Database Info

[Q] TF AC adapter safety hazard

I'd heard some people mention that they had been getting little electric shocks from the TF while plugged in. I experienced this a few minutes ago with the TF plugged into my dock which was plugged into the charger. I think I found out why...
I got my multimeter out and connected the negative to my house's ground. Then I held the other probe to the shield on the HDMI connector on the TF. This should be chassis ground, the same ground you come into contact with when you touch any of the metal. I measured about 62V between what should be about neutral potential and earth. This is the voltage you feel, since 62V is above the breakdown voltage of skin. Fortunately it doesn't seem to be much current since people aren't getting knocked on their asses.
I also noticed that the plug isn't polarized, so I turned it around and did the same check. Only about 5V this time, safe and consistent with what I'd expect between neutral and ground. When plugged in like this, the wide side (neutral) on mine is on the same edge of the adapter as the "S" in ASUS right above the USB connector.
ASUS should be able to fix this with a modified USA plug adapter that has a polarized (wider neutral) prong. For now, even if you're not getting shocked, plug the adapter in with the "S" lining up with the wider prong on the outlet. That is, if you're plugging it into a standard 3-prong with the round ground prong facing towards the floor, plug it in so that the "ASUS" on the end is upside-down.
pix below.

Interesting finding. We should get this on the issue list for Asus to take a look at.

Interesting. Thanks for finding this. It sounds like the power supplies should be recalled or at least a polarized plug sent to all US owners before someone gets hurt. I hope someone at Asus is listening.
One question though. Shouldn't the difference between ground and the neutral be zero?

jerrykur said:
One question though. Shouldn't the difference between ground and the neutral be zero?
Click to expand...
Click to collapse
Not zero, but probably less than 5V. The same circuit measures about 700mV between neutral and ground. I don't know what it means, but at least it isn't a shock.

Mine actually melted. I bought a new one. A dynex ultimate charger dx-ua. Its 11 volts / 1.5 amp. It charges great and no more problems
Sent from my Transformer TF101 using XDA Premium App

This would explain why sometimes I feel the tingling and other times I don't - probably based on the way I have it plugged in.
@D_Czap - Melting is a pretty scary and dangerous possibility...wonder if they're going to issue a recall.

Interesting find! Were you able to take a measurement with the charger plugged into the keyboard, and the tablet charging from the keyboard?

Popsiclestand said:
This would explain why sometimes I feel the tingling and other times I don't - probably based on the way I have it plugged in.
@D_Czap - Melting is a pretty scary and dangerous possibility...wonder if they're going to issue a recall.
Click to expand...
Click to collapse
Hah. I felt that tingling too. Now it makes sense.
Not pleased that my tablet has another issue though

D_Czap said:
Mine actually melted. I bought a new one. A dynex ultimate charger dx-ua. Its 11 volts / 1.5 amp. It charges great and no more problems
Sent from my Transformer TF101 using XDA Premium App
Click to expand...
Click to collapse
If it melted, it was a fire hazard. Be sure to let Asus know!

I noticed the tingling the other day!
Sent from my Transformer TF101 using XDA Premium App

thanks for OP, we can now avoid the tingling by plugging the ac adapter upside down, or in other words with the "S" in the word "ASUS" logo on the side of the longer slot.

klau1 said:
thanks for OP, we can now avoid the tingling by plugging the ac adapter upside down, or in other words with the "S" in the word "ASUS" logo on the side of the longer slot.
Click to expand...
Click to collapse
Reversed the adapter... tingling is gone... this is starting to sound like a jock-itch commercial! LOL Thanks for the tip.
Sent from my Transformer TF101 using XDA Premium App

Thanks to the OP for reporting this issue. I suspect, though, that the problem goes deeper than just a question of polarization of the AC wall connection.
I would expect complete isolation between the AC input and the DC output to the TF. The presence of a measurable AC voltage between those points implies to me that there is some leakage current between the primary and secondary leads of the transformer in the power supply. That just should not be happening.
I suggest that you do a resistance check between the AC connectors (not plugged into the wall, of course) and the chassis ground of the TF when the charger is plugged into the TF. Any resistance reading lower than open would indicate a path for current, and a potentially hazardous condition.
There is another thread on this forum reporting a problem that ASUS is aware of with one model (0B-LF) of the chargers, but I don't know what the problem is, and perhaps this is it.
It would be helpful for anyone experiencing even a mild shock, to check the model number, and post that fact and the charger model number on this thread.
I'm due to get my TF tomorrow, and that's the first thing I will be checking.

