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NST: erratic or unresponsive touch-screen (and it's not caused by dirt)

17th May 2014, 11:21 AM   |  #11  
Renate NST's Avatar
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Hmm, that doesn't look too bad.
Do this in an ADB shell:
Code:
cd /sys/devices/platform/i2c_omap.2/i2c-adapter/i2c-2/2-0050
cat ledlevel
echo 1 > forcecal
cat ledlevel
You can do this with the Touch app running.
Touch (and release) afterwards to see if the V in the center disappears.
Post the ledlevel responses.
17th May 2014, 01:18 PM   |  #12  
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Quote:
Originally Posted by Renate NST

Post the ledlevel responses.

First ledlevel (before "forcecal"):
Code:
09 09 104 111 06 08 095 105 05 05 100 106 03 03 102 087 03 05 088 089 06 03 098 082 03 05 090 075 03 03 093 084 05 06 095 088 08 09 090 092 09 09 097 098 

15 03 054 103 02 01 100 106 01 01 117 115 02 02 112 099 02 01 095 102 01 01 099 105 01 01 108 107 01 02 101 104 15 15 009 010 01 01 087 096 02 03 108 094 02 03 097 095 01 02 118 102 03 03 087 084 11 12 065 086
Second ledlevel:
Code:
08 08 071 078 05 06 079 076 03 03 078 076 02 03 075 082 03 05 080 087 05 03 080 075 03 03 092 073 02 03 082 081 03 05 078 067 06 09 080 090 09 08 095 088 

15 02 050 075 02 01 087 079 01 01 086 082 01 01 101 087 02 01 078 100 01 01 097 077 01 01 079 080 01 02 094 089 15 15 008 009 01 01 083 090 02 03 087 079 02 02 078 077 01 02 086 082 02 03 076 077 12 12 094 082

I didnt notice any changes in the touch screen after the ADB commands, even after a few touches. I restarted the Nook and ran the touch utility again, still no changes. The same pattern is still there.

Marco
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17th May 2014, 01:49 PM   |  #13  
Renate NST's Avatar
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I've been playing with my problem Nook and I've gotten it a lot closer to working.
The mechanical alignment of the components is very critical.
It's all held together with double stick tape.
Especially the top end is sensitive, that has the biggest span of plastic in the IR (internal) bezel.

But I don't think that this is your problem.

Quote:
Originally Posted by marcoNST

Code:
... 01 01 108 107 01 02 101 104 15 15 009 010 01 01 087 096 02 03 108 094 ...


Your problem is clearly related to the left side (LED side) at the vertex of the V.
The two LEDs on the left, above and below are getting a fine response out of the two photodiodes on the right used by the problem V.
Put on your reading glasses and look very closely at the left edge of the V for anything odd.
There could be dirt internally between the internal edge of the bezel and the LED.
The LED itself could be semi-fried.
The LED driver could be semi-fried.

Depending on how sensitive a camera (and how lousy an IR cut filter it has) you have, you might be able to see the problem that way.
In a darkened room, point the camera as low as possible towards the left edge.
With your finger on some part of the screen you might be able to see a dull red flickering.
My cell phone can see that if pointed directly at the LEDs on the disassembled unit.

There is also the trick of using a photodiode on a mic input to a PC.

Oh, a new version of Touch.apk
It doesn't show anything different, it just updates periodically without a touch.
That's helpful if you want to try pushing on the case to see if things change.
Attached Files
File Type: apk Touch-1.0.apk - [Click for QR Code] (11.3 KB, 13 views)
Last edited by Renate NST; 17th May 2014 at 02:42 PM.
17th May 2014, 02:53 PM   |  #14  
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Quote:
Originally Posted by Renate NST

Your problem is clearly related to the left side (LED side) at the vertex of the V.

There is also one dashed grey line at the top of the screen.
Could it be part of the same problem?
Should I look for dirt in that area too?

OK, I inspected the area (without camera).
The edges of the screen are made by 2 layers: the hard plastic black casing that touches the screen and the rubber-y dark grey wrap material glued above it. Well, because of the heat (most likely!), the glue has lost its grip in some parts (so much so that i can slide a needle in these parts), including the LED area and dirt has crept in. I removed some of the dirt with the needle.

The hard black casing is still well attached to the screen.

I still have the same LED pattern. Is there a safe way to open the Nook and remove the dirt?
At least i can exclude one cause.

M.

M
Last edited by marcoNST; 17th May 2014 at 04:17 PM.
17th May 2014, 04:29 PM   |  #15  
Renate NST's Avatar
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The very top and bottom horizontal lines have a couple of bad design problems working against them.
I wouldn't be surprised if all Nooks had problems there.

The optical problem with dirt would be dirt on the face of the dark green inner bezel.
If you have dirt under the bezel that would relate to a physical problem affecting the optical alignment.
Use the new version of Touch.apk and see if you can squeeze the case at the bad spot and make the V disappear.
Try also bending (lightly) the edge backwards and forwards.
Do this and also try doing a echo 1 > forcecal at the same time.

If you have to take the bezel apart to try to fix this you'll be opening up a whole new can of worms.
That's what I'm trying to solve with my 2nd Nook.
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19th May 2014, 03:44 AM   |  #16  
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Hi Renate,

I tried your solution (repeat the forcecal), but no joy.
At this stage, I am going to get a new one (or second hand) very soon as I really need a functional reader for my travels and Nook suits me well.
But I wanted to thank you for your help and good luck recovering yours!

Marco

P.S. Also I need to thank you for your Library app, I have been using it since rooted and loved it!
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