LG M228WD TV / monitor 2 Seconds to Black.

[DemonBG]

Hope everyone is well and thank you in advance for the help.

I'm currently working on an 22” LG TV / Monitor that is presenting with the standard 2s to black symptoms. When the power on is pressed everything boots just fine – Image shows for a second and then backlight turns off and with a flashlight you can still see the image.

I started by removing all the electrolytic caps and testing them with my meter and all the capacitances were good.

I proceeded to unplugging every individual lamp and testing again (4 in total) and again, fault persists so I can either assume all the lamps are ok… or all are broken. (I am going to assume they are all good).

I have tested the Fuse and the diodes in situ and again all check ok.

Next I probed the output voltages into the signal board and all are either: 15V, 5V or 3.3V as specified on the markings so that seems ok which makes me think that power board is ok and the problem lies with the inverter section of the board?

Lastly I probed the two inverter transformers on the secondary side and again, both show about 1.1K

Now after that I am fairly stumped as to what the problem could be – If there is absolutely anything you would suggest I would greatly appreciate it.

Warm Regards,
Demon

(P.S - Those are pen marks, not burn marks on the transistors on the underside)

[selldoor]

Re: LG M228WD TV / monitor 2 Seconds to Black.

I proceeded to unplugging every individual lamp and testing again (4 in total) and again, fault persists so I can either assume all the lamps are ok… or all are broken. (I am going to assume they are all good).


Not sure what you mean here- unplugging a damaged light does not enable the other 3 to work - you have to have all four working for them to stay on.

Can you also state exactly what the secondary winding resistances are .

Did you read this guide by retiredcaps -if not start at post19.
https://www.badcaps.net/forum/showthread.php?t=10419

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

[DemonBG]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Hi Selldoor,

Thank you for the reply - One of the transformers is giving 1.105K on the secondary and the other is 1.123K.

I did not realise all 4 need to be active so i will take a closer look at the lamps (or will see if i can find a spare lamp so i dont need to take the LCD apart)

I must admit i only read the first post - Was part way through the rest when i posted so will carry on with that.


Would you like me to retake any of the images?

Warm Regards,
Demon

[selldoor]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Perhaps another of the top of the board the other is ok - I think the pictures came up after I had read the post or missed them completely.
Are all the 4 transistors the same can you post the part numbers. I think I can read them but couldnt spot a data sheet.

I would go for testing the lamps again -perhaps one at a time in a working screen? - transformers look good . In the 2 sec to black there is a test to see if transistors are shorted. - I am going out now for an hour or so. You will get a few more ideas when the US members come on line.

[DemonBG]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Another picture posted from top side of the board - Im afraid i cant seem to get a clear shot without flash which results in the blooming in the middle of the shot...


Anywho, the transistors are in 2 pairs, each of which consists of (Going left to right):

[62T03GH 743271] [9563GH 810276] [62T03GH 743271] [9563GH 810276]

Thank you for all the help so far,

Demon

[selldoor]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Ha! couldnt read the number that why I couldnt find them.

Data sheets attached

[DemonBG]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Hi Selldoor,

Very much appreciate the help so thank you so much. I will be honest when i say i dont really know what i am looking at in those data sheets - I had a quick look at the schematic of it and tested the diodes to the best of my ability but not really sure what i am doing... Any guidance would be appreciated.


All the best,
Demon

[sabre504]

Re: LG M228WD TV / monitor 2 Seconds to Black.

I have found that a lot of the 22" units i have dealt with in the past have had the top 2 ccfl's with wiring issue.

The earth wire tends to go brittle at the solder joint so worth checking before you go too far testing and replacing parts .

I am lucky in the respect that i have a couple of old cracked screens i keep for testing so i dont have to strip the screens unless i need to but you may have too unless you can lay your hand on a couple of lamps .

[DemonBG]

Re: LG M228WD TV / monitor 2 Seconds to Black.

You guys are absolute geniuses! dug out a old broken LCD panel and plugged it in to the very top port and Bingo! Boots up perfectly! The interesting thing is, now i can actually hear something "sizzle" when that backlight (broken one) at the top tries to boot... Would that suggest it is broken?

Thanks again all,
Demon

[selldoor]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Too many "Broken" parts - you need to be specific do you mean the part that was originally in the set or the part from the Broken set that works.
Whichever, the sizzle is likely to be from damaged wiring or solder joint at the bulb - this can be cleaned and repaired. If you have it in pieces when you are testing and you can darken the room, you can sometimes see arcing
to accompany the sizzle.

[DemonBG]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Sorry about that - I meant to say that there is a failed backlight in the TV and i used a working bulb from another, different panel to verify.

The failed backlight in the TV makes a noise - As it happens, the Bulb itself is ok but the wire leading to the bulb has broken off and the noise I heard was arcing.

Im curently in the middle of re-soldering the wire, will re-post images as soon as im done.

Regards,
Demon

[DemonBG]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Job Done!

Wire re-soldered (needed a little bit of an extension) but all reassembled and working so far

Thank you all so much for the help, i cannot tell you how much i appreciate it!

Warm Regards,
Demon

[selldoor]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Well done! - another one saved from the tip.

[sabre504]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Good job

[gambitt007]

Re: LG M228WD TV / monitor 2 Seconds to Black.

nicely done.

[beachch]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Hey Demon, I'm having the EXACT same issue on the same monitor. Do you have an email I could reach you at for a few questions? Thanks!

[Wrog]

Re: LG M228WD TV / monitor 2 Seconds to Black.

@DemonBG: Excellent work, congrats!!

@Beach: Consider posting your questions to the forum (even if it is after you've received your answers). Chances are, eventually someone else will run into the thread and will have the same questions! Thanks.

[DemonBG]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Heyhey Beach,

Feel free to drop me a PM and I will help however I can, at the same time you are more than welcome to take over this thread and carry it on - I myself am but an ape compared to some of the geniuses here but will of course do what little I can!

Good luck,
Demon

[beachch]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Alright, so it's the same monitor as yours and I was having the same problem. I'd turn it on and then after 1-2sec it'd shut off but if I shine a flashlight on the screen I could still see the picture.

I did some research and found this thread and finally got everything disassembled. I was checking the wires on the backlights and it looks like the exact same wire you took a picture of was loose and just hanging there.I got it soldered back on and tested them all before I put that LCD screen back together (those things are a bitch).

Connected everything back together and plugged it in and same problem still happens, but it seems that if I unplug the LCD screen from the boards (the smaller red and white ribbon-type cable) and test it then the backlights turn on and work fine. Leads me to believe something on the board where the signal is going to the LCD is messed up.

Any help/suggestions are appreciated! Thanks!

[selldoor]

Re: LG M228WD TV / monitor 2 Seconds to Black.

Remove the ribbon and check it for damage clean and replace.
( If its reverable make sure its the right way round at each end)


Please post pictures of your main 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 a bit about yourself - skills tools etc.