As a possibly related aside, I think that Asus is shipping the adapter disassembled for a reason. I think that they got UL approval on the adapter alone, and not the assembled unit. That's easier for manufactures to do these days, just one thing to get approved. That's why they can't ship with the AC portion attached. On the down side, it might mean that the adapter was never tested by UL with the AC prongs attached.

Here is a pic of my adapter with a melted prong, Kind of scary.

After some tests, I am finding that the adapter is marginal at best and should probably not be used to charge the TF mated with the KBD especially when both batteries are low. I have had good results charging separately and in stages stopping when the adapter gets hot. I would not let my combo sit on charge overnight( unattended). I am guessing that ASUS bought the charger from a supplier and that the capacities are overstated making the demand on it too much.

D_Czap said:
Here is a pic of my adapter with a melted prong, Kind of scary.
Click to expand...
Click to collapse
That is indeed scary. Can you provide the model number of the charger?

vicw said:
That is indeed scary. Can you provide the model number of the charger?
Click to expand...
Click to collapse
The model number is AD827M. That was kind of hard to read.

Rumbleweed said:
After some tests, I am finding that the adapter is marginal at best and should probably not be used to charge the TF mated with the KBD especially when both batteries are low. I have had good results charging separately and in stages stopping when the adapter gets hot. I would not let my combo sit on charge overnight( unattended). I am guessing that ASUS bought the charger from a supplier and that the capacities are overstated making the demand on it too much.
Click to expand...
Click to collapse
This could be true. It might be like the Apple iPhone charger recall. Maybe we need to look for chargers with the green dot.

D_Czap said:
The model number is AD827M. That was kind of hard to read.
Click to expand...
Click to collapse
Can you read the 'Type' code (it's on the line underneath the model number) and tell us that too please?

[Q] Nexus S Touchscreen not responding while charging

Hi everyone.
My Nexus S touchscreen has stopped working while charging. The charger is original, and I havent had any problems before this. The screen does work when charge it through my computer. Anyone have any idea what the problem might be? I updated to 2.3.4 around two week ago, but I've charged the phone after the update without the touchscreen dying.

I read about that problem a good number of times now, most often with third-party chargers, though. It seems, that the touch screen is very susceptible to interference on the power source (which is not really surprising, considering the touch sensor technology).
Maybe your wall adapter is just faulty or out of spec.
Something I just thought of: Do you have any power line communication devices? If so, try to unplug all of them and test again.
Try a few different power outlets, too, maybe even in different buildings.

If its not a real charger it won't work. Alot of these phones only will work with OEM charges from Samsung or Motorola chargers
Sent from my Nexus S using XDA App

I would love to know what you mean by "real charger".

One of my chargers is very slightly over voltage (5.2V) and my touchscreen becomes erratic when I use it - I try to keep using it to a bare minimum. Personally I'd stop using that charger. You never know what long term damage it may be causing.

I really don't mean to challenge your measurement, more so since I don't know how you got it, but I find it anything but trivial to measure voltages to any degree of accuracy.
Since I can't afford laboratory equipment with accuracy in the ppm range, I am stuck with a cheap hand multimeter that is rated at 1% plus a few counts, but only inside one year from manufacture when stored the whole time in defined conditions. The next best thing would have been a 150 Euro version with about 0.5%. That means, that the least significant number in the reading is all but useless.
And we are not even talking about ripple, interference and forward leakage. Try measuring your charger's +5V and 0V to earth. You will probably see significant readings.
Anyway, what I am trying to say is: The average user will have to trust the rating on the label.
And the 5.2V you measured are still inside the specification range, which is 5V plus minus 5%, so from 4.75V to 5.25V, if I remember correctly.
If I felt adventurous and had the problem I might try decoupling everything a bit with some big ultralowESR capacitors near the phone. That should give a lowpass together with the cable resistance.

Hi guys,
I have also come across this behavior - I was charging my Nexus S using the supplied USB cable and the screen hasn't been responding nearly at all.
In my case, this was caused by the notebook charger - when I unplugged it (ran on battery), everything was fine again. Therefore I blame my charger to be a source of some sort of interference.
If you are on a laptop, maybe you could try that. If this is a case of the outlet charger, maybe it is not working properly (to be replaced?)
Hope this helps

same here... wt*
okay im using some Chinese charger but what is doing with the display ...

