SHARP LC-60E79U display goes from washed out very grainy to white

[shelby5041]

hi

i have had this tv for a while ....am finally getting to trying to repair

when powered on the tv powers on fine but the display is totally washed out...and you can barely see the image and then the screen eventually goes to almost all white

any ideas?

i have been told it could be the lcd screen boards shorting on metal frame but when i look it seems its not touching frame at all

fyi i replaced with a used tcon board but did not change anything but board was used so no guarantees it was a good board

and there is power going to tcon board i tested it a while back

before i toss out tv i want to make sure its not a bad lcd panel.....if it is bad lcd panel of course tv is worthless and would toss out

see photos

any help would be appreciated

[dskall]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

T-con made no difference? Does unplugging one ribbon cable at a time make a difference?

[shelby5041]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

hi it has been over a year when i last messed with the tv and now i have time to maybe fix it

what would removing cables from tcon show?

what should i look for ?

like


if it does this then its this

or if it does this then its this

[Andrew F. Ali]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

It would tell you if the panel is bad or not. However, from the pics it looks like bad panel. Make absolute certain you reseat the cables properly and they aren't twisted/crooked or anything.

[shelby5041]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

hi i removed the left side cable

and here is the pic

the tv is upside down in the photo so the right side of the pic is the left side cable i removed

all i want to do is see if the panel is bad....if panel is bad then i will obviously toss tv

but i have seen people say that the panel boards short out against metal and that can cause the symptoms i have

tjhe side of screen i left plugged in starts pure black and then gets this funky colorization but the colorization fills more and more of that side of screen as tv warms up and the side of the screen i removed cable starts off white with a few random thin vertical lines and then after a few seconds goes to all white

i do appreciate all and any advice

thank you

[shelby5041]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

could it be the main board? Tcon? power supply?

can i test to rule these out?

[shelby5041]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

and one other thing i noticed....the main board and power supply have a very high resale value on ebay each goes for about $100.00 us...which nowadays is pretty high....this could tell me that these boards fail a lot....and thats why higher priced

[budwich]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

what happens when you do your "cable disconnect" test on the other side?

[shelby5041]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

i will disconnect cable on right side right now and let u know

[shelby5041]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

ok if i connect left side cable and disconnect right side cable

the left side is black but then after a few min it starts doing the weird colorization like other side did

and the right side is all white...with a few very faint vertical patterns but they go away after a minutes to pure white

pretty much mirrors what i did earlier

[shelby5041]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

actually after even more time the left side goes all black....after some brief weird colorization that it does...reddish


and if i hit osd...nothing appears on left side of screen nor did it on the right side when i had right side plugged in....

when i had both cables connected i would faintly see images and osd....but eventually they disappeared

[shelby5041]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

and if i remove both cables the screen is not black black but actually just dark and you can see that the backlights are on but screen is dark.....

[Davi.p]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

The thing about the board touching metal can be that like many the band boards on top of the screen (on the profile's face) with the time can dilate, make a curve and touch on the bezel metal frame, so you have to dismantle that frame to see that and aventually loose the screws that firm that board to plastic chassis.

"high resale value on ebay ... ....this could tell me that these boards fail a lot..."
this can tell you also only that boards are not so widely available..

[budwich]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

doesn't sound good. these set will normally produce a white screen for the side that is unplugged. It should be relatively stable. you should probably feed in a known signal (test pattern or equivalent). if you look along the bottom, there should be some little edge boards running along the bottom. These will be connected to the tcon AND also to other panel via bonded tabs / drivers. The boards (maybe two per half of the panel) are connected with "clampable flex cables". Try disconnect one of those clamped cables ... this will isolate the corresponding side along with some of the bottom. The picture may correct depending on the possible failure.... go from there.

[shelby5041]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

budwich

it does produce a white screen on the side that cable is unplugged

obviously when both are unplugged the lcd panel would have zero power to it and have the natural darkish lcd panel color...with backlights kind of showing through like ambient..correct?


the pure white can only be produced if the lcd panel is getting some type of power

or am i wrong

[Davi.p]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

An lcd screen unpowered shows only white (all pixels off).

For the type of defect it seems to me a panel power supply problem, for example the lack of pixel's source or drain signal, you'll never discover nothing if you doesn't dismantle the bezel.. have you done it? Since the substitute tcon is used, you have also to test power supply test points, like AVDD, VGH, VGL, VCOM, V3D3, V1D8, VGMA's or similar names.. Has to be checked with and without flat cables connected..

[dick_barton]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

+1
I agree. It's time to get the meter out and do some testing which could lead to a diagnosis. And some photo's of your circuit boards.

[Andrew F. Ali]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

The panel is bad.....Part out and sell the Main Bd and PSU while you can still make a little money.

[budwich]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

budwich

it does produce a white screen on the side that cable is unplugged

obviously when both are unplugged the lcd panel would have zero power to it and have the natural darkish lcd panel color...with backlights kind of showing through like ambient..correct?
the pure white can only be produced if the lcd panel is getting some type of power

or am i wrong

let's back up a bit...
you said
"and the right side is all white...with a few very faint vertical patterns but they go away after a minutes to pure white"

I said a disconnected panel (implied side) would show a STABLE white. How are "very faint vertical patterns" a "stable white". I don't think they are the same. Is it a problem? Potentially. Does it show EXACTLY the same with the cabling "reversed" (ie. the other side unplugged, and the previously unplugged side plugged back in)? Yes, if both tcons cables are unplugged at the same time, the screen will not go white as there will be no power to the panel.

The purpose of unplugging cables is to detect whether there is a possibility of a bad panel as doing a lot of voltage measuring won't really tell you much about a bad panel. The measuring will give you some understanding about the supporting circuitry but it is not without hazard.... hence, trying to do some "high level checks" is usually good especially with sharp panels which seem to have some issues around the tab drivers.

Anyways, I wouldn't give up just yet on the panel even if it is a bad panel as you will find a few threads where people have saved the 60" sharp by removing the bad tabs.

However, it does potentially appear to be a bad panel as some have suggested. Its whether you can determine what is bad about the panel... and whether it can be saved therein.

Still further, as suggested, if the bottom edge boards / tabs have been "wetted" or otherwise, then these will corrupted the display in various manners... have you checked these?

[freakaftr8]

Re: SHARP LC-60E79U display goes from washed out very grainy to white

Something is loading down the panel if it is the panel itself. Low voltage driven to the panel's power from the t-con board could be a problem. We are left here with only thinking that it could be a t-con board in a can be a panel problem. Since you have already replaced the t con board with no change I'm only implied to think the panel is bad

Of course I'm only speaking on the basis that this design with its implied voltage controlling all the driver Ic's connected to the panel may act similar to a plasma receiving low voltage where the whites get washed out and a lot of pink and blue mal discharge.

The problem with this is it looks sort of like a gamma processing problem however it's hard to tell because the black levels are tinged with green and pink. I wonder if there is some secondary control of gamma located on the FRP boards connected in the panel