07-13-2011 09:54 PM
Nice find! I can confirm this jumpy effect is due to the power supply grounding as the wiki article mentions.
I also have the slim 90W adapter and it is unusable when it is connected. To test this effect, I plug in a USB cable to a port on the machine and hold onto the metal part on the other end of the cable using one hand and moving the cursor with the other. THE JUMPY ISSUE IS GONE when I do this so it has something to do with grounding.
I'm suspecting a recall of the adapters will have to be done.
07-14-2011 07:29 AM - edited 07-14-2011 07:29 AM
It's indeed a great find- if the grounding is the sole problem is there a power adapter which works with the X220 and doesn't lead to a jumpy touchpad?
Also: An official update from you guys at Lenovo would be great - cause I think about returning my X220 if there won't be a fix for this within the next month..
07-18-2011 11:06 AM
I just ordered an X220 and the slim 90W adapter. However, the P/N listed on the order for the adapter is 41R4493, not 41R4538 as was mentioned by Mark_Lenovo. It was the one recommended as an accessory when checking out. I guess we should add that variable to the list of inquiries made of Lenovo engineering. I won't recieve my order until mid-August so hopefully things will be sorted out by then.
BTW, since all of these small power adapters incorporate switching regulators, this phenonenon is probably due to the fact that there can be significant noise on a switching regulator when it is lightly loaded. At least, that well-known issue fits these symptoms. Many switching power supplies specify a minimum load as well as a maximum load.
08-06-2011 12:54 AM
I am also confiming the problem. I have an ultraslim 90watt adapter, and see the exact same issue.
and It's first time that experience like this problem. I used use this ultraslim adapter with X200s, W500, T400s, X300, X301, T60, T61p and even T42(with 16v tip) and I've never experienced like this touchpad jumping.
I have other normal 90W adapter in my house.. I'll check with this normal 90w adapter and will post.
08-06-2011 07:17 AM
I checked this with normal 90w adapter, and I found that it's touchpad worked properly.
and on 65w adapter it's OK too.
Touchpad jumpy occur only when it plugged with ultraslim adapter (FRU 41R4493, exact AC adapter FRU 41R4510)
I'm not sure whether it's OK or not when it plug with it's auto(airplane) adapter. but I'll check it too.
and when it jump, trackpoint work properly.
08-08-2011 12:40 AM
08-08-2011 05:39 AM
Engineering perhaps ought to try recreating the situation anywhere outside of the lab. Perhaps some conditions within the lab are properly grounding the touchpad and preventing this from happening?
Seemingly everyone who's tried this with an UltraSlim outside of the lab has experienced the problem. It's impossible to miss, as the touchpad is literally unusable.