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Unisys PW2 300 (80286, 10mhz) Keyboard controller failure

G

grastukker

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Dec 5, 2013
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8
Hello everyone,


I'm Jeroen, I am 28 years old and I live in Hengelo, a little town in holland, near the german border.

I have an old Unisys pw2 computer and would like to know more about it.
My uncle gave me this computer in the late 90's and it still worked, untill a neighbor came by with a keyboard and would like to know if it still worked.
I plugged it in the Unisys, and started it. The keyboard wire was getting a bit warm(not hot) so i turned it off immediately. From that moment, the computer didn't work anymore (I know, it was a stupid action, but I was twelve at the time and didn't had any expirience then).
It still started, but did not respond on it's original keyboard anymore.
It gave the following report:

keyboard failure
keyboard controller failure

0,64k Base Memory, 00000k Extended
Gate A20 failure
Decreasing available memory

Does anybody know how to get this old Unisys back to live?
I searched the interned with this failure and think that the keyboard controller chip might possibly be dead ?¿?
The specs from the Chip are: Intel P8042AH 2219
3911-9037

On the edge of the Mainboard stands: PW2 300 CPU BOARD

I appreciate every information with regard to this old machine, also its age, etc etc.
 
The last url doesnt work.. Better reupload it to an image server.
 
Well, I guess as expected a Gate A20 error also seems to be a bad keyboard controller. Does it by chance use a card for the keyboard controller or is that built in to the motherboard? You might have to start looking for blown capacitors, etc at this point.
 
barythrin said:
Well, I guess as expected a Gate A20 error also seems to be a bad keyboard controller. Does it by chance use a card for the keyboard controller or is that built in to the motherboard? You might have to start looking for blown capacitors, etc at this point.
Click to expand...

The keyboard controller is build in to the motherboard. I already started the computer without the keyboard controller chip on the board, and it didn't made any difference, stil the same report. Can it be that it's not the keyboard controller chip that died, but other parts that are damaged?
The keyboard controller chip is a P8042AH from intel
 
I made some photo's today.

The keyboard controller chip:

051220132831_zps919ea206.jpg



Motherboard type:

031220132781_zps8cb92e98.jpg



And the place where the keyboardcontroller houses:

061220132861_zps402cbffe.jpg


061220132871_zpsb4187e71.jpg


061220132871_zpsf7d40d04.jpg
 
I figured out something else. I got two different startup screens. one without keyboard plugged in, and then the computer is counting it's memory like it used to do:

061220132941_zps56407001.jpg



And the screen that I get when I startup the computer with keyboard plugged in:

061220132931_zps1a438013.jpg



So it seems that the keyboard still has some influence on the startup of the computer. How can this be explained?
 
Last edited:
Robin4 said:
The last url doesnt work.. Better reupload it to an image server.
Click to expand...

thanks, I noticed it to late. (I already posted a responce, but it seems that I can't get new replies on this topic? even if I reply myself, it's still not placed in my topic, what did I do wrong?)
 
I don't mean to bump an old thread, but did you ever figure this out?

I grew up with that same model of computer, and couldn't help but ask.
 
yes, I called Unisys Netherlands, where an old engineer told me what the problem could be.
He told me about a green(as green as a frog) fuse that looks like a tiny capacitor. on one of the photo's you can see what i mean. The engineer told me, that if you have a short circuit in your keyboard, that little green fuse is the first thing that will blow up. I meassured resistance, and yes, it was dead! The local electronics shop here in hengelo(TessaTronic) had those old green fuses still in stock, so i bought one, exchanged it with the dead one(soldered) and it was alive after many years!!! it responds on the keyboard!! thank you Unisys netherlands! The only thing that I still need is Bios-software, cause my battery was also empty and replaced that also. but i don't have the original bios software. Does anybody know how I can get this software?
 
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