42" LG30-UA backlight/inverter issues

[budm]

Re: 42" LG30-UA backlight/inverter issues

One thing for sure is that you do have at least one bad lamp, that should be replaced first.
That is also normal not to get the lamps fully lit if the slave inverter is not connected.

[Austin420]

Re: 42" LG30-UA backlight/inverter issues

Anyone know what size ccfl this uses?

I have measured the diameter to be 3mm but there is a 940mm & a 950mm on ccflwarehouse.com

http://www.ebay.com/itm/6-Used-worki...-/190573240995

That's a link to an ebay auction, that has ended, but the seller states that they were pulled from the same TV and the measurement was 958mm.

[tom66]

Re: 42" LG30-UA backlight/inverter issues

Did you try to plug the CCFL into a different transformer output to see if the fault is with the transformer or CCFL?

[Austin420]

Re: 42" LG30-UA backlight/inverter issues

I did indeed switch to position of two of the CCFLs and the one that appeared to be blown did not light in a different position. The other bulb, when put into the place of the not working one, lit up.

As a solution I have ordered a new CCFL from ccflwarehouse.com and a new slave inverter from shopjimmy.com

I will let you know the status after I install the new parts.

[Austin420]

Re: 42" LG30-UA backlight/inverter issues

Ohh, how the news only gets worse. After receiving the new CCFL I realized that it was too small of a diameter compared to those that were already in it. It's my fault for not using a micrometer and actually measuring. CCFLwarehouse doesn't have a 4.0 mm in the length that I need.

http://www.lcdparts.net/CCFL1.aspx

This website lists a 3.4 mm diameter CCFL that is 950 mm in length. My original purchase was a 3.0 mm x 940mm. Looks like I will be giving this website a try.

P.S. I barely touched another CCFL and it snapped looks like I will be placing an order for 2 this time.

[cadiman]

Re: 42" LG30-UA backlight/inverter issues

The worst part about these models is after you get the panel backlight corrected the mainboard will take a dump.

The good news is you can use a mainboard from 32lg30-ua and 37lg30-ua and even a 26lg30-ua. (with some soldering)

Sounds like you will have a tv working here soon!

[Austin420]

Re: 42" LG30-UA backlight/inverter issues

So today on craigslist I found a guy selling CCFLs for $5 each, much better than the $25 each I just paid for 2 shipped from California. Anyways they are a 4mm diameter, but seem to be bigger than the originals. Earlier I stated that the 3mm was too small. It seems as though the ones I ordered (3.4mm) would be the correct ones.

Anyways, the picture is below and my question is how do I remove these plastic caps without breaking the bulb. Or would it just be better to solder them in somewhere with the wires that extend? Where would I solder them/ can I use these? I don't care if they break they were $10 total and it's really just an experiment while mine are shipped.

The originals were the ones without the plastic next to those with them. It's hard to see the diameter difference but I assure you that the plastic capped are 4mm and indeed wider.

[retiredcaps]

Re: 42" LG30-UA backlight/inverter issues

Anyways, the picture is below and my question is how do I remove these plastic caps without breaking the bulb. Or would it just be better to solder them in somewhere with the wires that extend? Where would I solder them/ can I use these?

This tutorial may help?

http://www.ccflwarehouse.com/lasotu.html

[Austin420]

Re: 42" LG30-UA backlight/inverter issues

It's always one thing after another isn't it. I replaced all of the CCFLs that I broke with ones of various sizes/lengths and they all worked!

Sad news is apparently one of the TABs was disconnected from the lcd screen to the board. Anyone have the best solution as to how to fix this? Also, my GF decided to investigate for a bit while I went to the bathroom. She was attempting to replace the tab to the connectors on the board. While she did this the next set of columns (the tab next to it) went bright white then out. What does this mean? I tried pressing on the new tab that was out and nothing happened. Please help....

Thanks,
Austin

[tom66]

Re: 42" LG30-UA backlight/inverter issues

It's always one thing after another isn't it. I replaced all of the CCFLs that I broke with ones of various sizes/lengths and they all worked!

Sad news is apparently one of the TABs was disconnected from the lcd screen to the board. Anyone have the best solution as to how to fix this? Also, my GF decided to investigate for a bit while I went to the bathroom. She was attempting to replace the tab to the connectors on the board. While she did this the next set of columns (the tab next to it) went bright white then out. What does this mean? I tried pressing on the new tab that was out and nothing happened. Please help....

Thanks,
Austin

Maybe ESD damage to the other tab?

As far as I am aware it is nearly impossible to reconnect the tabs without the million-dollar equipment they use in factories to manufacture these panels.

[Austin420]

Re: 42" LG30-UA backlight/inverter issues

Well I may go under the assumption that the LCD panel is no longer usable. It happened when I took the panel apart and wasn't careful enough. Entirely my fault.

What are everyone's opinions on using this panel

http://www.ebay.com/itm/42-LCD-Panel...#ht_639wt_1396

It's a 42LC4D-UA. I don't know what all of that means but I do know this:

It's a 42" LCD
It is a UA, the same as my 42LG30-UA

[budm]

Re: 42" LG30-UA backlight/inverter issues

You need to match model number of your LCD sticker to this one on E-BAY, especially the Revision number since you will have to make sure that the T-CON and the backlight inverter boards will fit and work with this E-bay panel.

[Austin420]

Re: 42" LG30-UA backlight/inverter issues

Model# LC420WX6(SL)(A1)

[budm]

Re: 42" LG30-UA backlight/inverter issues

So your panel has the sticker with these numbers on it? LC420WX6(SL)(A1)

[cadiman]

Re: 42" LG30-UA backlight/inverter issues

If it is an au-optronic panel that would be a good start.

If it is not an au-optronics panel it will not be compatible.

That means the inverters, t-con and mainboard will be different and it won`t work.

[Austin420]

Re: 42" LG30-UA backlight/inverter issues

The above number is the number on the LCD I was looking at buying.

My model number is: T420XW01 V.B

AU optronics

[budm]

Re: 42" LG30-UA backlight/inverter issues

They are not the same, the one on Ebay is LG/PHILIPS:
You have AU Optronics, so your T-CON board and Backlights inverter will not work with LG panel. You need to search for T420XW01 V.B

[kevinm34232]

Re: 42" LG30-UA backlight/inverter issues

Looks like cadiman was dead on about this set. Have the same problem with a 42LG30-UA, backlight flashes for a second then TV shuts down.

Was just going to order a new set of inverter boards but I decided to open it up to the CCFL's. Sure enough there were 4 dark colored bulbs not lighting. I replaced them with bulbs from another panel. They all light up now but still shuts down TV.

It now appears the slave inverter is bad as the fuse is blown and some mosfets are shorted. I'll go ahead and order a new one and see what happens..

[kevinm34232]

Re: 42" LG30-UA backlight/inverter issues

The new bulbs were very a similar diameter than the old ones, and when they light up for a second they all look uniform, except that they are dimmer on the slave inverter side.

I was wondering if using different bulbs could have damaged the slave board because if I remember the fuse was not blown before and those mosfets were not showing short to ground like they are now..

[kevinm34232]

Re: 42" LG30-UA backlight/inverter issues

For everyone's future info...

Replaced 4 bad CCFL's that were dark in color and would not light at all before quick shut down, with 4 bulbs from a scrap 42" panel. Had to solder them in.

All lamps then lit up but TV still shut down in 1-2 seconds.

Replaced slave inverter board that was shorted and now all CCFL's light up and no more shut down.

Very grateful to Cadiman and this forum because I would not have chosen to open up into the CCFL's if I did not see his post..