LG 43UF640V half picture

[Davi.p]

Re: LG 43UF640V half picture

On the panel's board: resistors can be tested without current in, in ohm test, capacitors tested in volt with current in, usually there are only 2-3 voltages, 15v, 6v, 3,3v , if a cap have no tension then is shorted. The behaviour of the boards in freezer is strange, does them makes the same result if them are put in the fridge the same time and made to work?

[london-freddie]

Re: LG 43UF640V half picture

no visible damage to ribbons from tcon to panel, I have also cleaned them

[freakaftr8]

Re: LG 43UF640V half picture

Try cleaning the two white ribbons from tcon to panel. Also inspect those for burns or damage.

[london-freddie]

Re: LG 43UF640V half picture

ok just spent a couple of hours on this tv, can not see any problems on the two long boards fastened to the lcd panel, cleaned it, no change to picture ie on half perfect one half washed out with a tint to it.
then as I now have three tcon boards for this tv I warmed one tcon board up and tried it, result still same split picture but badside was worse virtually unwatchable
then put a board in the freezer for 10 15 minutes, result quite a good picture but still half and half
then tried the third board which had been in the freezer longer maybe half an hour, result even better picture, still half and half but nearly perfect.
using these three tcon boards each seems to give a different picture on the bad side of the screen
does that make any sense to anyone

[london-freddie]

Re: LG 43UF640V half picture

thanks for that Davi_p will get the screen surround removed again asap, however before I do, last time I looked at the two screen panels long boards I never noticed any embedded ic's on the brown flex's from board to the lcd panel so will check under the ribbons this time.
what I did see are many caps and resistors on the panel boards is there any way to test these in situ ie: without removing them from the board, I will also try cleaning flex connections to the panel on the bad side.
will post what I find

[Davi.p]

Re: LG 43UF640V half picture

"can i connect left side ribbon from the tcon to the right side of the screen to see if right side of screen then works as it should?"
NEVER DO THAT!

Chip on ribbons are on the back side... i think is not possible that mainboard can generate a faulty image only at half, this is an issue from tcon-panel, watch on the long panel's boards if there are any chip, usually buffer chips, then try to freeze them when tv ON, with a piece of food from the freezer covered with a cloth to absorb drops.. see if anything changes, don't think but try... you can do some other tests.. on the panel's ffc arrive some color signals, examples R0,1,2,3,4,5-G0,1,2,3,4,5-B0,1,2,3,4,5 they're all the bits for a pixel, if image has a green tint lets imagine that Blue bit 0 makes an unwanted connection to Green bit 5 (most significant byte) then you will have about all pixels with an high green tint, so lets imagine an image without any blue, so try to hook a pc via VGA and with a paint program show an image with all but blue colours, i'm not sure but the bit leak is possible from R5 to G0 so show an image without Red component, if it shows well there's a short somewhere, maybe some dirt on panel's boards due to washing of the screen etc... if doesn't make change there's probably a stuck Green bit always high, maybe due to faulty extern COF or a discrete like a resistor on the panel's pcb faulty... You have to check them for short/open or different tensions from other nears..

[vinceroger69]

Re: LG 43UF640V half picture

post 4 there usually on those ribbon cables

[london-freddie]

Re: LG 43UF640V half picture

will check for these ic's but will be next week now before I will get chance to look, however from what I can remember there are no ic's on those ribbons, looking at my pics of the ribbons can not see any ic's, can you ?

[vinceroger69]

Re: LG 43UF640V half picture

There is embedded small rectangular IC on each brown flexible cable between the Tab bonding board and the LCD glass panel.

In your opinion budm could a faulty cof cause this issue, as i was only guessing as not sure.

[budm]

Re: LG 43UF640V half picture

there is no chip on the panel ribbon cables

There is embedded small rectangular IC on each brown flexible cable between the Tab bonding board and the LCD glass panel.

[london-freddie]

Re: LG 43UF640V half picture

thinking but may be thinking rubbish, is it possible to send the picture from this tv to another good working tv using say a hdmi cable.
I am thinking if the second tv shows the same half picture then the fault must be in the mainboard not the tcon or panel

[london-freddie]

Re: LG 43UF640V half picture

there is no chip on the panel ribbon cables

[london-freddie]

Re: LG 43UF640V half picture

hi vinceroger69 are you referring to a chip on the led panel driver board, did look at that yesterday but did not find any shorts on it, maybe I need to look at it again
Just took tcon back out reseated ribbons and lvds cable tv came on better picture but not perfect then picture reverted back to green shaded after a few minutes

[vinceroger69]

Re: LG 43UF640V half picture

i wonder if the the chip on the panel ribbon cables is shorting that side of the tcon out?.

[london-freddie]

Re: LG 43UF640V half picture

ok got another tcon board (used), just fitted it and picture is good, great, NO after about 5 mins picture suddenly went back to same half picture perfect and half picture shaded, this time with a green tint to the faulty side
could this be the tcon warming up and breaking down, mainboard ? or screen panel ??
I am stumped on this now

[london-freddie]

Re: LG 43UF640V half picture

ok will try that ie wash it, thanks

[tiku]

Re: LG 43UF640V half picture

Ok take a soft toothbrush and a detergant powder or liquid, make a lather in a tub or a bucket, and dip T-Con in it,clean thoroughly with a toothbrush for atleast 10-15 minutes,front and back side, after that wash it under running tap water, with pressure so if there is any corrosion beneath the smd;s, it gets cleaned, then after that if you have 99% Isopropyl alcholol Solution, Dip in it for 1-2 minutes, or pour on it, so that it dries out water from T-Con, then Dry T-Con with Hair Dryer, keep it aside for atleast 10-15 minutes, then dry again with hair dryer if you are not sure if all the moisture is dried out, then you can re-connect T-Con.

[london-freddie]

Re: LG 43UF640V half picture

just warmed tcon board, no change still half picture, will have to wait for this next replacement tcon to arrive

[london-freddie]

Re: LG 43UF640V half picture

going to try heat on tcon board, after cleaning I dried it on a radiator maybe board was warm when I refitted it and it worked

[london-freddie]

Re: LG 43UF640V half picture

i have no no ultrasonic cleaner