lg42ld450 no picture / startup fault

[daphney]

i have the above tv & it has sound ok but when turn on i get as seen in pics & rightside gets dimmer until almost same as left this takes 20secs maybe was working fine til came in & was like this it turns on & off fine but i dont see lg lifes good screen & cant access menu cant see any burnt or bubbled caps.
any ideas where to start looking?
thnx as always for the help

[tom66]

Re: lg42ld450 no picture / startup fault

I would say there's a good chance you have a bad LCD panel there. Maybe you have a tab bond issue. You can try unplugging one of the two ribbon cables going into the panel from the T-con board. If you get half a picture that pretty much confirms shorted bad panel.

[daphney]

Re: lg42ld450 no picture / startup fault

i have unplugged ribbon on side that stays black & other side works fine so panel is dead then & no repair possible?
thnx for u help as always

[tom66]

Re: lg42ld450 no picture / startup fault

That confirms a panel fault - you can try see if you can find a shorted ceramic capacitor on the panel boards, but it is probably not fixable (gate or source driver IC failure, bonded to panel.)

[daphney]

Re: lg42ld450 no picture / startup fault

would it be just 1 cap on the panel board? i had a quick look & 4 buzz from 7 on dead side will look properly later there all the bigger 1s
sorry i no that prob dont help
thnx

[tom66]

Re: lg42ld450 no picture / startup fault

Most of the time, the cap appears shorted but when removed it is OK, it is the chip (driver IC) on the ribbon which has shorted in that case; it will not be a repairable fault. It would be rare to find many caps shorted at once but one bad driver IC could make a lot of caps look bad.

[daphney]

Re: lg42ld450 no picture / startup fault

i think i may have found the culprit cap is c112 on board connected to panel but i cant find on schematic i got from net any1 no what value of this is?
thnx as always

[tom66]

Re: lg42ld450 no picture / startup fault

If it is in a similar place to other capacitors you may be able to remove a good one and compare, otherwise you will have to find a cracked screen to match against.

[mmartell]

Re: lg42ld450 no picture / startup fault

Doesn't sound like he's verified that is the problem. Wouldn't it be ok to remove it and run the set to see if the bad half of screen works ?

[daphney]

Re: lg42ld450 no picture / startup fault

i have removed c112 from board & it buzzs both ways theres 2 boards for screen 1 for left & right so would the good side have same caps? so i could try with 1 from there? & mayb measure to see what i need?
or is it safe to start tv with c112 missing just to see if works?
thnx as always

[tom66]

Re: lg42ld450 no picture / startup fault

You could try that, could you supply a clear photo of the area around the bad cap and one of the whole half of the panel.
I would not advise running it without the cap present as damage to the screen is possible.

[daphney]

Re: lg42ld450 no picture / startup fault

hope these are clear enuff best i could do
pic 1 area of removed cap 2 board from middle of tv 3 from left side
thnx as always

[tibimakai]

Re: lg42ld450 no picture / startup fault

In the first picture, there is a burn mark?

[tom66]

Re: lg42ld450 no picture / startup fault

Photos aren't really clear enough; it looks like your camera needs more light (that's why the image looks fuzzy), so try perhaps opening a window or taking the panel out into sunlight, we need to see the writing next to each capacitor and the blue traces.
Also investigate that burn mark as it looks like Tibi may have a point there... that does look a little iffy... could just be flux or something more severe.

[daphney]

Re: lg42ld450 no picture / startup fault

the burn is were i used flux pen on cap before removed wasnt there before i will try & take some better pics later & upload
thnx as always

[daphney]

Re: lg42ld450 no picture / startup fault

here are some more pics its the middle on black side of screen so last pic is middle on good side of screen just incase it helps hope these are clearer
thnx as always