[PLUG-TALK] Hardware Question: Cursor In Constant Motion

[Keith Lofstrom]

On Sun, 28 Oct 2007, Keith Lofstrom wrote:
KL>> What does it do when the machine is booted from a LiveCD (and thus, 
KL>> different software)? I can think of about 6 equally weird explanations,
KL>> but if the problem persists with the LiveCD it is probably hardware.

On Sun, Oct 28, 2007 at 05:39:37PM -0700, Rich Shepard wrote:
RS>   It's even worse. I booted a Knoppix-3.6 cdrom and the cursor would not
RS> move at all. Sat there like a barnacle on a pier.
 
KL>> One common hardware issue with Thinkpads is that the trackpoint gets dirty
KL>> or stuck or wedged. But that usually drives the cursor in one direction,
KL>> and stops. A cleaning usually fixes it.

RS>   With xubuntu, the cursor seems driven to the left edge of the screen. I
RS> took off the rubber cap, blew compressed air around the base, and found no
RS> difference. Is there a way to determine if it's stuck or wedged?
RS>   The keyboard is only a couple of years old; I replaced it when most of the
RS> right side of the old keyboard quit working.

So ... it worked once upon a time (?) with Knoppix 3.6, and does not now,
and worked with an earlier version of Ubuntu, and does not now, and the
keyboard failed once before.   My Thinkpad trackpoint has always worked
with Ubuntu (from versions 3 through 4 at least) so I suspect hardware
or BIOS configuration problems.

First, try looking at the CMOS BIOS settings - perhaps it is not set
the way you expected, and that could indicate that the backup battery
(perhaps a little yellow disk shaped object under the main battery)
has died.  In any case, rewriting the BIOS settings may help the
hardware figure out what to do with the trackpoint signals.

Next, try pulling the keyboard, blowing out any garbage, then reseating
the flex connector.  Sometimes it is a bad connection.

If that doesn't work, the chip that does the keyboard control, on the
laptop main board, may have gone flaky.  You may need a new laptop, and
your old laptop is now your new firewall with builtin text screen and
keybouard and battery backup. 

One fellow that has been helpful for Thinkpad problems is John Callahan
( john at callahan.net or ebay at tpads-plus.com ) near Charlotte in N.C.
He fixes lots of Thinkpads, and knows lots of symptoms and cures.
You may end up sending the unit to him.

But I'm pretty close to stumped here.  The earlier keyboard failure
is worrysome, and the same things that break keyboards also break
trackpoints.  

Keith

-- 
Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs