Laptop touchpad is jumpy
July 29, 2013 3:43 PM   Subscribe

I have a new laptop (Acer with Windows 8) and the touchpad will intermittently go all goofy. It'll make the cursor jump around the screen randomly and open windows as if I'm clicking, even if I hold my finger perfectly still on the pad. My question: Is there any chance that a third-party power cord is causing this?

I have a second power cord for work that I bought through Amazon, which specified that it was compatible with my laptop model. It's the same polarity, same output, and the plugs look identical. But I can only get the touchpad to act weird if I'm using the third-party cord.

This is not a "tap-to-click" issue -- the cursor will leap all over the screen, change the size of text or icons as if I'm holding down the ctrl key, and stuff like that -- again, while I'm holding my finger still.

I brought both cords to work today and have been switching them back and forth. Since the problem is intermittent, I can't guarantee that this only happens with the third-party cord -- but so far that's the case. It will sometimes act up with the third-party cord plugged in; it has yet to act up with the Acer cord plugged in.

I've been through customer service and gone through all their recommended steps, from changing the touchpad options up to and including resetting the laptop back to factory default. The next step is to mail the laptop back to them -- it's still under warranty -- but I'd rather not if the cord is somehow the culprit. Plus, if it is the cord's fault, the techs won't be able to find anything wrong.

So: Is there any chance that a third-party cord, which seems totally compatible in every other way, is causing the touchpad to act weird?
posted by Karlos the Jackal to Computers & Internet (8 answers total) 1 user marked this as a favorite
 
I've seen this same thing happen with smartphone screens and weird third party chargers. I don't know the technical term for it, but it's probably because the voltage and amperage don't match up exactly with the voltage and amperage of what it's expecting, and it's doing some weird stuff. My suggestion is to change out the cord.
posted by deezil at 3:58 PM on July 29, 2013 [2 favorites]


My landlady had that same issue with her laptop when she was plugged in to her solar-powered house outlet. I second deezil that it's something to do with the power aspect and I'd ditch the third party cord.
posted by jessamyn at 4:10 PM on July 29, 2013 [1 favorite]


It's actually not what deezil was mentioning, Modern laptops will detect that sort of thing and pop up "improper power supply" on the screen when they POST, but it's even worse.

The touchpads in modern laptops that support "multitouch" do it by creating a high frequency electrical charge within the pad, and detecting capacitance via your skin in certain regions.

Interference in the electrical input fucks with this system. Which is to say, your off brand power brick has bad internal power filtration. Your laptop is getting "dirty" power with lots of static in it rather than just a clean smooth 15-20v DC current it wants. This is caused by the high frequency switching within the power brick not being properly filtered out...

This can cause tiresome problems like the DC-DC board(internal power supply within the laptop) running hotter than normal, trackpad issues, and eventually just premature hardware failure.

I've also had one of these off-brand bricks MELT(!!!), cause a mark on my carpet, and burn the hell out of my hand after working perfectly for months. Like literally, my entire house smelled like burned electronics.

In addition to this, these off-brand bricks often skip government regulatory body required safety measures, like separation between high voltage and low voltage bits inside. Check this out, all that kind of corner cutting and general failure in design happens in these.

Return this crap one if you can, otherwise throw it in a drawer and save it maybe as an absolute emergency spare. Then go on ebay and buy a brand name one for cheap. Make sure to search "OEM" and that it looks exactly the same as the real one in the pics before you buy.
posted by emptythought at 4:31 PM on July 29, 2013 [3 favorites]


i got a laptop recently with W8. i installed ubuntu, and the same thing is happening to me. It's annoying.
posted by jpe at 5:26 PM on July 29, 2013


Any chance you have gotten some water on the touchpad when this happens? My gets a little wonky like you describe when, say, I don't dry my hands well after washing them.
posted by ktkt at 6:41 PM on July 29, 2013


I have a Windows 8 laptop (Fujitsu) with a detachable touch screen and it does this too! It is super annoying. I have reinstalled everything, tried to remove potentially offending drivers - to no avail. I'm use the OEM power brick and OEM everything else.

I have noticed that this happens whether or not I'm actually touching the touchpad, and using the touchpad while it is happening doesn't make a difference. The specific behavior I get is the cursor repeatedly tapping at the far left edge of the screen or back and forth across the middle - both very rapidly. I also get random zooming in.

At this point I have NO IDEA what is causing it, but it basically makes the computer unusable and it is super frustrating.
posted by jeoc at 6:59 PM on July 29, 2013


Aces, all. I had used my deductive skills to narrow it down to the power cord but couldn't figure out why it would have this effect, and so thought I must be missing something. emptythought's explanation clears everything up, and I ordered an official power cord from Acer (who were having a half-off sale) today.

You saved me a lot of hassle and a chunk of change. Thanks!
posted by Karlos the Jackal at 2:39 AM on July 30, 2013


To address the other people in here and for future searchers/posters, some trackpads are just goddamn awful. I've used two revisions of the same series of laptop on several models(one acer, one asus). The trackpad would be by manufacturer A in revision 1, and manufacturer B in revision 2.

Rev A. machine would have an awful shitty unpredictable trackpad no matter what driver tomfoolery i tried stepping forward and back through revisions, the windows default ones without the special control panel, etc. It was just an exercise in "Ok it's crappy this way with these drivers, but it's not doing that other annoying thing. Rev B. would be fine, or fine with the bare bones windows drivers but not the fancy shmancy official ones.

At this point if i bought a new machine and the trackpad was annoying, or was annoying after i installed the software or OS i wanted i'd be returning that thing after a day or two at most of testing and screwing around. A lot of trackpads actually just suck. If i wanted a specific machine i might even go to the manufacturers website and check the driver page to see who was making the pad, because most non-synaptic ones seem to just feel like bad synaptic clones that don't work right at this point. Maybe they have a bunch patents and everyone else is trying to rip them off while skirting them? I'm not sure.

It's just that the OPs specific issue was something that has a history of occurring in more modern touchpads/screens, both in mobile devices and in laptops. The kind of suck you guys are describing is a separate and more terminal design or manufacturing error-based suck

The specific behavior I get is the cursor repeatedly tapping at the far left edge of the screen or back and forth across the middle - both very rapidly. I also get random zooming in.

This sounds like an actual hardware issue, especially the corner thing. I'd return this machine immediately if it was at all possible. It sounds like there's some kind of slight short within the matrix of the trackpad possibly caused by it being mounted incorrectly and it getting "stressed" by being torqued a bit in one corner, or possibly the trackpad unit itself(even if it's the touchpad over the screen) being somehow crimped by the screen frame or internally disfigured.
posted by emptythought at 12:44 PM on July 30, 2013


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