Sharp AQUOS 70" LCD model LC-70LE550U

[Olympus620]

Symptoms: No display, no backlight, front display light blinks off once every 15 seconds
other: Unit powers on indicated by light under "Sharp" name
I purchased this TV hoping to repair it. My troubleshooting skills might seem a little primitive.....actually they are primitive but I am trying. This is what I have noticed. The remote power button and the side panel on/off switch do not toggle the power without disconnecting the cables mentioned below. If I disconnect the left side ribbon cable between the T-CON board and the panel the left half of the display and the backlights will come on and display a half perfect menu. Disconnecting the left side cable also allows the power to be cycled with either the remote control or the side panel on\off switch. When the right side T-CON ribbon cable(T-CON to panel) is removed the backlights and image remain off. Disconnecting the 4-wire cable(12v PS to T-CON)or the ribbon cable(Main board to T-CON board) also allows the backlights to come on. I am assuming since my panel is capable of displaying half an image it should be capable of displaying a complete image. I am also guessing the T-CON board has failed but would like some advice from someone familiar with Sharp LCD TV's.

I would also be eternally grateful to anyone who has a service manual for this model TV.

Thank you very much

[freakaftr8]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

Okay so I'm confused when you disconnect the right hand side ribbon cable you have a perfect left hand side of the screen? Or when you disconnect the left hand ribbon cable you have a perfect right side of the screen?

You say that when you disconnect the left-hand ribbon cable are you speaking about behind the TV looking at it from behind the left and so you have a perfect right hand side of the screen working because on sharp TVs the menu is located on the right side. Is at the side of the screen that is still working the left hand of the screen will probably either be white or black

For some reason this is sounding all too familiar...

[Olympus620]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

When the ribbon cable on the left side(viewing from back) is removed the backlight comes on and it has a good picture on the left(as viewed from the front side). The right side as viewed from the front only has the backlights and dark or black image. I don't know about other Sharps but this menu begins on the left side. I hope it is familiar enough to figure out. thanks for looking


These are the 4 cables I am referring to.

[freakaftr8]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

Do you have small thin boards that attach to the side of the panel? With the back off looking at the side of the screen do you see a small flat white ribbon cable connecting to the bottom side of each side of the panel? These boards run the length of the panel on each side there covered up by a black metal frame that surrounds the panel on each side they are underneath that frame you will be able to see the flat white ribbon cable exposed at each bottom side of the screen on the side

[Olympus620]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

I don't have access to it at night. It is to big to work on inside my home so I have placed it inside a 10x12 shed in my backyard. I will see if those boards exist in the morning. Do I need to remove any more parts to see them or should they be easily seen?

[freakaftr8]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

Have a read. Don't pull anything off the screen but just read this topic and you will see where these ribbon cables lie and you will probably get the gist of what could be going on

[Olympus620]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

I just took a look at it and the panel is surrounded by 4 thin green boards that have several cables attached per board from the front of the panel. Are these the boards you are referring to?

[freakaftr8]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

Note Vizio uses the sharp panel

https://www.badcaps.net/forum/showthread.php?t=49281

[freakaftr8]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

I just took a look at it and the panel is surrounded by 4 thin green boards that have several cables attached per board from the front of the panel. Are these the boards you are referring to?

Yes don't concern yourself with the flat green board that are attached to the bottom of the panel where the two flat white ribbon cables go from the tcon. I'm more concerned about the board that I'd attached to the side of the panel on the side you are having the problem with

[Olympus620]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

Note Vizio uses the sharp panel

https://www.badcaps.net/forum/showthread.php?t=49281

Very interesting. I need to do some reading on this but it sure sounds like my problem. I don't like that the repair is irreversible so maybe it is a "last resort". If you were me would you try any other measures first? replace the T-CON board, main or PS? I don't mind throwing another Benjamin at it if I thought it had a chance of fixing it.

[freakaftr8]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

to be honest with you your power supplies working fine as you wouldn't have half the screen if it were bad. Your main boards working fine because its supplying the signal to the tcon board or you wouldn't see anything on either side of the screen. So you're left with a panel problem. You can however disconnect that small flat ribbon cable off the bottom side of the panel connecting to the side driver on the non functioning side. The non-functioning side will be darker but you should get an image on that side with both of your ribbon cables connected from the t-con to the panel just leaving the small flat ribbon out of the equation.

Here is a picture of what you should disconnect to test off the right hand side of the panel facing the front.

[Olympus620]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

to be honest with you your power supplies working fine as you wouldn't have half the screen if it were bad. Your main boards working fine because its supplying the signal to the tcon board or you wouldn't see anything on either side of the screen. So you're left with a panel problem. You can however disconnect that small flat ribbon cable off the bottom side of the panel connecting to the side driver on the non functioning side. The non-functioning side will be darker but you should get an image on that side with both of your ribbon cables connected from the t-con to the panel just leaving the small flat ribbon out of the equation.

