Sharp LC46D82U Distorted Image

[LDSisHere]

Hello,

I was given this TV from a pile of stuff going to a recycler. I am not sure which board(s) could be causing this type of image problem so I am hoping that I could get some input from the forum. I am just hoping it is not the panel.

Thanks.

[retiredcaps]

Re: Sharp LC46D82U Distorted Image

I am just hoping it is not the panel.

Clean and reseat every internal connector.

If that doesn't work, try flexing the outside frame to see if the problem goes away (think tab bonds) like my Toshiba

https://www.badcaps.net/forum/showthread.php?t=19939

The only bad thing about this type of tab bond "repair" is that may or may not last?

[tom66]

Re: Sharp LC46D82U Distorted Image

It's not the panel, it's the main board or the motion processor (sub T-con.)

First try a reset:
- Hold INPUT and CH- while TV is off (red light is OFF) on top controls
- Turn TV on
- Will take approx 30 secs to boot -- keep holding keys down
- If "K" appears continue if not repeat the previous steps
- Release the keys
- Press VOL- and CH- on the top controls
- The service menu should appear
- Select EEP CLEAR and FACTORY RESET -- buried away in menus

[LDSisHere]

Re: Sharp LC46D82U Distorted Image

Well I took it all apart to re-seat everything as I had already taken the main board out last night. Now it will not completely power on, it turns itself off before it completely starts. I have double checked all the connections several times to no avail.

It is however flashing a code on the front LED's. I have attached the codes from the SM.

Power LED OPC LED

ON ON

ON ON

OFF ON

Pause.

Repeat this cycle continuously.

Per the service manual, if I am reading it correctly, this indicates a failure of the 5V regulated power on the main board. The 5V regulator is fed with 6V from the power supply. So I checked both the PS output and the regulated output on the main board, but they all appear good enough.

PS Voltages

6V = 6.075

12V = 12.33V

10V = 10.02V

13V = 13.45V

AC_DET = 3.332V

BU5V = 5.001V



VR voltages

9V = 8.97V

5V = 4.987V

3.3V = 3.293V

Since it would not power on, I could not get it to the service mode as Tom66 suggested. I am now thinking a new (used) main board would be my first step in getting this unit operational, unless it is possible to repair this one.

In case anyone is wondering, all the through caps I have seen are good name brands with no known bad series. I went over the ones on the power board with my Blue ESR tester, I did replace one 50V 47uF cap but I was not sure it was bad, it just had a higher ESR than the Nichicon PW I used to replace it. I did this was before I took the pictures I used in my original post so it should not have anything to do with my current problem.

So I guess what I need to know is if I should just try and find a good board or take a stab at repairing this one?

Thanks!

[retiredcaps]

Re: Sharp LC46D82U Distorted Image

I have double checked all the connections several times to no avail.

1) Take apart all your connections again and verify that none of the pins are bent and that no cables can be inserted in backwards. Most, if not all, the cables should be keyed making it very difficult to insert backwards, but you never know?

2) Use your posted picture as a guide in case some connectors are identical.

3) Make sure all your screws are back in for proper ground.

4) There is a pin called PS_ON (in schematic). This should be toggled high (usually > 3V).

5) I'm assuming PNL_POW is the signal to turn on the backlights? What is the voltage reading on this pin?

[LDSisHere]

Re: Sharp LC46D82U Distorted Image

1) Take apart all your connections again and verify that none of the pins are bent and that no cables can be inserted in backwards. Most, if not all, the cables should be keyed making it very difficult to insert backwards, but you never know?

2) Use your posted picture as a guide in case some connectors are identical.

3) Make sure all your screws are back in for proper ground.

4) There is a pin called PS_ON (in schematic). This should be toggled high (usually > 3V).

5) I'm assuming PNL_POW is the signal to turn on the backlights? What is the voltage reading on this pin?

I have been meaning to come back an update this post. Your were absolutely correct about mixing up the cables. I am completely disgusted with myself over this stupid TV.