Touchscreen issues when charging

Anyone having issues with your touch screen when you are using it while it's chArging? Just wondering if i have a faulty device or are there others with the same problem
Sent from my HTC One X using xda premium

No my device does not have this issue when charging. I think this issue has something to do with the charger.

That's a grounding problem, had it with my SGSII try a different cable.

The sensation had an issue of touchscreen problems while charging. i went through 3 phones. The cause is the same cause as the wifi errors that people are having with the HOX. Bad connection from unibody(sensation) to board.. If we added aluminum foil or solder (just like the HOX wifi issue) it would fix the problem. On the sensation the problem got really bad to where you couldnt unlock the phone with the lockring. grounding issue. I hope the HOX isnt having that same issue and you just have a bum phone or better yet a bum cord or charger. let us know if its either

yeah happened alot on my s2, was due to usb cable or something
but works fine when im charging

It was the grounding issue, does this damage the phone? I have a wall outlet with USB ports so it might emit too much power
Sent from my HTC One X using xda premium

slojko said:
It was the grounding issue, does this damage the phone? I have a wall outlet with USB ports so it might emit too much power
Sent from my HTC One X using xda premium
Click to expand...
Click to collapse
Every time this has happened it has been because of what the USB cable was plugged in to and not the cable itself. Try the charger it came with in a regular plug. If it doesn't work better then it is a phone problem.

This happens to me too. Charging from the laptop with an eBay (chinese) cable causes the touchscreen to be unresponsive.
Here's how to test: Open the Notes and draw a few lines very fast.
Here's the results:
USB Charging
No USB Charging

Here is a video of it happening to me on my skyrocket. It was because of the charger. Try a different cable, then a different wall adapter.
http://www.youtube.com/watch?v=x__jdlGXyjk

It is because of the charger...it's always recommended to use the charger that came with the phone eventhough they give us a tiny a$$ USB cable.
Sent from my HTC One XL using Tapatalk 2

Yes, I have an issue - when the phone gets to 90%+ while charging, the screen becomes very unresponsive. The drags don't drag - instead the touches are registered as taps.
You can get an app like MultiTouch Test - and you will see, it's very clear to see when this happens.
My first One X device did not have this issue, so it's something specific to my current unit. Doesn't bother me much, since it only happens at 90%+ charge, while plugged in...

neocryte said:
My first One X device did not have this issue, so it's something specific to my current unit. Doesn't bother me much, since it only happens at 90%+ charge, while plugged in...
Click to expand...
Click to collapse
To me it doesn't happen all the time, sometimes it happens, sometimes it doesn't. Unplugging the cable and plugging it back in seems to temporarily fix the problem, if I leave it charging for a couple more minutes, I think the problem will come back, but again, unplugging/plugging it back, solves it temporarily. It's weird...
Oh, and all this to say that I observed this behavior while charging around 65%, not 90%. And I've only observed this while charging with AC power with the original cable and charger. The problem did not present itself (yet) while charging through USB.

Touchscreen While Charging
Nazgulled said:
To me it doesn't happen all the time, sometimes it happens, sometimes it doesn't. Unplugging the cable and plugging it back in seems to temporarily fix the problem, if I leave it charging for a couple more minutes, I think the problem will come back, but again, unplugging/plugging it back, solves it temporarily. It's weird...
Oh, and all this to say that I observed this behavior while charging around 65%, not 90%. And I've only observed this while charging with AC power with the original cable and charger. The problem did not present itself (yet) while charging through USB.
Click to expand...
Click to collapse
I just had this happen with the stock charger from my old HTC One using it on my HTC One X. Along with touchscreen problems it got VERY hot located as you are looking at the camera side it got hot on the top right side near the camera. Dunno what that could be. Both chargers are rated at the same voltage and amperage, I dont get it
jmdwyer

