A good spec Pentium II computer
arrived on the bench the other day. The owner, after plugging
in a PS2 keyboard, could no longer use either the keyboard or
the mouse port.
There's a warning in Windows, seen
if you start up a computer without a mouse to the effect that
you must switch off your machine if you need to plug in a PS2
mouse. The PS2 connector carries 5 volts and because the pins
are pretty tiny and the connector locating method is fairly flimsy,
a short can result if you insert a keyboard or mouse plug the
wrong way round. The result is a blown fuse or burnt track on
the motherboard together with potential other damage.
In this case we tried an old USB keyboard
with a PS2 mouse socket fitted to the rear. This worked until
we attempted to fit a new keyboard when things started to go
wrong. Eventually the motherboard wouldn't boot up because the
BIOS EPROM seemed to have developed a fault and later testing
of the 32 Mbyte memory DIMM showed this to have expired also.
All was not lost however, a new motherboard,
a faster, more modern processor and a new DIMM saved the day!
The cost of these was a better bet than finding a new motherboard
into which to install the old working bits.
Be warned. Plugging a PS2 device into
a box with a mains plug attached doesn't always result in a catastrophic
fault but when it does it can be quite painful on the pocket.
On the other hand, looking at it philosophically, it's a good
excuse for upgrading!