"Paul" wrote in message
...
Jo-Anne wrote:
Using WinXP and Contour USB optical mouse. Today, several times the
cursor didn't move when I moved the mouse; then it would start up again.
Finally, Windows informed me that a USB device was malfunctioning and I
should try another port or another device. I plugged in another mouse,
and it's working fine. The Contour mouse is expensive to replace (around
$110), so it's a good thing I had an extra one in my office. My question:
Are optical mice fixable, or should I just toss it?

Thank you!

Jo-Anne

As a "broken wire specialist" :-) I would remove the screws
from the mouse, and examine the condition of the wires where they
connect to the mouse PCB. Sometimes the broken wire, is in
an insulated section of the wire (like where the wire passes
through the mouse casing).

To repair broken wires, you undo the "knot" in the wire, which
functions as strain relief, cut about three inches of wire off the end,
strip and prep the wire ends and connect them to the mouse PCB. This
procedure can be repeated until the wire is quite short. Replace the
knot as well, so the mouse continues to have strain relief. Some
mice have plastic posts, and a torturous path the wire feeds
through, which performs the same function as a knot in the wire.
The strain relief, prevents exterior stress, from getting to
pull the wires away from the PCB.

(This is almost as much fun, as fixing the wiring in a Weed Wacker.
Which I have also done.)

Take note of the wire colors, and make a diagram of wire color
versus which hole in the PCB they go into.

Occasionally, an optical mouse has a failure in the optical sensor.
I have no idea how you diagnose things at that level of detail.
As I'm a "broken wire specialist".

The sensor is actually more complicated than you'd think. I think
it has a matrix of detection elements. And the sensor chip may
do some kind of analysis to determine movement. It's more than
a simple photodetector. When you look inside, you'll see a
plastic lens assembly, over top of the sensor chip.

http://en.wikipedia.org/wiki/Optical_mouse

"Optical mice capture one thousand successive images or more per
second. Depending on how fast the mouse is moving, each image will
be offset from the previous one by a fraction of a pixel or as many
as several pixels. Optical mice mathematically process these images
using cross correlation to calculate how much each successive image
is offset from the previous one.

An optical mouse might use an image sensor having an 18 × 18 pixel
array of monochromatic pixels. Its sensor would normally share the
same ASIC as that used for storing and processing the images. One
refinement would be accelerating the correlation process by using
information from previous motions, and another refinement would be
preventing deadbands when moving slowly by adding interpolation or
frame-skipping."

It can probably still function, with dirt on the lens. But a
completely dead sensor, is a completely dead sensor.

Check your wires first. Using an ohmmeter, you can buzz from
USB connector to the pad on the PCB, and prove each wire on the
mouse is intact. It can be difficult to detect a wire which
is intermittent, and get it to open circuit at the same time
as you're measuring it.

The idea is, if you're lucky, removing the screws and doing
a visual inspection, tells you all you need to know. If you're
really lucky, the wire will visually tell you, the break is
inside a certain section. But sometimes, you just have to
"give it a trim" and snip off the three inches of wire and
re-terminate.

And it's pretty hard to repair something like this, without
tools such as your "trusty" soldering iron. The burn mark on
my finger is just about healed now. I only lost a little bit
of nerve sensitivity.

HTH,
Paul


Thank you, Paul! My husband is the wire repairperson in our household. He
managed to fix our old hair dryer when one wire broke, and now he's about to
fix the other wire. So I'll definitely give him this post.

Jo-Anne