KenK wrote:

Nope. Didn't work. System said no keyboard found when booting and mouse
pointer was frozen when system started. sigh I was hoping...

OK, next question. Do any of these
subsystems (PS/2 or USB) light up any LEDs ?

Some of the cheaper motherboards, skimp on fuses
for the +5V supply.

A "good design" assigns one Polyfuse per two USB headers.

A "good design" assigns a Polyfuse for the parallel (printer) port (+5V).

And the PS/2 ports may have their own fuse too.

However, some try to run the whole works, off one fuse.

A traditional Polyfuse is green in color, and has
a "notch" in the end of it. These examples might
be rated for 1.4 amps (for two USB ports of 500mA each).
The green-ness, and the notch, help them stand out
when inspecting a PCB.

http://i.imgur.com/GuxsJ.png

*******

A Polyfuse is a polycrystalline device. The active
material "melts" if too much current is drawn.
When the power is off again, the material cools
off and goes back to crystal form (where the crystal
conducts electricity).

This means that normally the fuse resets itself.
There is nothing to replace (normally).

You can check your ports with a multimeter, but
this is difficult to do without some deal of care
so you don't short something out while working on it.
An easier check, is to check fpr +5V on either side
of the fuse, while the keyboard is connected, proving
the fuse is still closed.

A USB device with a LED on it, like a USB reading lamp,
a device that has no "USB state" but just draws power
from VCC, is a good means to verify power is present.

I suspect you may have a power problem, and the above
is a hint about what to look for.

A failed Polyfuse doesn't normally burn to a crisp,
so you won't likely get a hint that way. You could
ohm it out, with your multimeter, as it should have
a decently low resistance across the terminals when
cold. I'd do it with all power off on the PC, just
to make the results more predictable.

(There is a capacitor on the output side of the fuse,
which provides holdup of the +5V rail voltage against
inrush current. USB peripherals are only allowed to
use capacitors around 1/10th the size, so that when
a USB device is plugged in, the rail voltage doesn't
sag too much. So there is electrical circuitry on
either side of the fuse, which could influence a reading.)

Some of this is addressed in this document, written
by Intel to help motherboard designers during
the USB2 era.

https://web.archive.org/web/20060626...therboards.pdf

Anyway, most of that is for fun, and if you can get
any sort of LED to confirm it's got power, that's
good enough at this point.

For example, this USB desk lamp, draws 5V @ 400mA,
just under the 500mA limit for a USB2 port. So this
would be a good test for power availability. A typical
ATX power supply, can only run about five of these,
as the +5VSB rail used on modern designs, has a
2A limit. I don't know if you'd find these at a
Walmart or not.

http://www.mobisun.com/en/mobisun-le...light-usb.html

Paul