UNSOLVED
Venue 11 Pro 7140 - touch screen glitches when on AC power
I have had a problem with the 7140 I recently got. I haven't installed anything special on it, and all of its drivers are up to date. I have sent this unit to be repaired, and though the LCD was replaced this problem still exists.
When the 24W USB AC adapter is connected and especially if the battery is not fully charged and is charging, I will have a loss of touch sensing while dragging my finger along the screen. If I am dragging an object then it will often drop. This causes problems in games for instance, but you can see the glitchy behavior even on the Start screen. Just drag from right to left to move the live tiles to the left and it will be choppy. When the AC adapter is disconnected, the touch behavior operates perfectly and smoothly.
Anyone else have this problem? I suspect it is a firmware or driver issue, but if it is only happening on my tablet and not anyone else's then it may be that there is a faulty component other than the LCD panel itself (which was replaced). Thanks!
Zoidborg
21 Posts
1247
1
Posted August 3rd, 2015 15:00
I have been working with Dell technical service on this issue since the replacement, and I was able to isolate that the problem only occurs when the tablet is connected to the micro-USB AC adapter, most usually when the battery is being charged (not fully charged). However I have had the problem happen when the battery was not charging (fully charged) while connected to AC power via the micro-USB adapter.
When the AC adapter is removed, the touch screen works perfectly and without error. When the docking station is connected and the tablet is then on AC power that way, the glitch does not occur. Recently I sent the tablet back to Dell, and they again replaced the LCD screen. This again did NOT fix the problem!
My best guess is that there is some kind of RF or EM interference produced by the power connection only through the micro-USB power adapter on the side of the tablet. The problem happens very predictably and is more pronounced as the tablet heats up a bit. Basically try to use any app that requires you to drag objects across the screen. Games (and in particular timed games) are great ways to reproduce this problem. As you drag the object across the screen, it is like it loses touch with your finger or stylus and briefly drops out, so whatever you are dragging gets dropped on-screen.
You can even see it while scrolling the Start screen; the tiles move side to side perfectly smoothly with my finger on battery, but when the glitch occurs under AC power, the tiles will stutter as I drag them across. Sometimes it will even unintentionally launch an app that happens to be under my finger when the touch screen drops and regains contact repeatedly and randomly.
Is anyone else having this problem? I've had such a long history of problems with the 7130 I originally bought, then this replacement 7140 should have resolved it all but it hasn't. I have never had this much trouble with a Dell device ever. Anyone else's experiences with this issue would be appreciated. Thanks!