Asus X401A, crazy touchpad...and I now know why

[Uranium-235]

I tried ordering another touchpad and it was worse. Suddenly, I turned it on today and it was PERFECT. I realized cause of a recent storm I unplugged the adapter from the wall, I plugged it in, and BAM...goes nuts again. Is this EMI? The touchpad is USB based, with a single ribbon cable with no insulation/shielding. Think I should try aluminum foil wrapped with electrical tape (to you know, keep the motherboard from shorting the hell out-but creating a shield). Or do you think the touchpad chips/circut itself is what is suseptable? Maybe I should try to tape it to the keyboard, keep it directly off the motherboard, though there isn't that much space between the keyboard and motherboard. It can't be the power adapter cause other than this it works PERFECTLY (the computer as a whole)

thoughts?

[goontron]

Re: Asus X401A, crazy touchpad...and I now know why

I tried ordering another touchpad and it was worse. Suddenly, I turned it on today and it was PERFECT. I realized cause of a recent storm I unplugged the adapter from the wall, I plugged it in, and BAM...goes nuts again. Is this EMI? The touchpad is USB based, with a single ribbon cable with no insulation/shielding. Think I should try aluminum foil wrapped with electrical tape (to you know, keep the motherboard from shorting the hell out-but creating a shield). Or do you think the touchpad chips/circut itself is what is suseptable? Maybe I should try to tape it to the keyboard, keep it directly off the motherboard, though there isn't that much space between the keyboard and motherboard. It can't be the power adapter cause other than this it works PERFECTLY (the computer as a whole)

thoughts?

my asuse Eeeeeeeeeeeeeeeeeeeeeee had bad caps in the power brick that would crash the system. crackr' open and see!

[Uranium-235]

Re: Asus X401A, crazy touchpad...and I now know why

I would normally agree with you, but the computer is working perfectly fine otherwise, every component, no crashes, or other oddities

[Uranium-235]

Re: Asus X401A, crazy touchpad...and I now know why

correction. I use a gateway adapter, and lowel and behold the touchpad works just fine. How could bad voltage cause something out of the way like the USB touchpad to bounce around, but everything else work perfectly?

[Uranium-235]

Re: Asus X401A, crazy touchpad...and I now know why

correction of the first correction. I tried my mothers lenovo adapter, it started jumping around again! Why does this old gayway adapter seem to not cause it but my mothers 1 year old lenovo adapter cause it.

this is getting weird, any help? any ideas??

[polytek]

Re: Asus X401A, crazy touchpad...and I now know why

Hi,
i think the cause is the switching frequency that cause the difference between them.

[Th3_uN1Qu3]

Re: Asus X401A, crazy touchpad...and I now know why

Have you checked the three adapters? My bet is that the Gateway adapter which works OK has an earth ground connection (3-prong plug) while the others do not.

Asus are known for skimping on filtering. I've seen a bunch of Asus laptops behave like that, and also some HP/Compaq and an old Sony. That behavior is most likely caused by a ground loop in the touchpad circuit picking up whatever crap that switching brick is putting out. A power brick containing an Y cap, without an earth ground connection, can also make it behave like this, since without an earth ground connected to the secondary ground, the Y cap basically makes the ground of the laptop float at half the line voltage.

[Uranium-235]

Re: Asus X401A, crazy touchpad...and I now know why

Have you checked the three adapters? My bet is that the Gateway adapter which works OK has an earth ground connection (3-prong plug) while the others do not.

Asus are known for skimping on filtering. I've seen a bunch of Asus laptops behave like that, and also some HP/Compaq and an old Sony. That behavior is most likely caused by a ground loop in the touchpad circuit picking up whatever crap that switching brick is putting out. A power brick containing an Y cap, without an earth ground connection, can also make it behave like this, since without an earth ground connected to the secondary ground, the Y cap basically makes the ground of the laptop float at half the line voltage.

opposite! the gateway is 2 prong, the original asus and my mothers lenovo are 3-prong. Noodle that

[Uranium-235]

Re: Asus X401A, crazy touchpad...and I now know why

bump. guys what do you think? this is nuts, right?

[goontron]

Re: Asus X401A, crazy touchpad...and I now know why

its got me stumped... and i have worked on every brand laptop out there. including the elusive OLPC.

[fddizon]

Re: Asus X401A, crazy touchpad...and I now know why

goontron,

does all eee pc you have repaired has these behavior and have same solution?

[goontron]

Re: Asus X401A, crazy touchpad...and I now know why

goontron,

does all eee pc you have repaired has these behavior and have same solution?

no, the laptops i have worked on range from a bad cmos battery to a bad bios flash to a bad screen. there was one that the touchpad wouldn't work on, and was fixed by a cmos wipe, but thats the closest i have came to the OP's issue.
as for the bad charger causing the crash, this one was running as my main netbook for a while after the charger replacement, but then i found an aspire one and traded up.

[mockingbird]

Re: Asus X401A, crazy touchpad...and I now know why

I may not know what I'm talking about, but if the isolated ground adapter works and the two three pronged adapters don't, it could be some feedback from the ground?

[ktmmotocross]

Re: Asus X401A, crazy touchpad...and I now know why

its normal that grounded adapters give bad feedback when u connect it to audio amplifier. thats why they need to be ground isolated.

but i think u have some bad capacitors on power rail

[Uranium-235]

Re: Asus X401A, crazy touchpad...and I now know why

the power rail on the motherboard? cause remember I tried two separate grounded power adapters, with the exact same results

[dj_ricoh]

Re: Asus X401A, crazy touchpad...and I now know why

on dell when you use a cheap made in garage adapter the mouse goes crazy.
if you use a good adapter over 4a orig it works perfect.

[Uranium-235]

Re: Asus X401A, crazy touchpad...and I now know why

heres the kicker. I finally got it to her house today, plugged it in, touchpad behaved normally *sigh*

[khaahk]

Re: Asus X401A, crazy touchpad...and I now know why

If it behaves normally at some other location, then you got to search for the noise maker in your house. This might be some power adapter of some kind of router or something like that. If it works fine with another adapter, then it has got better filters than the original adapter.

[Uranium-235]

Re: Asus X401A, crazy touchpad...and I now know why

it works fine with one other adapter, an 8 year old gateway adapter, but a brand new lenovo and its original, produced the same results, how can that smaller, shitty old worn adapter produce better results?

[dj_ricoh]

Re: Asus X401A, crazy touchpad...and I now know why

because that old adapter got a better quality components inside then the new adapter. 100%