[pengfoong]

I've downloaded multi touch test apps to test my lumia 620 and I noticed a peculiar behavior.

When it is charging, the screen registers up to 4 touch points perfectly.

When it is not charging, the screen will register single touch point just fine.
It is able to register two points correctly most of the time. When I tried 3 points, it is all over the place. 4 touch points is total fail.

The change of behavior is immediate. As soon as i plug in the cable, it registers multi touch perfectly. When I unplug, multi touch goes awry.

I used several multi touch test app to test and they all gives the same result. The first app tells me that my lumia 620 screen can support up to 4 points
TouchTest | Windows Phone Apps+Games Store (United States)
Multi Touch Test | Windows Phone Apps+Games Store (United States)
MultiTouch Test | Windows Phone Apps+Games Store (United States)

Is this behavior normal or I have a defective 620?

[freestaterocker]

I don't know about the 620 specifically, but I would imagine that's a defect of some sort... Normally phones that perform differently when charging vs battery are worse on the charger. There were a few WP7 handsets that users complained were laggy and unresponsive while charging. I would speak to somebody at a Nokia Care Center about that.

And please let me know what they tell you, as I'm looking at the 620 for my mother for her first smart device.

[pengfoong]

I posted the same thing on another forum and another 620 user reported that his 620 can register up to 7 points (until he cannot fit any more of his fingers) without any problems. That means my 620 screen is defective. Sigh.

[ag1986]

I posted the same thing on another forum and another 620 user reported that his 620 can register up to 7 points (until he cannot fit any more of his fingers) without any problems. That means my 620 screen is defective. Sigh.

Not necessarily. This happened on my Lumia 800 and on my Galaxy Nexus as well. It commonly happens because the charger is defective (specifically, because it's not emf damped). Try a new Nokia or other name-brand charger (not BB chargers though, they make my Nexus screen go all kinds of funky).

[pengfoong]

Not necessarily. This happened on my Lumia 800 and on my Galaxy Nexus as well. It commonly happens because the charger is defective (specifically, because it's not emf damped). Try a new Nokia or other name-brand charger (not BB chargers though, they make my Nexus screen go all kinds of funky).

But my problem occurs when it is unplugged. When it is plugged, it works fine.

[Jan Stephen Santos]

Hey pengfoong, have you solved this issue yet? My lumia 620 also have the same problem, It is bought in Abu Dhabi in Axiom Telcom, my problem is that I'm from the Philippines and this was just a gift for me. I can't return it back to the store because the phone is already here in the Philippines. If you already found out the solution, kindly inform me about it. Thank you very much

[TK2011]

Do you have static charge on your body or any object that's touching the phone? Try again while grounding yourself and see if that makes difference. I remember some old phones touch screen behaving a little differently depending on the surface it's resting on.

[Jan Stephen Santos]

Do you have static charge on your body or any object that's touching the phone? Try again while grounding yourself and see if that makes difference. I remember some old phones touch screen behaving a little differently depending on the surface it's resting on.

I think I don't have a static charge because when it is charging, it works very well without delays. I've tried to use clothe, no luck when it is not charging.

[TK2011]

I think I don't have a static charge because when it is charging, it works very well without delays. I've tried to use clothe, no luck when it is not charging.

When it's charging, phone is grounded. Problem is when it's not charging, right? That's why I asked the OP to try again after grounding himself. Using cloth is not grounding yourself. If you have a desktop PC with metal chassis, you can touch it with one hand to ground yourself and get rid of statics.

[Mahdi Ghiasi]

My phone was able to detect up to 10 fingers on the screen.

But now also I have multi touch problems... :(

Check this similar thread: Check your Lumia 620 screen.