jmdwyer said:
I just had this happen with the stock charger from my old HTC One using it on my HTC One X. Along with touchscreen problems it got VERY hot located as you are looking at the camera side it got hot on the top right side near the camera. Dunno what that could be. Both chargers are rated at the same voltage and amperage, I dont get it
jmdwyer
Click to expand...
Click to collapse
It's caused by electrical noise. The voltage supplied from your mains outlet is alternating current (typically 50/60hz in frequency). a usb charger has to do two things; firstly step down the voltage (110v/230v/240v down to 5v) and secondly rectify the alternating current into direct current (positive and negative). how it does this is by using a transformer which employs an iron core surrounded by copper windings, this generates a lot of rf (radio) which travels down the cables to the device as well as broadcasting a short distance through the air, a decent charger will use shielding as well as a few other pieces of circuitry which will neutralize the rf given off. In order to rectify the voltage the charger will use a variety of diodes and capitors, in a cheap Chinese charger they will typically use as little as 2 and possibly a generic chemical capacitor (similar to a small battery) these degrade over time and can get quite hot, fat and eventually burst - when you hear about chargers exploding or setting on fire it's usually because the capitors aren't up to the job. a Chinese charger may have all the quality control and certification stamps but most of them are forged, if you buy a charger for less than $10 this is what your likely to end up with. the outputted voltage may appear 5v on a multimeter but they are a very dirty output and can spike from 3v to 7v or even more the load on the charger increases. The dirty output interferes with the mechanism used on touch screen devices which also employ a type of capacitance to register where you are pressing on the screen. A decent charger will use solid state capitors and which should last a lifetime.
if the smartphone miss behaves whilst charging 90% of the time it's because of a faulty charging device (or one employing poor components). a decent charger may cost more $20 but they are significantly safer for both you and the device.
The problem with mains sockets with built in usb usually comes down to shielding, they will either have none or be earthed (which might sound like a good idea but in practise a lot of domestic devices will create leakage to earth causing more noise - alot of studio equipment will have a separate earth). These may not be as dangerous as cheap Chinese chargers but still undesirable.
If a original or good quality charger isn't available one of the best sources for charging a phone will actually be a desktop pc with a usb3 port. The whole pc is insulated in a nice metal case and there are a plefora of high quality components to create a stable clean power supply (a cpu voltage tolerance is usually measured to 2 decimal places of a volt which is pretty good).
Ditch the rubbish cheap chargers, you honestly get what you pay for and they aren't good for the long term health of the phone. If it hums or makes a high pitch noise whilst plugged in your playing with fire - literally. they aren't bothered if your phone dies in 6 months or bursts into flames so long as they get the $5 x 100,000 people who buy them (these things literally cost pennies for them to put together, even though the case might look the business inside they are nasty and as cheap as)
Sent from my HTC One XL using Tapatalk

Very insightful. The worst part is that I have two original HTC chargers and they both emit the high pitched noise.
Sent from my Evita

timmaaa said:
Very insightful. The worst part is that I have two original HTC chargers and they both emit the high pitched noise.
Sent from my Evita
Click to expand...
Click to collapse
Some of the very small chargers might whistle a little, its called coil noise and isn't as bad as capacitors about to pop. The iron core hasn't been sufficiently dampened or glued into the case so it resonates when the ac passes through it, the pitch may change depending on the voltage (whether its a 230v or 110v power supply). It isn't unsafe but HTC should be doing a better job at checking the new chargers, over time most chargers will develop coil noise as glue tends to melt or degrade.
Very insightful video, you'll never buy a cheap charger again
https://www.youtube.com/watch?v=wi-b9k-0KfE&feature=youtube_gdata_player
The gist being the cheap chargers could very well set on fire and the USB could go live at mains voltage with no circuit protection, death traps spring to mind. Be careful what you buy.
Sent from my K701HBC using Tapatalk

[Q] How does wireless charging works?

This might look like a stupid question. But I really wanted to know how is a phone charged without a wire connection. I mean you need to pass electrons while charging right? There must be a layer of air(No matter how slight) in-between the charger and the device which has a resistance of about 10^13 to 10^16 ohms. So how does the electrons passes through this layer?

Induction

Krazhil said:
Induction
Click to expand...
Click to collapse
Thanks. I just got it. The process is something like an electric transformer. Just one part of it is on the charger side, and the other is inside the Cell phone. So ain't we wasting a lot of power through the process. I mean efficiency is never 100%, is it?

I believe the wasted power is related to the coil's material (the less resistive, the less dissipated power).
So yes, efficiency could never be 100% because there's no material with 0 resistivity.

Slazur said:
So yes, efficiency could never be 100% because there's no material with 0 resistivity.
Click to expand...
Click to collapse
I mentioned compared with the wired charger. It's wastage r8? And it's not really wireless(got a cable between the charger and wall socket) so what's the point?

