Backlight cuts out on LG 55LD520 55" LCD

[dick_barton]

Re: Backlight cuts out on LG 55LD520 55" LCD

Lamp tester which is a useful tool for repairers.

http://www.ebay.co.uk/itm/like/36097...7297426&crdt=0

[Nick's Tvs]

Re: Backlight cuts out on LG 55LD520 55" LCD

If your backlight turns on for a split second and then off again it is due to a bad CCFL. CCFL's going out can cause the intermittent issue you had.
Also 1 or 2 seconds to dark is classic bad CCFL. No need to test any of them, once you open up the set down to the backlight, you can power it on and you will visually either be able to notice one CCFL not turn on, or be pink.

[vinceroger69]

Re: Backlight cuts out on LG 55LD520 55" LCD

do all the invertor transformer windings test the same?

[SurrealMustard]

Inverter testing question

do all the inverter transformer windings test the same?

I don't know. What would be the best way to go about testing them?

[dskall]

Re: Backlight cuts out on LG 55LD520 55" LCD

I think your problem is in your ccfl's. May be arcing to ground or contacts on tube ends bad. I think If you open it up and examine the ccfl's you will find the problem. They also sell ccfl testers.

[vinceroger69]

Re: Backlight cuts out on LG 55LD520 55" LCD

isnt 2 seconds to black also a sign sometimes of a failed transformer? is there a part number on them so we can look uo the windings as one may of failed, in various threads it is common issue and may save stripping the panel down too.

[syaoran123]

Re: Backlight cuts out on LG 55LD520 55" LCD

Bad bga solder on the mainboard. Pretty common problem on this tv series and symptoms can vary.

A hair dryer might not be powerful enough. So you will need a dedicated heat gun and some flux for this job.

[SurrealMustard]

Transformer numbers!

isnt 2 seconds to black also a sign sometimes of a failed transformer? is there a part number on them so we can look up the windings as one may of failed, in various threads it is common issue and may save stripping the panel down too.

I think your problem is in your ccfl's. May be arcing to ground or contacts on tube ends bad. I think If you open it up and examine the ccfl's you will find the problem. They also sell ccfl testers.

I need to get back to the seller to find out if I need to pursue a replacement or return of my inverter board, so I'd like to find out if there's a way to test that first. The number on the transformers reads T51.8235.210 with E14 1048 on the second line.

If the inverters and lamps test good, we'll then move on to the mainboard.