Newbie with LG 37LH5000 (PS?) problem.

[MickyLuv]

Hello, I'm new to this forum, though I've searched for and read all the related threads I can find here.

I have a LG 37LH5000 TV Slow to start (20 minutes), then vertical bars only on display. Sometimes grey scale, sometimes color.

After 45 minutes about 1 cm horizontal band of picture at top of screen.

After 1 hr picture gradually forms from bottom up, slowly "raising" a horizontal shutter-like curtain of lines.

After 90 minutes this leaves a complete picture, with a slight horizontal flicker about 2cm down from the top.

After 2 hrs, clear solid picture no flicker.

From what I've read so far, this seems like a power supply problem, possibly requiring capacitor replacement. The job will be a first for me, though I see there are lots of tutorials available.

I've included pics in the hope of some words of advice.

Plus, do the screws that need to be removed to take off the back cover all have an arrow symbol pointing at them? There does seem to be a lot of those. Or is it just the screws around the outside edge that need to be removed?

[dick_barton]

Re: Newbie with LG 37LH5000 (PS?) problem.

Switch off set, disconnect one ribbon cable from the tcon to the panel, power up, press menu and take photo of screen and then power off and reconnect ribbon and remove second ribbon to panel and repeat as above.

Remove the ribbons carefully lifting up the connector tabs so as not to damage the ribbons or connector. Replace the ribbons carefully before pushing closed the connector tabs.

There are a lot of screws. Just remember if they are different sizes where they go. Pencil and paper is useful.

Once the back is off, clear sharp well focused photo's would also be useful.

[dskall]

Re: Newbie with LG 37LH5000 (PS?) problem.

Yes lots of screws to remove. Look for any bulging caps. Sounds like a capacitor problem.

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

Thanks Guys,
I'll get those things done and report back.

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

Switch off set, disconnect one ribbon cable from the tcon to the panel, power up, press menu and take photo of screen and then power off and reconnect ribbon and remove second ribbon to panel and repeat as above.

Remove the ribbons carefully lifting up the connector tabs so as not to damage the ribbons or connector. Replace the ribbons carefully before pushing closed the connector tabs.

There are a lot of screws. Just remember if they are different sizes where they go. Pencil and paper is useful.

Once the back is off, clear sharp well focused photo's would also be useful.

Thanks, i appreciate the detailed info about the tcon panel test and I'm psyching myself up to do that one. I need to get a stand for that because this TV has been on a wall bracket.

The attached photos show the capacitors on the power supply "looking" healthy. Maybe one has a minutely raised top but that may be wishful thinking by me.

I'm a bit disappointed not to be seeing bulging capacitors here. It might've made things a bit simpler.

I need to do some more reading on the subject. Before I go further into dismantling, I'd like to know for sure what the significance is of the picture on the display coming into a perfect state after 90 minutes and staying that way until shutdown.

I've seen that power supply board and tcon faults both produce the vertical lines on screen. But does the picture coming and staying good after a warm up period indicate more strongly one or the other possibility?

Thank you kindly,

MickyLuv

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

Yes lots of screws to remove. Look for any bulging caps. Sounds like a capacitor problem.

Thanks,
I was hoping so and it may still be so, if capacitors can be faulty without showing a bulge.
I need to look into testing them by a method other than their initial appearance.

Regards,

MickyLuv

[dskall]

Re: Newbie with LG 37LH5000 (PS?) problem.

Well fortunately or unfortunately depending on your point of view. Bad caps aren't is prevalent as they used to be. So opening a set up looking for bulging caps for a cheap easy fix is not what it used to be. The good news in your case is yours maybe heat related so heating/cooling should narrow down bad component.

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

Well fortunately or unfortunately depending on your point of view. Bad caps aren't is prevalent as they used to be. So opening a set up looking for bulging caps for a cheap easy fix is not what it used to be. The good news in your case is yours maybe heat related so heating/cooling should narrow down bad component.

Thanks for the clues,
If it's a heating/cooling problem, then currently the TV is malfunctioning when it's cold and working OK when it warms up.

I'm now trying to work out which components to swap out first as a possible solution.

Regards,

MickyLuv

[dskall]

Re: Newbie with LG 37LH5000 (PS?) problem.

Try heating power board with hair dryer to see if problem clears up.

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

Try heating power board with hair dryer to see if problem clears up.

OK thanks,
first job in the morning.

Regards,

MickyLuv

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

Try heating power board with hair dryer to see if problem clears up.

