N9: Touch screen not responding while charging
 

Recently, due to a voltage overload at home, my original charger got damaged. Got a spare one yesterday (iPhone charger it seems; but not original). When I plug in the charger, the touch screen becomes unresponsive and sometimes it asks me whether I want to connect the phone in mass-storage mode or sdk mode or sync and connect :confused: When I unplug the charger, the screen responds as normal :rolleyes:

I couldn't find a thread and/or discussion related to this issue other than this :( Somewhat weird but I am not sure what it is and whether it would damage my device or not :(

Re: N9: Touch screen not responding while charging
 

I occasionally have this issue with my N95 charger and the microusb adapter provded with the N900. I always thought it was that little box emitting some kind of electromagnetic waves that interfere with the digitizer. Maybe the shielding of your charger's cable isn't good enough?

Re: N9: Touch screen not responding while charging
 

That usually happens if you have 3rd party chargers which might generate interference as they sometimes are badly built. Change charger to original or just better built quality charger. And yes it can damage your phone in the long run if you dont change.

I also think there are some electomagnetic waves caused by bad shielding of the charger.
Maybe you can check this by opening the compass-app, plug in your charger and look whats happening. :)

Re: N9: Touch screen not responding while charging
 

Hmm... I haven't tried shielding the cable yet. Will give it a try. And also, thanks for the compass suggestion :) Btw, I am still using the original USB cable with 3rd party charger.

Another weird thing I noticed is that the battery is taking hours to charge these days. Yesterday I plugged in when the battery was almost empty and after 1.5 hours, the charge level was the same. This, I guess is not the issue with the charger as the same thing happened when I plugged in the USB cable onto my laptop. And the battery status in settings shows that the battery condition is good. Also, once I get it charged fully, the battery behaves as normal and gives me 1 day backup.

Re: N9: Touch screen not responding while charging
 

If you use the original cable it should be OK, as the Nokia cable is pretty good quality. Otherwice I would have suggested trying another cable as I have found that micro-USB cables vary a lot in quality. I've got some cables that charge well and some that don't, seems that on some cables the internal resistance is a bit higher which causes a voltage drop ust large enough to affect charging.

Of course it's possible that your cable (or your device) has damaged the contacts or there is just plain dirt so that the resistance grows too high on the connector...

Re: N9: Touch screen not responding while charging
 

just get a new charger, if your using a charger that breaks touch events, then most likely that charger also doesnt charge the battery efficiently, or might even break the battery.

And battery replacement will cost you many times the original nokia charger price, so using broken charger is a wrong way to save money.

Re: N9: Touch screen not responding while charging
 

Just tried connecting the USB cable to my laptop and it charges as usual and the touch doesn't seem to have any issues. The quality of the charger must be the problem... But still needs to figure out why the battery is taking ages to get charged fully :-/

@rainisto: Yes, need to replace the charger soon.

Re: N9: Touch screen not responding while charging
 

Okay, now ith has been resolved: The charger you are using is not following the same USB detection standard as the phone.
What got me confused, was that you told first that charging with laptop works also slowly. This could be caused by the cable, but if laptop charges OK, then the problem is elsewhere;

See, there are at least 2 competing USB charger detection schemes, the one used by Nokia devices and the one used by Apple devices. (dont know about Samsung et al, but I suppose they use the same standard as Nokia, and Apple is the odd man out as usual...)

So, when charging is done between "intelligent" devices that can act as USB hosts or guests, there is a protocol which is used to find out how much current can be supplied/drawn. This is why the laptop charges your device normally, they understand each other.

When the case is a dummy charger adapter, it knows nothing about USB signalling so the device drawing the current must know how much to try to take:

• Nokia devices know this by sensing that the USB data pins are shorted at the chrger end.
• Apple devices know this by sensing that the USB data pins are pulled high/low by 10k resistors.

So, when you use Apple charger with Nokia device, it is confused and cannot know what is in the other end, hence it will enter emergency mode and draw only 100mA of current in order not to damage the device supplying the current.
Same for Apple device connected to Nokia compatible charger.

Re: N9: Touch screen not responding while charging
 

As qwazix and rainisto say. Such effects are reported on the Big Bad Web. It's not an electromagnetic field though that is causing it, but ripples in the voltage coming from the charger. A USB cable with an embedded filter might be able to filter it out but I am not sure such a cable even exists unless it is designed specifically for charging (the filter would interfere with normal data transfer).

You could try imitating the filter by wrapping a few loops of the cable right as it comes out of the charger around some ferromagnetic material (ideally toroid) and see if it makes a difference, but I'm afraid a better option would be investing in a better charger.

Regarding the charging times, this again points in the direction of a new charger. The USB port on your PC can give only up to 500 mA. The original Nokia charger gives about twice as much. There is your charging times doubled right away, but depending on what your phone is doing, the coefficient might be much worse than 2. For example I found that running SSH drains my battery faster than my PC can supplement.