Here is a picture of what you should disconnect to test off the right hand side of the panel facing the front.

That is my concern, half the screen does not work under normal conditions. Without removing the T-CON ribbon cables the backlights and the panel image(verified with a flashlight) does not come on. I think Sharp might have a feedback circuit turning the TV off for some reason to protect the T-CON or PS. I have much more to learn but your threads regarding these strips are getting me closer to making a decision or two.

[budwich]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

I think you need to look at your "perfect picture" a bit closer... :-) If you can, feed you tv a signal from a test pattern (can be found on various dvd's, etc). Then do your your cable "pulls" and look carefully at the resulting picture with a given test pattern... looking for lines (vertical or horizontal), color "shifts", missing portions. You may have a powering issue such that a "weak component" is not able to drive the panel sufficiently so the system is shutting it down BUT it is more likely that you aren't seeing a "perfect picture" and that is a "hint" that there is a "panel issue" and NOT a powering issue.

Further, leave the cables at the tcon connected. At each side in the lower corners, there are smaller cables (very similar to the tcon cables that are "unclippable"). Try unplugging one of those, do you get a full picture?... Try the other corner side, do you get a full picture? You should.

[freakaftr8]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

Further, leave the cables at the tcon connected. At each side in the lower corners, there are smaller cables (very similar to the tcon cables that are "unclippable"). Try unplugging one of those, do you get a full picture?... Try the other corner side, do you get a full picture? You should.

Exactly what he said. This is completely reversible all you're doing is unplugging a cable on the side to see if the side driver is causing the problem or not

[Olympus620]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

.....You may have a powering issue such that a "weak component" is not able to drive the panel sufficiently so the system is shutting it down BUT it is more likely that you aren't seeing a "perfect picture" and that is a "hint" that there is a "panel issue" and NOT a powering issue.....

I will be working on those other suggestions this afternoon but before that I was hoping you might have an idea on how to test for an error code or error voltage. I have seen a pin labeled error on a cable that goes from the main board to the PS. Would you by chance know the default voltage I should see on that pin? If the panel is drawing too much current it may be "shutting" everything down as you said.

I also need to clarify something I said earlier about when the left side ribbon cable is disconnected from the T-CON(1 of 2) to panel the left side is as described and has a good picture but the right side has backlighting with what appears to be full brightness, not black or dark as I previously described. Here is an image with the left cable disconnected.

[freakaftr8]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

That's correct the right side of the screen is going to be full white because it has no voltage or any data being fed to it because that cable is disconnected. What you need to do is connect that cable so you have both cables connected to the Tcon board. Then disconnect the small flat cable that I showed in my previous picture. Once you do that see if you have a picture spanning all the way across the screen its going to be a little darker on the right side but you'll still see something. Do you have that or not?

[freakaftr8]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

The error pin on your power supply is either fed high or fed low. That is not your problem. The power supply is not an error protect mode right now it will be with your right side ribbon cable connected shutting down the main board due to a voltage / current condition which in turn may send your error pin high or low depending upon how is configured.

The error pin is obviously doing its job with shutting the system down with the right cable connected as it is protecting the T CON board in other various components in the TV from getting shorted out due to a panel problem.

[Olympus620]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

That's correct the right side of the screen is going to be full white because it has no voltage or any data being fed to it because that cable is disconnected. What you need to do is connect that cable so you have both cables connected to the Tcon board. Then disconnect the small flat cable that I showed in my previous picture. Once you do that see if you have a picture spanning all the way across the screen its going to be a little darker on the right side but you'll still see something. Do you have that or not?

I do:


This is with all cables connected except the right\bottom mini cable connecting the green boards together. This is the cable Freakaftr8 suggested be removed as in post #11. The image is a little dark and hard to read the menu but I now have backlights and an image on the right side as well.

[freakaftr8]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

Then you have to remove that whole sise board from the panel like I have mentioned in my posting. There is a short on one of the tab driver IC's on that side board. Unfortunately that is the only option you have.

[Olympus620]

Re: Sharp AQUOS 70" LCD model LC-70LE550U

The error pin on your power supply is either fed high or fed low. That is not your problem. The power supply is not an error protect mode right now it will be with your right side ribbon cable connected shutting down the main board due to a voltage / current condition which in turn may send your error pin high or low depending upon how is configured.

The error pin is obviously doing its job with shutting the system down with the right cable connected as it is protecting the T CON board in other various components in the TV from getting shorted out due to a panel problem.

Is the majority of the voltage/current being drawn from the LED's on the long green boards or does this TV not have LED's? I am asking because I would think replacing the green strips might fix the problem?