housetrained wrote:
> PS2 wired [XP so tried USB but not seen]
> John
>
>
> "housetrained" <> wrote in message
> news:4cacc878$0$23538$c3e8da3$ eb.com...
>> have tried another working KB but still Keyboard not working. If this
>> is motherboard anyone know if its a common fault and can it be easily
>> fixed?
>> TIA
>>
>> --
>> John the West Ham fan
>>
>>
>> <><
>>
>>
I think that's going to be a challenge to fix (USB keyboard not seen).
You'd need to clean the USB stack. Normally, that would be
done via Device Manager. If you can't get into the system, it's going
to be pretty hard to work a repair. (My theory is, you've removed
an UpperFilter/LowerFilter registry key for the USB keyboard, and
that is why it doesn't work.) It is possible to take the registry files
to another computer and work on them, but that's out of my league.
I really don't know how many USB entries would be involved and
where to look for all of them.
http://www.usbman.com/Guides/Cleanup...afe%20Mode.htm
There is also a script that uses the Microsoft "devcon" program, to
delete USB entries, and allow the USB stack to be rediscovered. You'd still
need a way to run this, and it probably prompts you anyway, for
permission to proceed. (Perhaps editing the script and removing
the prompt, would fix that.)
(Scroll down to RenewUSB.bat . Note the warning in red letters.)
http://www.robvanderwoude.com/devcon.php
*******
Does the USB keyboard have power ? Do you see any LEDs flash on it ?
That would be reassuring.
It could be, for example, that a fuse is shared by several ports. I
think I've had one motherboard, where several ports used a single
Polyfuse (a cheap motherboard). A Polyfuse is a self-resetting fuse,
which heats up when overloaded (and the material state changes), and
cools off when the overload is removed (and recrystallizes in a couple
minutes). Such a fuse would not normally need to be replaced. But if it
fails entirely (could happen after many cycles), then it might be
depriving several ports of +5V (or +5VSB) power.
(An example of a Polyfuse. I look for the "dimple" on the end. And they're
usually a unique green color.)
http://www.littelfuse.com/data/en/Da..._PTC_1812L.pdf
If I look at my Asus motherboard, I might find one green colored Polyfuse
for PS/2. One for parallel port. One for each 2x5 USB2 header on the
motherboard. One for each USB2 stack-of-two on the back of the computer.
So a motherboard can have a number of those, and they normally don't
cause a problem.
In addition to the fuse, some motherboards use a jumper, to select
+5V or +5VSB as the source of power for a USB port. The latter of those
is used, if you want to "wake on key-press'. Modern motherboards have
changed to running solely from +5VSB, and no longer have the jumper.
A circuit diagram, showing the three pin jumper block and Polyfuse,
is here. When a jumper is installed on the 1x3 block, it either
connects pin 1 to pin 2, or pin 2 to pin 3, thus giving power to the
USB connector. If a person were to pull that jumper off the header,
the USB port would appear to be dead. If the jumper pins were corroded,
wiggling it might be enough to fix it.
http://img2.itsogo.net/Upfile2/2008/...1043554395.jpg
The only reason for checking out the possibility in this case, is it is
suspicious that you've lost PS/2 and USB at the same time.
Do any other USB devices work ? Is it only keyboard that is not working ?
Paul