Dead Keyboard and Mouse

[Dean]

My kid's PIII boots up okay but the keyboard and mouse
will not do anything.
I have changed them and tried USB and PS2 versions. I've checked
the power supply, keyboard fuse on the MB and everything
else I can think of.

My guess is the motherboard is faulty, it is a Gigabyte GA6VXC-4XP
the only identifiable symptom is that a known good PS2 flashes the LEDs
about once per second.

Does anyone have any ideas before I replace it. I'm happy to replace the
board
but because of supply problems I can't get a socket 370 and
will need to replace CPU and RAM too if I change board types.

I can access my kid's PC across my home network but they can't use
it to do anything(and are drivin' me nuts)

thanks Dean

 

[Gareth Church]

My kid's PIII boots up okay but the keyboard and mouse
will not do anything.
I have changed them and tried USB and PS2 versions. I've checked
the power supply, keyboard fuse on the MB and everything
else I can think of.

My guess is the motherboard is faulty, it is a Gigabyte GA6VXC-4XP
the only identifiable symptom is that a known good PS2 flashes the LEDs
about once per second.

Does anyone have any ideas before I replace it. I'm happy to replace the
board
but because of supply problems I can't get a socket 370 and
will need to replace CPU and RAM too if I change board types.

I can access my kid's PC across my home network but they can't use
it to do anything(and are drivin' me nuts)

Does the keyboard work outside of Windows (can you press Del when you boot
the machine to get into the BIOS)? Normally if there is a problem with the
keyboard the PC will halt and not boot. The fact that both the keyboard and
mouse have gone, and that it occurs for both PS/2 and USB would indicate to
me that it's not a hardware error. It's very possible to a port somehow
(bend the pins or something), but to have both PS/2 ports go and also have
USB not work is too much of a coincidence. If you plug some other device
into the USB port is it recognised? That would rule out USB being faulty.

I have not seen this problem before. If it was just one component I would
suggest you fiddle with the settings to make sure the right keyboard type
etc is set. In this case though I will take the easy way out and suggest
Windows is just shitting it's pants. I would backup any data over the
network then reformat and start again.

Gareth

 

[Dean]

The delete button will not allow access to the bios. The boot just continues
as normal, ignoring the pressing of the delete button.
I was really surprised that the boot continues completely normally
regardless of whether the keyboard and mouse are plugged in or not..
I have checked the pins and even tested all relevant voltages at the
sockets.


I have never encountered a fault like this before and I'm stumped.
It definitely seems like a software problem but for the fact that
I can't access the bios.

I didn't think of trying USB devices other than the keyboard/mouse
and that is a good suggestion. I have a couple of simple things
which will likely give a good indication,

regards Dean

 

[Dean]

Yeah they both work fine on my own PC. They are in the right ports and
I am beginning to think that it must be something around the keyboard fuse.
The block diagram for the MB also shows one chip in common here so
I think it may be fried.

The really odd thing though is the failure to halt the boot process,
this is something the MB has always done and now it starts fine
with nothing plugged in whatsoever.

Anyway school goes back Monday so I can relax for a while.

regards Dean

 

[rcm]

The system will boot if you "Halt on No errors" or "All but Keyboard" in the
keyboard BIOS settings. This BIOS is feature is there to allow systems to
boot if they are just printer servers, firewalls, etc., that require no
interaction with the user.

I had a dead keyboard fuse once on a 486. I know I shorted it. I posted to
this group years ago and someone told me about the keyboard fuse. On 486,
it was still a visible component, green, looking like a small resistor. It
had leads, ever so small. I was not skilled enough to solder on a small
wire so I just took a wire from a multi-stranded wire and with patience
wrapped it around the posts of each end of the fuse. It worked, system
booted. It worked for years after.

On later motherboards, they are stamped right on so it is impossible to
bypass by a non-skilled person. Too small. I don't know why they even
bother to put it on the board. Maybe to protect components like the
CPU,cards, RAM, etc. Or a legacy design.