Re: PLEASE HELP: Repair of IIE/IIC Mouses

[mjmahon@aol.com (Michael J. Mahon)]

Phoenyx wrote:

>On Mon, 22 Sep 2003 14:41:12 -0400
>"Bill Garber" <willy4SPAM6pa@comXcast.net> wrote:
>
>> I can find much truth in what you've said, BUT, how do
>> you explain the fact that they don't work on the IIc, and they
>> do work on the IIe mouse card?
>
>Because the wire isn't broken through in many cases, simply
>'stretched' so it's conductivity is altered. I've seen this with PC
>mouses also. In poorer times, I've had to make these emergency wire
>repairs myself. Like many I didn't have another testing method except
>stripping the insulating wrapper and checking the wires. Pulling was
>not my method of choice as broken wires will generally bend at the
>break and many weakened wires can be felt. Due to the size of the
>wires, they can rarely take much metal stress.
>
>As for the IIe, //c working difference, the //c is more sensitive as
>the power outputs on it's ports are probably less than what a card in
>a IIe slot can handle. Plus, the //c mouse and port doubles as the
>joystick port so it's hardware is different.

Probably not the issue.

All mouse sensing circuits are several K-ohm impedance, so
"conductivity" is a very shaky argument.  If there were 100 mA
flowing through one of those wires (and even the +5 v connection
is only for one IC), there could be an argument about imperfect
contact of a broken wire causing the problem, but at high
impedance, the wire will either appear good or bad, possibly
intermittently as the wire is moved.

If you suspect that a mouse that works in only one direction on
a //c has a broken wire, but when you try it on a //e and it works
in both directions--even while wiggling the wire--then it isn't the
wire, it's a compatibility issue.

To prove it, reconnect the wires as you wish, then try again.
Dollars to doughnuts it still won't work on the //c.

I repeat, if the problem were a wire failure problem, you would
expect to see half of the failures in the horizontal direction and
half in the vertical direction.  ;-)

-michael

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