I did not see that there was two cable with identical ends that were placed so they could easily be interchanged, I thought that all the connectors were unique. One was supposed to go from the power supply to the lower T-Con and the other one to the main board but I had swapped them. I discovered this after I had purchased a new main board which I thought and may well have been the source of my problems. After applying power to the incorrect ports of the old main board, it was for sure toast. The new main board seemed to operate correctly as best as I could tell. I no longer had any blink codes at any rate.

I still did not have any picture so I thought that the T-con board I had put the wrong connector too was the problem and I got a replacement for it. Still nothing on the screen nor back lights. The back lights on\off is controlled by the top T-con board and I could turn them on manually but they would only flash for a fraction of a second during the start up sequence. So with the top T-con board being the only one I had not tried I got a replacement for it. It changed nothing.

At this point I am not sure what I should do, so I have set it aside for a while. I do not want to throw any more money at it, I do not know if one of my "new" boards is bad, or if my cable mix up permanently damaged the screen itself. The way this TV is made with the boards being stacked on top of each other makes it very difficult to probe while it is operating which just adds to the frustration.

This adventure did however teach me several valuable lessons that I hopefully will not soon forget.

[retiredcaps]

Re: Sharp LC46D82U Distorted Image

Your were absolutely correct about mixing up the cables.

When I take apart something, I take lots of pictures.

I use different felt color markers to mark up the connectors just to ensure I put them back properly. If you only have one marker, just mark up different parts of the connectors for each board (left end for one connector, right end for another connector, middle for another).

For tough projects, I sometimes set them aside and look at them later once I get more info.

[LDSisHere]

Re: Sharp LC46D82U Distorted Image

If you only have one marker, just mark up different parts of the connectors for each board (left end for one connector, right end for another connector, middle for another).

I normally do this if I think there are identical connectors that could get mixed up.

For example, when I first started trying to work on computer monitors I would mark the CCFL connectors so I could put them back in the same sockets. After disassembling my first screen and seeing what the wires were going to, I stopped doing this on monitors.

In the case of this TV I was rushing and tired and failed to notice that the connectors were the same. The fact that one connector only had three of eight holes filled also contributed to my failure to notice they were the same.

When I was starting to connect my replacement main board was when I noticed they were the same and thankfully I was able to use my pictures to see where they were supposed to go.

I have found that I usually make my dumbest mistakes when I am overly tired so I am going to try and keep this in mind for the future. My projects seem abnormally hard to repair as it is, me adding to the problems is for sure a bad way to go. The only thing I do from here is just to learn from this experience and not repeat it.

[2tank]

Re: Sharp LC46D82U Distorted Image

Hi, I'm having the same (or thereabouts) issue with my lc46d82u. I replaced my t-con and the board under it that drives each quadrant of the panel. I thought this would fix it because the old t-con board looked like it melted its thermal compound off. It still has some noise/ghosting in the image almost exactly like yours. Did replacing the main board fix your issue? If so, where did you find the main board for this set? I've tried unplugging and replugging the ribbon cables (cleaned with compressed air before reinserting) which did not change the problem. I can post additional pictures if necessary. Thanks for the help.

[LDSisHere]

Re: Sharp LC46D82U Distorted Image

No, I never did get this TV working. Before I ever got back to it, the screen was damaged when my kids were moving stuff around in my garage.

[2tank]

Re: Sharp LC46D82U Distorted Image

After getting a different main board and analog input board, I got some good news and bad news. The good news is the new board functions better than the old one. The bad news is that there is still some unhappy pixels across the top of the panel. The unhappy pixels go away when an OSD menu is up on top of them, but they are displayed on HDMI and RF inputs.

I then disconnected and reconnected the cable that goes from the main board to the T-Con board while the set was on. This is the cable that is made up of what looks to be enameled copper magnet wire. I've included a picture of this cable. The set shut off after blinking the green power led. When I powered it back on with the power button, all was good. I power cycled it with the power button and it remained good. I power cycled it by removing and replugging the power cable, all was good. It remains 100% and I am now viewing over-the-air HDTV as I type.

