Thinkpads Forum

Does anyone feel electricity from right palmrest??
and does anyone have a solution for this?
Thank you.

Static, so ground yourself. The palmrest is plastic, and it will not conduct electricty except if wet. Further, what is under the palmrest is 5 volt stuff and other than the UltraNav, it doesn't touch the palmrest. So I would be very certain you are getting static shocks. ... JD Hurst

jdhurst wrote:Static, so ground yourself. The palmrest is plastic, and it will not conduct electricty except if wet. Further, what is under the palmrest is 5 volt stuff and other than the UltraNav, it doesn't touch the palmrest. So I would be very certain you are getting static shocks. ... JD Hurst

Thank you for your reply...
but I think I got schock from fingerprint sensor(?)...
I am not quite sure.
when I remove my foot from groud, I don't feel any electricity.

chung1q wrote:Does anyone feel electricity from right palmrest??
and does anyone have a solution for this?
Thank you.

Could be Lenovo's experimental Personal Area Networking technology. It uses your skin to store/transfer data. Very useful, but you just have to be careful not to touch anyone you don't trust with your private information from now on...

[quote="astro"]Could be Lenovo's experimental Personal Area Networking technology. It uses your skin to store/transfer data. Very useful, but you just have to be careful not to touch anyone you don't trust with your private information from now on...



LMAO

... Getting shocked from the fingerprint reader does sound plausible to me, though...

GoofyG28 wrote:

astro wrote:Could be Lenovo's experimental Personal Area Networking technology. It uses your skin to store/transfer data. Very useful, but you just have to be careful not to touch anyone you don't trust with your private information from now on...



LMAO

... Getting shocked from the fingerprint reader does sound plausible to me, though...

And I thought it was just me....

ok, very funny..!

and when he sweats, does he sweat bits or bytes..?

IMO, reality is it is HIGHLY unlikely that this user is experiencing anything other than static..
and that is unlikely too..
at least in any significant strength..

that said if he is in an extremely dry environment and has wool carpeting (or nylon, i forget) and he is prone to shuffling along (thus dragging his feet) a buildup of static might occur and the thinkpad might be discharging his charge..

Its probably static from the touchpad.

It could be that your laptop is floating wrt ground and hence may be at 115/230V depending upon where you are. While the current flow is very low, it is a bit un-nerving, as I found with my TV, which seems to be floating at 230V (here in UK) unless grounded by something connected to it. Often a system will float to mid voltage, unless a resistor or auxilary device provides a link to ground.

As for static, as we have a lot of static build up at home, it concerns me that I get a static shock when swiping the fingerprint reader. At times of high static, I try and touch something like a radiator beforehand to take static to ground.

Try a different power adapter. If you have one with three wires, be sure that ground is connected properly. As Nick Y mentions, it can be floating. E.g. in some very old houses, where there is no ground wiring, if only two of the three wires are plugged in (one should not do that), one might be able to feel some current flow when sliding the back of a hand on the LCD screen (very lightly touching) -- it feels like a little sticky and vibrates a little (somewhat similar to the fan's vibration).

I ask this as someone with a limited understanding of EE so be gentle, but if the US power supply lacks a ground wire, why do the international power supplies need one? Also, since AC power never enters the laptop, how could the grounding of the AC/DC brick affect the laptop? Wouldn't the AC generated for the backlight inverter be imune to grounding issues at the brick as well since it's generated anew from DC current?

-darren

BillMorrow wrote: that said if he is in an extremely dry environment and has wool carpeting (or nylon, i forget) and he is prone to shuffling along (thus dragging his feet) a buildup of static might occur and the thinkpad might be discharging his charge..

Uh... excuse me while I shuffle over to ....oops, just got shocked, to install the new 1GB ram module. Smiling with the self satisfaction of doing the job (myself). Oh wait... (booting up, checking the bios) the ram is not recognized, shuffle shuffle, oops forgot to ground myself. What ram?

*taken from the BOFH handbook*

"Before giving a RAM update to a user's machine, be sure to "zero" the RAM by running it up and down the carpet tiles two or ten times....This will help remove any residual memories of previous programs the RAM may have had and prevent actual crashing of any of the user's programs.



Joking aside; I have gotten shocks before. There are certainly clothing combos to avoid like the plague when working with computers. Such as large sweater turtlenecks made out of wool plus rubber shoes. You can get some pretty significant shocks from that; even through the Fingerprint Reader.

HTH

If the OP was talking about a brief static shock, that is one thing. If he is talking about a persistent buzzing sensation, then that is something entirely different.

As a previous poster noted the AC from the wall never enters the machine. But the inverter for the backlight produces high voltage AC, and it could be leaking enough to give a decent shock.

If he is really feeling an electric current from his machine he needs to stop using it NOW and call Lenovo to get it fixed. This is a serious safety issue.

And before people object that the inverter output is very low current - people have been killed by less under adverse conditions. It really doesn't take much to stop the heart if you get the juice flowing through the chest the wrong way.

Ed Gibbs

darrenf wrote:if the US power supply lacks a ground wire, why do the international power supplies need one?

My guess is that European regulations require three wires if power consumption is above a certain value. Or maybe one is allowed to use it in a wider range of environments if it has a ground wire. I would assume that EU regulations are more strict because the voltage is 230 V compared to 115 V in the US (which also means better insulation would be required for 230 V while the copper wires themselves can be thinner).

Also, since AC power never enters the laptop, how could the grounding of the AC/DC brick affect the laptop?

Quality of isolation of the power adapter?

a) The 'third' wire is a protective device.

b) Why does the 'dc 0V' float way from 0V if there is isolation between AC and DC sides -i.e. via (non-auto) transformer when there is no connection to tie the DC 0V to ground? Leakage and cross coupling via stray capacitance. (Try -carefully- connecting AC voltmeter between antenna connector and ground on many TV's.) As a youngster I once got a nasty shock when I was playing around with / mending a TV. I was touching the chassis and I leant back and touched a radiator with my other hand. (Later, post Uni, we had a chap at work who was aligning CRTs and he told me that he always worked on them with one hand in his pocket; very sensible, esp. with EHT for CRTs.)

Old TV's were different in that they had higher voltages, generally did not use transformers to isolate the mains AC, and used the metal chassis as TV ground. Most of them had polarized plugs and you could have a dangerous situation if not maintained properly and plugged in the right way.

An IBM ThinkPad is very different in that, in my experience, the DC voltage out of the power brick is isolated from the mains AC. I never say "never", but I have not seen a situation where there is any external voltage on the ThinkPad ground system. (I do have the equipment to check).

The recent recalls of power adapters (IBM ThinkPad i was an early one) were related to fire safety IIRC, not electrical grounding safety. ... JD Hurst

chung1q wrote:Thank you for your reply...
but I think I got schock from fingerprint sensor(?)...
I am not quite sure.
when I remove my foot from groud, I don't feel any electricity.

Do you get a continuous shock, or just a quick one-time shock? If you touch it right away again (without moving yourself or the laptop), do you get shocked again?

I've had this shock before, I know what you're talking about. It's not too frequent though, so I don't think there's current leaking from the power supply into the fingerprint reader. I'm agreeing with everyone else that it's probably just static shock.

After I bought a surge master, I didn't get any shock.
Thank you for all replies!

Do you get a continuous shock, or just a quick one-time shock? If you touch it right away again (without moving yourself or the laptop), do you get shocked again?