Thanks for the advice.

Tried the hairdryer heating test on the power board.
It didn't seem to have any effect in the short term.

I didn't wait the full 90 minutes for results, nor the 20 initial minutes previously needed for anything at all to show on the display, mainly because I was holding the display upright on the table without a stand or back, to do the check.

Do you think I should set things up to wait the full 90 minutes, to see if there's any reduction at all in the time it takes for an acceptable display after heating the board?

Or does the fact that the initial effect of heating the power board is no different indicate that I need to look elsewhere?

Regards,

MickyLuv

[dick_barton]

Re: Newbie with LG 37LH5000 (PS?) problem.

What are the part numbers as written on the IC's. Can you give the IC board number IC801, ICxxx (can't read it) and the dc voltage on pins 1, 2, & 3

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

Switch off set, disconnect one ribbon cable from the tcon to the panel, power up, press menu and take photo of screen and then power off and reconnect ribbon and remove second ribbon to panel and repeat as above.

Remove the ribbons carefully lifting up the connector tabs so as not to damage the ribbons or connector. Replace the ribbons carefully before pushing closed the connector tabs.

There are a lot of screws. Just remember if they are different sizes where they go. Pencil and paper is useful.

Once the back is off, clear sharp well focused photo's would also be useful.

Thank you Dick Barton for your suggestions here.
I'm trying to think my way through the process before I start.
Thinking isn't a very high speed process for me.

It takes 90 minutes to get a perfectly good display on the TV.
Do I need to wait until there is a good display before I alternately
disconnect and reconnect each t-con cable?

Would any action taken on whatever observable results occur, (after waiting 90 minutes) to alternately disconnect and reconnect the t-con cables, eventually affect the 90 minutes of time it takes to get to a good display in the first place?

Please have the patience to direct me to the right tree to bark up if I'm
missing the point here.

One of the photos from my earlier reply didn't upload with the rest, so I include it here.

Kind regards,

MickyLuv

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

What are the part numbers as written on the IC's. Can you give the IC board number IC801, ICxxx (can't read it) and the dc voltage on pins 1, 2, & 3

Thanks a lot,
I'll get onto that this afternoon.
Do I leave the board in place and power up the TV to do this measurement?

Regards,

MickyLuv

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

What are the part numbers as written on the IC's. Can you give the IC board number IC801, ICxxx (can't read it) and the dc voltage on pins 1, 2, & 3

The IC board numbers are IC801 & IC803

IC801 part number: 1190A 17-33

1C803 part number: 1190E 17-18

Both these part numbers begin with a "C" in reverse character.

I'll give the voltages as soon as I can get them measured.

[dick_barton]

Re: Newbie with LG 37LH5000 (PS?) problem.

The IC board numbers are IC801 & IC803

IC801 part number: 1190A 17-33

1C803 part number: 1190E 17-18

Both these part numbers begin with a "C" in reverse character.

I'll give the voltages as soon as I can get them measured.

They are both voltage regulators and IC801 should have 3.3V output and IC803 should have 1.8V output. You need the set switched on and out of standby.

[dick_barton]

Re: Newbie with LG 37LH5000 (PS?) problem.

Delay in starting up is often down to duff capacitors or poor soldering where a little heat expands the connection and so makes the connection. There are other reasons especially the BGA chips that all to often need reflowing.

You could check the quality of the solder joints on the boards and see if any require touching up.

[dick_barton]

Re: Newbie with LG 37LH5000 (PS?) problem.

Since you suggest it's a hot/cold problem you should be able to heat up your boards to isolate the area that needs heating to bring the set on. You can use a tube with the hair dryer to focus the hot air flow.

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

Delay in starting up is often down to duff capacitors or poor soldering where a little heat expands the connection and so makes the connection. There are other reasons especially the BGA chips that all to often need reflowing.

You could check the quality of the solder joints on the boards and see if any require touching up.

Are these checked by testing the continuity?

[MickyLuv]

Re: Newbie with LG 37LH5000 (PS?) problem.

Since you suggest it's a hot/cold problem you should be able to heat up your boards to isolate the area that needs heating to bring the set on. You can use a tube with the hair dryer to focus the hot air flow.

I thought it was a heat/cold problem to start with because it ceased to be a problem after 90 minutes of being switched on.
There may well be other reasons for the problem which aren't related to the temperature. It just seemed like the most obvious reason to my inexpert mind.