the above contraption with the proper smd fuse.

I have a similar "white screen" problem with a Hannstar display panel. It too, had a blown fuse. Found a shorted diode, replaced it, but still no picture.

[CapBlown]

Re: LG L1952TQ: White screen, lights on but no image

What are these "AR13 and AR11" parts? Could they be 4 parallel resistors in one chip?

MMC gives 100 ohms when measuring opposite sides. One chip has 2 of opposite sides shorted.

[Wrog]

Re: LG L1952TQ: White screen, lights on but no image

Resistor arrays (also called resistor networks). They come in many different flavors, where they could be independent (straight through opposite sides) or tied together (have a common pin, sometimes marked with a dot).

[CapBlown]

Re: LG L1952TQ: White screen, lights on but no image

Thank you Wrog.

I did some googling with array resistors and I guess that this is it 741X083 so I would have 2 of them to replace... but there is something like 0.3 mm to solder each pin in place. Looks pretty much impossible to me. Width of the array is only 1 mm.

[retiredcaps]

Re: LG L1952TQ: White screen, lights on but no image

but there is something like 0.3 mm to solder each pin in place. Looks pretty much impossible to me. Width of the array is only 1 mm.

I like the CuriousInventor soldering videos...

http://www.youtube.com/watch?v=3NN7UGWYmBY

Make also posted something similar just yesterday

http://www.youtube.com/watch?v=ihoX7x0RBz8

[CapBlown]

Re: LG L1952TQ: White screen, lights on but no image

I like the CuriousInventor soldering videos...

http://www.youtube.com/watch?v=3NN7UGWYmBY

Make also posted something similar just yesterday

http://www.youtube.com/watch?v=ihoX7x0RBz8

That was amazing...

Thanks retiredcaps, I might even try it someday though I need to get new soldering tip and that magic stuff in the bottle.

[jetadm123]

Re: LG L1952TQ: White screen, lights on but no image

Capblown, please keep us informed on your progress. I haven't seen a whole lot of success stories for "white screen" repairs when it concerns the LCD panel circuit board. There's very little info on the internet concerning these circuit boards. And what a pain trying to read/identify some of the components on these boards!

[alexanna]

Re: LG L1952TQ: White screen, lights on but no image

I have found two white screen problems related to the 30 pin ribon cable.They ohm tested good,But changing the cable has solved the problem.so if you have similar cable it might be worth a try
Al.

[emta41]

Re: LG L1952TQ: White screen, lights on but no image

I have the same problem with LG W2241S. Logic board is ok, cable is ok. But I cant find any fuse on panel board. Do you have any experience with?

[selldoor]

Re: LG L1952TQ: White screen, lights on but no image

Logic board is ok, cable is ok.

How do you know that?

Welcome to the forum-
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
https://www.badcaps.net/forum/attach...1&d=1290283049

https://www.badcaps.net/forum/attach...7&d=1280167246

It will be useful if you can say what the supposed fault was and a bit about yourself - skills tools etc.