Re: PLEASE HELP: Repair of IIE/IIC Mouses

[et472@FreeNet.Carleton.CA (Michael Black)]

"Jason Whorton" (Please Reply To Newsgroup) writes:
> "Quadrajet1" <quadrajet1@aol.com> wrote in message
> 20030921195301.07457.00000767@mb-m27.aol.com">news:20030921195301.07457.00000767@mb-m27.aol.com...
> <<
> Hellllloooooooo!!!!!! What about testing the wires with an
> OHM-Meter. It will find the broken wire just as easily and
> requires no cutting and stretching. Your approches are very
> amateur to say the least and I don't recommend it at all.
>  >>
> 
>   So, to get to the broken wire, you still have to strip back the sheath and
> cut back all the wires.  Okay, I do have a $400 ohm meter, but not everyone
> else has one, and I was merely saying how to find the broken wire without
> one.
> Once you find the bad wire, how are you going to fix it?
> 
> *******************************************
> How do you already know for certain his mouse has broken wires???
> 
You can't be sure but...

The average person is far more likely to be able to replace a wire than
anything else in the mouse.

Wires are a weak point, especially where the enter something.

Since these mice are not serial output (I'm right about that?)
a broken wire is more clear.  Since there are four separate wires
for each of the directions of the mouse (up/down/left/right) the
mouse not working in one axis will translate to a broken wire.
In a serial or PS2 mouse, a broken wire will result in total failure,
or flakey operation along all axis.

There is very little inside the mouse.  Cylinders that are mechanically
coupled to the interruptor wheels, one for up/down the other for left/right.
Likely you will be able to feel if there is a fault (though it might
make sense to ensure that both cylinders are moving freely).  
Two optocouple (which amounts to an LED and a photodiode) with a space
between the two parts for the interruptor wheels, one for up/down
the other for left/right.  And maybe some gate or schmidt triggers
between the optocouplers and the cable for buffering.  Mechanical
things are more likely to fail before electronics, and if those
interruptors are moving freely, then wire is the next likely suspect.

    Michael