I can't recall correctly, but there will be a little bit more of wasted power compared to wired charging (due to the air's permeability to let the electromagnetic field produced by the coil "flow")
Well yes, it's still wired, but the joke is to not plug the phone.
Personally, I always charge my phone on the same spot when I'm home, so it certainly could come in handy.

Slazur said:
Well yes, it's still wired, but the joke is to not plug the phone.
Personally, I always charge my phone on the same spot when I'm home, so it certainly could come in handy.
Click to expand...
Click to collapse
So you are keeping the charger plugged into the wall socket all the time? If not than I still didn't get the point why if yes you are wasting a lots of energy of over the day. I thought we are looking for an energy efficient world. I'm I wrong?
I do support if it's built inside a cars dashboard or something like that. Just to put the phone on your dashboard and it's charging. But in case of home still wired is better. Though if it was something like wifi that could work from a distance would make a good point. You know what I mean....

Do you hear noise from the Huawei Mate 9 charger when it is NOT charging?

I got the phone for awhile,
the phone itself is running very well.
but i have another concern,
i start to hear the super charger when it is idle (not charging but plugged into the wall)
when it is charging, it is completely silence.
Do you also hear the noise from the charger too?

Can't say I have noticed that. But I always turn chargers off when not in use. It's safer.

I sit close to one at night, in total silence, and I can't say I've ever heard any noise coming from it.
Sent from my MHA-L29 using XDA Labs

Yeah, I heard it too. I have two chargers and both do the noise.

What kind of a noise? Like a humming sound? Electrical buzzing?
Sent from my MHA-L29 using XDA Labs

Better call them Ghost Buster folks.
On a more serious note, never experienced anything like it. Turn off your charger when you're not using. Better charger life longevity.

This has been a thing with LG chargers for years. For some reason they just hum or buzz.

I wouldn't worry about longevity tbh. Any good quality charger will largely outlast the device it hooks to. Heck my 1995 Motorola Flare charger still works.
If the buzzing gets on your nerves you can always get one of those cheap socket adapters with an on/off switch (see attached).
Sent from my MHA-L29 using XDA Labs

I used to get that on my old Samsung chargers. Never heard anything with my mate 9 charger tho. I wouldn't worry about it if I were you.

Thank you for the input for using a switch to turn it off when not using...
but the most important point is, i have a friend who also own a Mate 9, his charger is dead silence when charging or idle.
The sound is more or less like buzz (but very little sound)

rayraymond said:
Thank you for the input for using a switch to turn it off when not using...
but the most important point is, i have a friend who also own a Mate 9, his charger is dead silence when charging or idle.
The sound is more or less like buzz (but very little sound)
Click to expand...
Click to collapse
I can confirm your charger noises. Wired thing. Better unplug the charger, because noise means it is burning up energy!

Not to be dumb but is it your outlet? Have you tried a different one? Mine is completely silent

rayraymond said:
I got the phone for awhile,
the phone itself is running very well.
but i have another concern,
i start to hear the super charger when it is idle (not charging but plugged into the wall)
when it is charging, it is completely silence.
Do you also hear the noise from the charger too?
Click to expand...
Click to collapse
Notice this as well one night while reading on the phone in bed. Mine does it with or without charging. I've also experienced this with a Sony adapter, and Samsung. I have a few devices plugged into a 8 prong switched grounded outlet... I just flip the switch off in the morning and this this actually lasts until bedtime??

rayraymond said:
I got the phone for awhile,
the phone itself is running very well.
but i have another concern,
i start to hear the super charger when it is idle (not charging but plugged into the wall)
when it is charging, it is completely silence.
Do you also hear the noise from the charger too?
Click to expand...
Click to collapse
Phone chargers are step-down switching power supplies.
They are called switching power supplies, because electrical current flowing into coils or capacitors is always switched on and off to get a desired amount of electrical energy saved inside this energy storages to get lower voltage than the power line. They are verry efficient and much smaller than conventional ones.
Because of the current switching the plates of the capacitor or the windings of the coil can vibrate and cause this sounds.
It depends on the components if there is a sound or not and can vary from batch to batch.
So no worry if the supply creates silent noise, its working fully, only different components are used! (as long as it is no super cheap china power supply, they could be very dangerous)
And i think the power supply lives as long as the phone. Computer or TV power supplys are always plugged in too and they have the same technology.
But i always unplug the power supply to save enegy