N800 touchscreen unresponsive
 

I'm going through a few N800s that I have to disposition. One is a device that was reported not to have a bluetooth ID during QA but was discovered later to work properly even though the ID doesn't show in the About app.

However, just recently the touchscreen quit responding at all (I think after an OS update). The remaining functionality is fine, just no touch. At the moment I don't know if it's hardware or software and I've lost the resources that could have solved this for me.

Question is, has anyone encountered this at all (I couldn't find the exact problem using Search)? If so, is there a flash command line option to make sure the screen hasn't somehow become "permanently" locked? I'm only familiar with the basics of the linux flash tool, so be gentle. ;)

Re: N800 touchscreen unresponsive
 

14 views and no replies? Sheesh. You pikers. :p

Anyway, I've disassembled this thing and lo and behold, as soon as I popped the LCD out of its frame it began working! Now I just need to figure out why it wasn't working IN the frame...

Re: N800 touchscreen unresponsive
 

Could this shed some light on the reduced pressure sensitivity along the right edge of the screen? I am thinking of some mechanical tension on the right side affecting the responsiveness of the touchscreen. How is the screen held in place?

Re: N800 touchscreen unresponsive
 

The LCD squeezes into a rubber gasket lining the perimeter of a frame underneath the faceplate. At the back it rests against ground traces on the backside of the printed circuit board. 5 screws hold this subassembly in place, 1 in each corner and one near top center of the device. The rubber gasket is very firm and holds the LCD well even when it's not fully assembled.

What I'm experiencing is a problem with the top center screw area. If the screw is snug, the touchscreen quits responding. If the screw is loosened it works, but then stops functioning again when the faceplate is snapped on. For reasons I have yet to discover pressure in that region is interfering with touchscreen functionality.

Since I can't determine root cause, I am looking for ways to maintain assembly integrity while also reducing pressure in the critical region. This is more for my own education (and to gain one more working device from the leftovers) than anything else.

NOTE: this is a very early build, the first trial run in fact, and is 2 main iterations behind currently produced devices... therefore what I experience is not necessarily something most purchasers will encounter. That's one thing I was wanting to verify. While it's possible this could be related to the right-side reduced function issue, I am inclined to believe that problem has more to do with hardware specific to that side, such as the LED emitter subassembly.

Re: N800 touchscreen unresponsive
 

Ok, I need to elaborate a little more:

The LCD is in a partial metal enclosure that snaps shut, which in turn sets into the frame I mentioned. Further troubleshooting has led me to see that simply squeezing the top and left edges of that enclosure with my fingers kills the touchscreen response. Applying such pressure to the right and bottom sections has no apparent effect.

So my next step is to remove the LCD from its partial enclosure. YIKES. I really wish at this point I had found a simpler workaround... :eek:

EDIT: ok, the more I look at this the more convinced I am that this is a defective touchscreen. I completely removed the thing from its thin metal enclosure (not an easy task) and squeezing the core component on the left side induces the response failure. At this point there is nothing else for it to contact but itself.

Somehow I have to figure a way to minimize the pressure on the final assembly. Might have to tamper with the faceplate a bit... anyway, bottom line is you guys shouldn't see this, and I'm even more sure that it's not related to the right-side sensitivity issue.

On a related note, I now know EXACTLY what's causing the LED shadowing, and I am vindicated in suggesting that an improved diffuser (there actually isn't one at all) would fix this completely.

EDIT 2: purposefully deflecting the frame a small amount took the necessary pressure off, and the unit now works with the faceplate attached. Yay! One more salvaged device. :)

Re: N800 touchscreen unresponsive
 

Interesting read. Thanks!

Re: N800 touchscreen unresponsive
 

Are Nokia aware of these issues? I followed your posts about the N800 work going elsewhere from you, but it would be good if your expertise on the N800 was not lost.

Cheers
Rich

Re: N800 touchscreen unresponsive
 

trust me, I communicate EVERYTHING to the necessary channels. That should be obvious by now. ;)

Re: N800 touchscreen unresponsive
 

As many others, I also experience a reduced responsiveness of the screen at the right side. Today I observed that after a few minutes the temperature of the screen becomes much higher on the right side than on the left. Somebody here remarked that the responsiveness definitely depends on the temperature and that the software takes it into account when computing the pressure of taps. Now I wonder whether this is the cause of the problem - in this case firmware could fix this hypothetical design issue.

Re: N800 touchscreen unresponsive
 

I am experiencing some lag in my LCD responsiveness. It doesn't seem to respond to my stylus taps unless I put a little more oomph into my taps. I'm not tapping with the most gentle of touches, I'm doing with a bit of force, but it doesn't seem to respond unless I deform the screen a little. Is this a factory defect?

Thanks.

Re: N800 touchscreen unresponsive
 

The touchsceen on my Nokia N800 didn't work straight out of the box. I exchanged it.