Keyboard only partially functioning

[fenix]

I need some expert advice. I was asked to fix a not input problem or no delete problem in MS word and it turned out to be that the normal keyboard keys do not work. It has a ps/2 connection. I tried another ps/2 keyboard and got the same results. The special keys work for predetermined shortcuts like OE, IE, My documents, but nothing else works, including page up, down, scroll arrows or numbers no matter if number lock is on or off. (It does light and unlight the num lock indicator led).

OK, some more info: when a letter is depressed, you hear a small scratchy sound coming from the computer. While trying different things, sometimes the scratchy sound kept clicking until the number lock key is depressed. It's almost like the keys are somehow turned off. I did a windows update and uninstalled the drivers a few times with no help. It always found new hardware and asked for a reboot, and no change.

I was hoping that using a usb keyboard would use a different circuit other than the built in keyboard controller, but after trying a new MS wireless keyboard and mouse, same result. Special functions work but not the normal keys. And I get that little scratch sound each time a key is depressed.

Sooooo...my questions are: Is the keyboard controller shot ?
Is it repairable, or worth it or is it time for a new computer (2002 P4, xp home, gateway 2 gb) So until I'm told otherwise, I'll assume that using a usb keyboard uses the same keyboard controller on the mobo since going usb didn't help. A geek squad guy at Best buy told me that it would be a work around, but that proved to be incorrect in this situation.

The owner of the computer is an exceptionally active typist and many letters are worn off from heavy usage. Did she just wear out her keyboard controller ? She is kind of nervous because she has many projects in the works that are time sensitive.

One last note on the new wireless keyboard that I tried: pressing the number lock did not change the middle led light on the usb receiver like it does on my computer (same one)

Thanks in advance for some highly needed advice.
Sorry for the length of this post but I think I covered it all.

fenix

 

[wahnula]

Hopefully you have researched Sticky Keys and Toggle Keys and eliminated them as a possibility.

My take is that bench time is expensive, a new socket 478 mainboard is not. Since the customer seems to be mainly using the PC as a word processor cut your losses, change out the MB and if you're lucky you can find one with a duplicate chipset that will allow you to just drop in the HDD and go, worst case you will have to do an in-place restore of the OS and be done with this. You can spend HOURS chasing a problem like this, unless one of our esteemed colleagues goes "AHA!" and types in a brilliant solution. I am a pragmatist.

Tony

 

[fenix]

addendum, I do get the 3 lights that blink on and off (except number lock stays on) during POST.

Could a good cleanout of keyboard controller with compressed air be a fix ? I didn't get to open the case yet but they do have a cat.

 

[fenix]

Thanks for the reply.

I'm all for the AHA scenario and I understand your point.

Just for my own knowledge though, does a usb keyboard use the same keyboard controller that the PS/2 keyboard does ?
I'll be digging in my Mueller's.

Rebuilding the mobo and OS etc would probably take
second seat to helping her get a new computer and setting it up for her. That would probably be more desirable to them also. (2 little 90 year old nice sweedish ladies who are ex teachers...sharp as a whip).

 

[fenix]

From what I have read, the chipset architecture of the 478
uses looks like it has the keyboard and mouse controllers integrated in the super I/O chip in parallel with the flash rom firmware hub. I guess usb or ps/2 is just the path to the same place, so in this case it seems the mobo needs replacing.