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Date: Wed, 7 Feb 1996 11:10:39 -0800
From: ck <ck@be.com>
Subject: Mouse issues

From Joe Palmer, our hardware designer....

I've found a hardware problem on the I/O card that could account for
problems we have seen with some brands of PS/2 mice not working. The Values
of the RFI bypass caps are reversed for the ground and mouse data lines,
which could cause the the rise and fall times for the mouse data signal to
be too slow on some brands of mice.

        If your PS/2 mouse is presently working, no change is required to your
I/O card. A change will be made to the bill of materials to fix this problem on
all future machines.


[Rework Instructions:]

Remove the I/O card:
        Shut down and unplug the power cable
        Unplug any cables connected to the I/O card.
        Loosen the two thumbscrews from the back of the system
        Remove the system cover
        Remove the 3 #6-32 screws holding the I/O card from the machine
        Pull the top of the I/O card away from the rear panel
        Remove the I/O card
        Note the ASSY number of the I/O card.

For cards marked ASSY 830 0002 - 04

        Option 1: Remove C122 from the back of the PCB. This will remove all
                  filtering from the mouse data line, and leave a smaller
                  value cap on the mouse ground.

        Option 2: Swap C124 and C122. This will set the correct values
                  for both Mouse data and Mouse ground.

For cards marked ASSY 830 0002 - 02

        Option 3: Remove C115 from the back of the PCB. This will remove all
                  filtering from the mouse data line, and leave a smaller
                  value cap on the mouse ground.

        Option 2: Swap C115 and C117. This will set the correct values
                  for both Mouse data and Mouse ground.


Replace the I/O card:
        Replace the I/O card
        Replace the 3 #6-32 screws holding the I/O card in the machine
        Replace the system cover
        Tighten the two thumbscrews from the back of the system
        Re-connect any cables that were connected to the I/O card
        Connect the power cable, Power up

________________________________
Joseph Palmer
Director of Hardware Engineering
Be, Incorporated.

C.K. Haun <TR>
The Developer Guy at Be, Inc.



