LG 42LC46 problem

[sienoki]

Re: LG 42LC46 problem

this is best pic at mo

heres another

[tom66]

Re: LG 42LC46 problem

I see at least one regulator on the board.

Get out your multimeter. Set it to 20VDC. Place the black probe on the metal chassis; for example, a part of the metal frame like a spare screw hole. Then, turn the TV on (and make sure the picture is good.) Measure the voltage on each pin (using the red probe) - for the middle pin, measure the tab as they are connected to each other and it's easier to measure, and report the readings. Then, wait for the picture to go bad, and measure again.

Use a loupe to read the part number and report that back.

[sienoki]

Re: LG 42LC46 problem

heres another

the regulator markings are rt9164a..15pg9fr0z

[tom66]

Re: LG 42LC46 problem

Datasheet: http://pdf1.alldatasheet.com/datashe...K/RT9164A.html

"15" indicates 1.5V output, so we should see 1.5V on one pin.

[sienoki]

Re: LG 42LC46 problem

the regulator markings are rt9164a..15pg9fr0z

the middle leg is1.49
the left 1 is 0.00
the right 1 is 3.25

[tom66]

Re: LG 42LC46 problem

the middle leg is1.49
the left 1 is 0.00
the right 1 is 3.25

That's fine. Was that during failure or normal operation?

[sienoki]

Re: LG 42LC46 problem

the middle leg is1.49
the left 1 is 0.00
the right 1 is 3.25

no change in them readings after picture gone

[sienoki]

Re: LG 42LC46 problem

no change in them readings after picture gone

them readings where when picture good..them readings didnt change when picture gone

[tom66]

Re: LG 42LC46 problem

no change in them readings after picture gone

Okay so the regulator is fine.

Next step:
- turn TV off at wall
- disconnect left ribbon connector (for left side of screen)
- turn back on you should have picture on right but not on left (left hand might be random noise, or just white or black.)
- wait 10 mins does problem occur?
- turn back off, plug left in and repeat with right.

[sienoki]

Re: LG 42LC46 problem

Okay so the regulator is fine.

Next step:
- turn TV off at wall
- disconnect left ribbon connector (for left side of screen)
- turn back on you should have picture on right but not on left (left hand might be random noise, or just white or black.)
- wait 10 mins does problem occur?
- turn back off, plug left in and repeat with right.

with left ribbon off left is white and right no picture just flickering dark grey screen vice versa

[tom66]

Re: LG 42LC46 problem

with left ribbon off left is white and right no picture just flickering dark grey screen vice versa

Strange, never seen that behaviour before, okay that means my test there won't work. (Some t-cons work with half the display, due to marginal components...)

Next test is to leave the set on with ribbons connected until problem occurs, then unplug the LVDS cable, leave T-con for 30 seconds, and plug the LVDS back in, seeing if you get a picture.

Also, do you get sound during failure?

[sienoki]

Re: LG 42LC46 problem

Strange, never seen that behaviour before, okay that means my test there won't work. (Some t-cons work with half the display, due to marginal components...)

Next test is to leave the set on with ribbons connected until problem occurs, then unplug the LVDS cable, leave T-con for 30 seconds, and plug the LVDS back in, seeing if you get a picture.

Also, do you get sound during failure?

Do you want me to do your 1st test again when the set is cold..cos i only get a good picture for 10mins from cold and when picture goes bad i would have to wait till set cooled down again to get good picture back

I did your 1st test as soon as picture went so that is probably why half of screen had no picture..there was sound during failure

[sienoki]

Re: LG 42LC46 problem

Do you want me to do your 1st test again when the set is cold..cos i only get a good picture for 10mins from cold and when picture goes bad i would have to wait till set cooled down again to get good picture back

I did your 1st test as soon as picture went so that is probably why half of screen had no picture..there was sound during failure

Just done your second test had to wait to get a good picture to start with..anyways had good picture for about 8mins pulled LVDS cable waited 30secs then plugged back in but no picture m8..sound remains

[sienoki]

Re: LG 42LC46 problem

Just done your second test had to wait to get a good picture to start with..anyways had good picture for about 8mins pulled LVDS cable waited 30secs then plugged back in but no picture m8..sound remains

I asked the lad at work today what the faults where..he said he was having screen problems going shaded then flickering..after that then the start up issues(bad caps)he never told me about the screen issue when i bought it.
Do you reckon the screen itself is on its way out.

[tom66]

Re: LG 42LC46 problem

I asked the lad at work today what the faults where..he said he was having screen problems going shaded then flickering..after that then the start up issues(bad caps)he never told me about the screen issue when i bought it.
Do you reckon the screen itself is on its way out.

The fault in the pics doesn't look like a screen fault, as the noise is random like digital noise - screen faults cause bands of failure (e.g. horizontal/vertical lines, missing parts of picture, slow updating on one half, etc...)

Can you repeat the first test after the set cools down?

Do you have an oscilloscope, or can you borrow one?

[sienoki]

Re: LG 42LC46 problem

The fault in the pics doesn't look like a screen fault, as the noise is random like digital noise - screen faults cause bands of failure (e.g. horizontal/vertical lines, missing parts of picture, slow updating on one half, etc...)

Can you repeat the first test after the set cools down?

Do you have an oscilloscope, or can you borrow one?

I dont have an oscilloscope(have you seen state of my multimeter)i dont know of any1 i could borrow off.That bloke at farnells said he was a moderator on this site but i didnt get his num or name
anways i will do 1st test again

[sienoki]

Re: LG 42LC46 problem

I dont have an oscilloscope(have you seen state of my multimeter)i dont know of any1 i could borrow off.That bloke at farnells said he was a moderator on this site but i didnt get his num or name
anways i will do 1st test again

Done 1st test again with replacement t-con just same results so i tried the original t-con board..left ribbon in place i could see some of the picture but the background was white not greyed out like the replacement?right ribbon in place it was trying for a picture but not white background..weird

I wont beable to get my hands on any advanced testing equipment so it looks like im stuck with a dead set

[sienoki]

Re: LG 42LC46 problem

Since i replaced the bulged caps the set has never been on for longer than 40mins..ive now left if for 1hr with the picture like in quote 14..had 10 cups of coffee cos im dont like getting beat..especially with 90quid in it..anyways after 1hr i turned the set off by the remote(standby)and then turned it straight back on with remote and have been watching a crappy army film with patrick swayze for over 1hr..ehh
So my question is did something on the boards?just need a good charging or something???

[bbjunkie]

Re: LG 42LC46 problem

Aren't intermittent faults so much fun?

It's doubtful the fault has been fixed. I hope it has though. However in the last week I have had 2 tv's and a car heater fan all with intermittent problems that have magically started working again.. go figure!

Jim

[sienoki]

Re: LG 42LC46 problem

The fault has not been fixed..after 10mins when the picture goes the back of the set is not warm..it only starts to get warm at about 40mins..then if i turn off and on with remote the picture great for as long as the set is on..

What other tests can be done?
Im thinking solder joints but ive got a jewelers eye and had a really good look..cant see anything obvious..when i borrow a descent camera i will post some close ups of all the boards underneath..thx