I'll turn it off tonight, leave it plugged in, and test it in the morning. I'm going to leave the back cover off just until I'm sure it will stay fixed. I believe I would like to look for a new one of the cables I show in the picture. I'm not sure why unplugging and replugging while the set is on should have the effect of fixing the problem. I have replaced the T-Con board, the Driver board that controls each quadrant of the panel, the Main board, and the Analog connections board. If anybody has any ideas or suggestions of where to go from here, I'm all ears (or in this case eyes).

See pictures and let me know your thoughts.

[2tank]

Re: Sharp LC46D82U Distorted Image

It was fine for about 30 minutes, then developed some static. When OSD menus were displayed, they had some random moving static (singular pixels) and when they went away, the picture returned to perfect (no moving or stopped static). I then cycled through the menus some more (menu displayed/menu not displayed) and the set started to develop more and more static lines and had some moving singular random pixel noise. I've posted 2 pictures of both circumstances.

Picture 1 of the Input Menu shows what a clip of the random moving singular static pixels looks like.

Picture 2 shows what the signal looks like after exiting from the Main Menu. These pixels are stationary and occur in horizontal patterns. When going to menu again, they move to a new fixed position, when exiting the menu, they will move again to new positions and stay there.

Has anybody ever seen this behavior before?

[freakaftr8]

Re: Sharp LC46D82U Distorted Image

This is the mainboard. Near the lvds cable. Press and.pull on the board while on. Problem will change in the picture. A ram chip has a bad BGA connection issue.

[2tank]

Re: Sharp LC46D82U Distorted Image

Applying pressure to various chips on the Main Board does affect the patterns. All the dynamic noise can be changed or goes away by varying pressure on different chips near the LVDS cable. I tested this procedure with the 3 chips that are covered by the heat sink and a few others near the top of the board. I can confirm that flexing the board in the top half temporarily fixes the moving interference patterns.

The short stationary lines of pixels are unaffected by this procedure. They are only changed by going into/out of the menus as before. I cycled the menus while pressing the chips and have managed to make all the noise go away.

This is a great step on the road to being completely fixed. I guess I will have to try another Main Board, since both of these issues seem to be coming from it.

Thanks for the continued thoughts. If anybody knows where I can find a known good Main Board for this set, I would be happy to get one.

[freakaftr8]

Re: Sharp LC46D82U Distorted Image

I removed the screws to the top board. Put a piece of wood behind affected area and screwed board back down flexing the board. This fix is still working today after many months of use. Of course it's probably a temporary fix but it works.
Until I can get brave enough to try to reball.

[2tank]

Re: Sharp LC46D82U Distorted Image

I'll go make a couple different size spacers for it tomorrow and install when I get home. I measured the distance from the top of the frame to the bottom of the board (less component height) as about 0.279 inches. I'll double stick tape the spacer to the metal frame then screw the board down.

I'll try various configurations and post the results.
---

I have access to our SMD rework station, so I may try to heat up the solder connections to the chips on my "extra" (original) board that came out of this set. I will post those results if I get time to reinstall.

[2tank]

Re: Sharp LC46D82U Distorted Image

I made some different thickness spacers today. I installed one at the top middle of the Main Board. It works for the most part, I saw about 20 seconds of green lines all over ( happened twice but for very short periods). Unfortunately, this didn't happen until I had the set buttoned back up. I'll leave it how it is because it has been performing fine for the past few hours and I don't feel like ripping it apart again right now. If it acts up any more, I'll update this forum when I deal with it again.

I am still looking for a new Main Board just in case, for the right price.

Thanks again for all the help and ideas.

[freakaftr8]

Re: Sharp LC46D82U Distorted Image

No problem. It's a cruddy fix of course and not usually the way I would normally repair an issue but given the track record I have with fixing BGA issues it's safer and not perminant. Lol