Touchscreen working, or not, randomly.

[FamilyGuy]

Hi!

tl;dr:

My touchscreen doesn't work reliably and it doesn't seem to be fixed by rebooting but simply randomly. There a small gap between the bottom of the screen and the case and I wonder if it could be the source of the problem. Any advice on how to fix this?

Long story:

I got one of the first 1GHz Pandora that came in a wooden box with a message from he who shall not be named. When it arrived, the screen was cracked and the touchscreen didn't work and so I RMA it and when I got it back I tested it and it seemed to work fine. I remember one time it didn't work but I didn't care too much and tough it was a bug.

Fast forward a few years and I quite enjoy my Pandora but I never use the touchscreen. That is until I started paying StarCraft. Now I noticed the touchscreen sometimes works, sometimes doesn't work. It fixes itself after a while and then stops working seemingly randomly. I would really like to fix this as SC is great but annoying to play with nubs.

There's a small bulge or gap at the bottom of the screen between the LCD and the case, might this be the problem? If so, how can i fix that? Anyone had that kind of issue and fixed it? Any advice?

Thank you in advance!

FG

 

[EvilDragon]

The gap at the bottom is not the issue, that's the case with all the Pandoras.

I got a few ideas:

1. Make sure all the clips in the bezel are properly clipped. If not, it can cause issues with the touchscreen.

2. As you got it from Craig, it could be you got the cheap chinese AC adaptor. That one causes issues with the touchscreen when then Pandora is connected to it. Unplug it and use the Pandora with the battery to test if this is the case.

3. Can you try using the Input Tester that the touchscreen has issues? Maybe there is too much system load.

 

[FamilyGuy]

It was the right clip! Thank you!

I'm not 100% sure as my problem was intermittent, but I snapped the clip in place and it's working properly for a good while!

I'm relieved as I was considering opening up the lid!

Thanks for the great support!

 

[EvilDragon]

You're welcome Enjoy StarCraft

 

[levi]

2. As you got it from Craig, it could be you got the cheap chinese AC adaptor. That one causes issues with the touchscreen when then Pandora is connected to it. Unplug it and use the Pandora with the battery to test if this is the case.

Wow, I didn't expect it to be possible to break the touchscreen non-destructively by using a dodgy charger!

I suppose if it under-volts the supply it might not be enough to run the digitiser reliably, but I don't really understand how the charging circuitry works on modern devices.  I always though to charge a battery you supplied it with constant current (resulting in a variable voltage on the supply side), but since all modern Lithium Ion batteries only have the two pins (and the third sense pin), it can't be running the system of a variable voltage supply, so it wouldn't be able to support charging while operating.

Ah, unless it switches to running from the mains supply, and disconnects the line from the battery to v+ while on charge.  And if the mains input was under the expected voltage, that might cause system instability like this.

 

[EvilDragon]

The cheap charger doesn't conform anything, the problem here is the unclean power signal that interferes with everything.

 

[FamilyGuy]

Well, it stopped working again. I guess I celebrated too early.

I use my Pandora with the battery, not using AC power. I have now clipped the remaining lid clips. I don't know how to test the touchscreen using the input-tester, I though that was only for keys...

When it doesn't work, the touchscreen seems to half-semi-work, with the cursor appearing at the edge of the screen sometimes, correlated with the y position of my stylus.

Any help would be greatly appreciated!

FG

PS:
I have no problem RMA-ing my pandora if need be, I'd just like to know a cost estimate and a guarantee that it'd be fixed.

 

[TrashyMG]

Could also try checking if there is any crud between the bezel and the LCD screen. Sometime a small bit of dirt on the edge of the screen could cause an issue. 

 

[EvilDragon]

if it's at the edge (especially the top middle), it's most probably a clip not properly sitting (or some crud)

 

[FamilyGuy]

Right now the zone that's not working is roughly 30% of the screen width and 40% of its height. It's located at the bottom right of the screen, with a ~5% strip that works at the right of the "broken" zone...

Everything looks flush, except the bottom edge of the lid, and it's not noticeably dirty either.

I can't really wrap my head around this...

 

[EvilDragon]

Hmm, that's weird. Did you try calibrating it while it had an issue? Because in that case, the calibration messed up.

 

[FamilyGuy]

To answer the old question: I didn't touch the calibration.


So it still does work only sometimes. I sure enjoy my Pandora for some retro gaming, but I'd like to put the touchscreen to good use in StarCraft, among others.

Is there any way I could have this fixed without spending hundreds of dollars for shipping and a new screen/touchscreen?

I'm in eastern Canada.

 

[NutNut]

If you can somehow take a short video of the input->response of your touchscreen, it will be easier for us to figure out what may be wrong. Just a video of you doing a few random pokes and swipes should be enough.

 

[FamilyGuy]

If you can somehow take a short video of the input->response of your touchscreen, it will be easier for us to figure out what may be wrong. Just a video of you doing a few random pokes and swipes should be enough.

Hopefully this is enough.
When I started playing starcraft, it did work, but after around 2 minutes it started behaving like in the video, and it still does up to now.

Thank you!

FG

 

[TrashyMG]

To me I'd check the left side of the bezel, a bit of crud between the bezel and the touchscreen may be intermittently touching causing the cursor to go left. Run a folded piece of paper in the gap to clean it out or perhaps loosen the screws on the left side to crack it open a bit to get a cleaning brush in there or something of the sort.

 

[NutNut]

I do not think it's likely that this problem is caused by crud buildup, as the cursor should land halfway between crud and stylus if that were the case.

My uneducated guess is that it's a connection issue with one of the two connections for the touchscreen x axis, between touchscreen and controller. Apparently I haven't lurked long enough, as I do not know where the touchscreen controller is located on the Pandora, but I believe the problem lies in one of these areas:

• Solder connection from touchscreen ribbon cable to lcd ribbon cable
• Ribbon cable connection/socket on the lcd board
• Ribbon cable connection/socket on the main board (assuming the controller is there)
• ...Or it could be a bad touchscreen
  
• ...Or it could also be a bad/broken ribbon cable (unlikely, I'd think)

Disassembling the unit and reseating the ribbon cables seems like the easiest course of action for now.

 

[TrashyMG]

I've had this same problem on a couple of my Pandoras and resolved it just like I described.

 

[FamilyGuy]

I've had this same problem on a couple of my Pandoras and resolved it just like I described.

I'll try it soon. I plan on loosing the lid screws and wiping the bezel sides with a kimwipe. I could also use isopropyl alcohol (IPA) is this a good idea?
Any more info before I do it?

 

[TrashyMG]

I could also use isopropyl alcohol (IPA) is this a good idea?

I'd just stick to water to be safe, especially if the IPA content is over 60%.

 

[FamilyGuy]

I'd just stick to water to be safe, especially if the IPA content is over 60%.

Pretty much 100%, so water it is!