bad touch screen area

[Carlos FL]

My touch screen has a rectangular area that misbehaves.

If we set the lower left corner as (0,0), the rectangle is between (4.5,0) cm and (7,2.5) cm.

If I touch the screen inside this area, the pointer is displaced by approx. 3 cm to the right. 

Out side this area the touch screen is good and very accurate.

 

[mcobit]

Any dirt between the bezel and screen? Are all the clips that hold the screenbezel in place snapped in correctly?


Also you can try to reseat the lcdcable or recalibrate the touchscreen.

 

[Carlos FL]

No dirt. I have this Pandy for one week and it is still pristine. 

The screen mount looks perfectly flat and snug, there is no gap and nothing is loose.

I recalibrated the touchscreen a few times, but the central calibration point is well above the problematic area.

The problem area is so well defined that it looks to me like this interference issue described by ED:

 http://boards.openpandora.org/index.php/topic/11753-touchscreen-acting-weird-at-a-certain-spot/#entry218578

Can you guide me on how to reseat the LCD cable?

 

[thatgui]

Maybe

https://www.youtube.com/embed/videoseries?list=UUXcGSUSo0TNaSGylCVidD3w is of help here

 

[Carlos FL]

Thanks Thatgui.

The video taught me two things. One, I am afraid of handling the screen. The small things look really tricky and I think I would break a couple of units before my clumsy hands get the hang of it. It also clearly showed that the problem area is right in front of the speaker board.

So I think the problem is not related with contact issues in the LCD cable, but is more related with interference with the speaker board. I looked against the light and I noticed a little bit of bulging of the screen, so I loosened up the screws, as ED recommended. Now, if I touch very gently with the stylus, the touch screen reacts correctly one time out of three or so. 

Since the screws now are barely holding the frame and I cannot see any bulge anymore, this is as far as my repair skills can go a the moment. I think I will contact ED and Link and see if they can help.

 

[Link]

If you look at the top of the screen, there are three clips that the front of the LCD housing (with speaker vents) connects to the back of the LCD housing, forming the hinge at the base.  At  10:30,12 O'Clock  & 1:30, there are clips, are they all clipped in?

Sometimes you might be able to push inwards on these areas, causing them to click into back part.  So you are pushing in on the front part while pulling upwards on the back piece that forms the edge if you can visually see the clips that aren't seated properly. 

Hope this makes sense. 

 

[Carlos FL]

All clips are clipped in.

I tried to push them further, but nothing moved. They seem really well mounted.

I tried to take a picture, but the focus turned out bad:

https://docs.google.com/file/d/0B7r5FPYJ7sJwZzFUTGI0TmZ3MlE/edit?usp=sharing

The screen looks flat, but the problem continues.

 

[Link]

It was the clips.  On its way back. 

 

[Carlos FL]

New chapter in this saga.

When Link received my unit for repair, all 3 top clips were off. They got unhinged during shipping. He clipped them back and the unit tested OK. But during shipping back, despite it being protected by a large package, the same 3 clips got unhinged again. My suspicion is that the unhinging was caused by the screws not being tight, since I had forgotten to re-tighten them after my test described in post #5 above.

So, I clipped them back, but the problem returned. I tightened the screws and there is almost no difference. The affected area seems a bit larger now.

I made 2 videos to show the defective area and the good area of the screen.

Here is the first one showing the problem in centre bottom area (no sound):  http://youtu.be/QgfCL9uwaZw

And here is one showing how the touchscreen works well in the top area (no sound): http://youtu.be/OJ8z-Dv8pO4

The same problem happens with the stylus or my finger and I am only applying a mild pressure. It also happens in all applications and games.

I did notice a small gap on the bottom part of the bezel (as shown here ), but unlike in that case pressing on the bezel there does not help.

Any more ideas?

 

[Link]

bump

 

[gotwake424]

bump

Link did you re-seat the lcd connector to the main board when he sent it to you (13 in the pic below)? I have a feeling there is dirt/dust in the main connect for the lcd ribbon cable and that might be fouling up the connection? 

Maybe try blasting it with air and re seating the lcd cable 

 

[Link]

^

I didn't have to open the unit.  Clipping the clips back in solved what I thought was the only problem.  I don't normally test touchscreens that elaborately.  The cursor responded to my taps, so I wrapped it up and sent it back.  I tested all over the screen with my taps but perhaps I should have checked under the hood too.  Maybe he'd be willing to try this himself, your solution.

 

[gotwake424]

^

I didn't have to open the unit.  Clipping the clips back in solved what I thought was the only problem.  I don't normally test touchscreens that elaborately.  The cursor responded to my taps, so I wrapped it up and sent it back.  I tested all over the screen with my taps but perhaps I should have checked under the hood too.  Maybe he'd be willing to try this himself, your solution.

Just wondering because if you had re seated it, then there would be no point in him trying it 

Opening up the case to get to the main board is way easier than opening the screen section, so i recommend he try this is he feels comfortable with it 

 

[Carlos FL]

Thanks for the hint, Gotwake.

I found the video about the screen really intimidating. Opening up the case seems less so (no messing with the antenna).

I will give it a try.

To clarify, re-seating means just pulling it out, air-blasting, and pushing it back in, right? 

 

[gotwake424]

Thanks for the hint, Gotwake.

I found the video about the screen really intimidating. Opening up the case seems less so (no messing with the antenna).

I will give it a try.

To clarify, re-seating means just pulling it out, air-blasting, and pushing it back in, right? 

Yes it does.

You only have to open the bottom portion of the pandora to re-seat it ( should be like 4 screws, make sure you don't over tighten them when you put everything back together)

 

[Carlos FL]

To clarify, re-seating means just pulling it out, air-blasting, and pushing it back in, right? 

Yes it does.

You only have to open the bottom portion of the pandora to re-seat it ( should be like 4 screws, make sure you don't over tighten them when you put everything back together)

OK, thanks. 

I will report back after doing it.

 

[Carlos FL]

I am reporting back on my faulty touch screen issue.

It took me almost a month to perform the re-seating of the screen cable, because I wanted to do it in the electronics shop of the university to be absolutely sure it was done right. In the meantime, I kept using the Pandora with the nubs and I noticed the screen problem increasing and the affected area spreading from the original rectangle in front of the speaker board. Now almost every area of the screen would sometimes respond correctly and other times have this shift to the right.

Earlier this week I had time to go to the shop and the technician very carefully (!) pulled out the cable, cleaned the contacts, air-blasted the socket, and re-seated the cable. I was watching and he used the utmost care. 

Unfortunately, it made no difference. The screen still shows randomly a position bias with the stylus, even after repeated calibrations. Since nobody else seems to have had this problem and the problem got worse, I think it is a faulty cable.

 

[CocoCreekFisherman]

I applaud you for your diligence Carlos FL 

 

[Carlos FL]

Happy ending to the saga.

Link replaced the faulty screen under warranty.

Ultra-precise touch now.

Happy as a dandy.