le40d503f7w screen problems help appreciated

[beliver]

hi tv 40 in lcd green banner across top about 3rd of screen plz help if u can thanks in advance.

[beliver]

Re: le40d503f7w screen problems help appreciated

plz help anybody?????

[sordids999]

Re: le40d503f7w screen problems help appreciated

i think it looks like panel failure or even tab bond

[beliver]

Re: le40d503f7w screen problems help appreciated

right have open tv can locate 2 tabs should there be more ???
have seen the video how to repair if this is the tabs.
but can only find two coming of long pcb sorry total newbie lol

[beliver]

Re: le40d503f7w screen problems help appreciated

update after about 15 mins veiwing after inital warm up screen ok and bar vanishes.
so my question could this still be the panel faliure???
thanks in advance

[nomoresonys]

Re: le40d503f7w screen problems help appreciated

could be bad capacitor, they dont have to bulge to be bad.

[beliver]

Re: le40d503f7w screen problems help appreciated

the capacitors are cheap is it just easier to replace all ???

[saddle_au]

Re: le40d503f7w screen problems help appreciated

What are the tab bonds?

Background info.

Your LCD panel needs to drive an awfully large number of horizontal and vertical lines so that individual pixels can be addressed. You cannot do that easily in a parallel way, so they have a scheme where main boards clock data on a couple of wires at high speed to a timing and control board (TCon). TCons take that in and reclock it in a particular way on 80 to a 100 wires to the panel and the panel itself has to take the 80 to a 100 and turn them into 1000's of lines.

There will be two or more cables from the TCon board to the panel, but there are chips on the panel itself, usually embedded in flat cables sticking out two or three sides of the glass. One side of the panel usually attaches to a PCB (top or bottom) via 4/8/12 flat cables which is used to spread the signals from the TCON to wires on the panel. There are chips on those flat cables and the cables themselves are not socketed. They are called tab bonds and are joined to the PCB and the panel by a gluing process that allows vertical current flow in the glue but not sideways.

This glue fails sometimes and re gluing it is virtually impossible for you and me due to the ultra fine tolerances, special temperatures/pressures required and the cost/getting some of the tab tape.

He's one being attached https://www.youtube.com/watch?v=jorqLkOVI6Q

Tab chips on the top of the screen convert information to column lines and there are also tabs on the sides of the screen where chips on the tabs convert signals into row information.

Any of these can fail and the screen becomes a throwaway. Sometimes the chips on the tabs fail (throwaway), sometimes the chip has not failed, the connection from the chip to the tab fails and can be maybe recovered with pressure (permanently push on it somehow) but this usually is temporary, although Sony 46 inch screens seem to go years after pressing on column tab chips which is what usually fails.

Hope this helps.

[nomoresonys]

Re: le40d503f7w screen problems help appreciated

update after about 15 mins veiwing after inital warm up screen ok and bar vanishes.
so my question could this still be the panel faliure???
thanks in advance

doesnt seem like panel failure, panel failure is more constant.

[nomoresonys]

Re: le40d503f7w screen problems help appreciated

the capacitors are cheap is it just easier to replace all ???

lots of folks just replace them all to eliminate the possibility.

[beliver]

Re: le40d503f7w screen problems help appreciated

cheers guys appreciate help