IBM Model M Keystrokes not Registering

[Benjio]

So recently my tech-ed teacher brought in some of his old computer equipment and in it was an IBM Model M (52G9700). The second to bottom row of keys all seem to not work, so from 'Z' down to 'Right Shift' (oddly the left shift still works). I believe there are a few other keys that don't work such as the main 'enter' key (I don't have it with me right now, it is at school). The only physical damage I noticed to the keyboard was the PS2 connector was bent up a bit, which I was able to bend back enough to get it to fit in a port. I noticed that there were a few pins missing on the connector (there were only 4 or 5, out of the usual 6), which it may be designed that way because I didn't notice any broken stubs. I also tried the keyboard in both Windows 7 and Windows 95, having the same problem in both, which leads me to believe its definitely not a software issue. So does anyone know what the problem is? And if the problem is identified is it even fixable? (I realize I'll most likely have to take it apart and have to remove/replace some rivets) Anyway thanks for reading this and for any help you can provide.

[flibberdipper]

For now:

[terrytek]

You're really still use a Model M? Welcome to the family, for I still have one.

 

Back on track, I think it may be that the missing pins cause the keys to not register. Try other keys. Do they work? If not, the PS/2 connector is surely dead.

[Benjio]

You're really still use a Model M? Welcome to the family, for I still have one.

 

Back on track, I think it may be that the missing pins cause the keys to not register. Try other keys. Do they work? If not, the PS/2 connector is surely dead.

Like I said, I haven't really been able to use it yet since I found it this way, and also most of the keys do work, just not the ones I mentioned (mostly the row from z to 'right shift' including a few others). Also it looks like the pins are supposed to be that way, there are no signs that there were any other pins ever there (no holes in the plastic or broken stubs, the plastic seems flush at the bottom of the connector).

[terrytek]

Like I said, I haven't really been able to use it yet since I found it this way, and also most of the keys do work, just not the ones I mentioned (mostly the row from z to 'right shift' including a few others). Also it looks like the pins are supposed to be that way, there are no signs that there were any other pins ever there (no holes in the plastic or broken stubs, the plastic seems flush at the bottom of the connector).

 

You mean the stub or the entire housing?

[Benjio]

You mean the stub or the entire housing?

What part of my post are you referring to?

[terrytek]

What part of my post are you referring to?

I was talking about the keyboard PS/2 connector.

[Benjio]

I was talking about the keyboard PS/2 connector.

I'm still not quite sure what you're asking. Like I said, where the pins would normally be, there is no sign that there was ever a pin there, it seems it was designed that way. I just looked up the pin-out of a PS2 connector and it seems that there are two pins which have no purpose, so I assume that is why they are not there. I believe the problem I'm having is probably something to do with the controller or circuit inside the keyboard itself.

[terrytek]

I'm still not quite sure what you're asking. Like I said, where the pins would normally be, there is no sign that there was ever a pin there, it seems it was designed that way. I just looked up the pin-out of a PS2 connector and it seems that there are two pins which have no purpose, so I assume that is why they are not there. I believe the problem I'm having is probably something to do with the controller or circuit inside the keyboard itself.

 

Yeah, it may be that the connector may have been shorted in one of those pins, cutting off communication with those keys.

[Benjio]

Yeah, it may be that the connector may have been shorted in one of those pins, cutting off communication with those keys.

We're still talking about the PS2 connector right? If so, there's only one data pin in the connector, so if that was the problem I'd assume that none of the keystrokes would register.

[terrytek]

We're still talking about the PS2 connector right? If so, there's only one data pin in the connector, so if that was the problem I'd assume that none of the keystrokes would register.

Yeah, we're still talking about the connector. Yeah, I think it may be the problem, since it only has one data pin, since all of the keystrokes can't share one pin. BTW, how can you only have one data pin out of 4/5 other pins?

[Benjio]

Yeah, we're still talking about the connector. Yeah, I think it may be the problem, since it only has one data pin, since all of the keystrokes can't share one pin. BTW, how can you only have one data pin out of 4/5 other pins?

There's ground, power, and clock (not quite sure what the clock's for) as well.

 

[terrytek]

There's ground, power, and clock (not quite sure what the clock's for) as well.

 

 

I probably have 2 theories.

 

1. You bought a flawed KB. If you had a legit PS/2 KB, it would have 6 pins, none removed.

 

2. The previous owner, if there was one, damaged the pins on the PS/2 connector on the KB, rendering the bottom row of keys unusable.

[Benjio]

I probably have 2 theories.

 

1. You bought a flawed KB. If you had a legit PS/2 KB, it would have 6 pins, none removed.

 

2. The previous owner, if there was one, damaged the pins on the PS/2 connector on the KB, rendering the bottom row of keys unusable.

If you read my post you'd know that its not my keyboard, but rather my tech-ed teacher's. I am almost positive the connector isn't the issue, if the missing pins were an issue I doubt it would work at all (they are clearly not needed anyway based on the pin-out). It is an older keyboard (from the mid 90s I think) so I guess maybe things weren't quite as standard back then (such as including all 6 pins). I believe the problem is most likely due to either a bad connection (an internal one) or some sort of short in internals of the board.

[terrytek]

If you read my post you'd know that its not my keyboard, but rather my tech-ed teacher's. I am almost positive the connector isn't the issue, if the missing pins were an issue I doubt it would work at all (they are clearly not needed anyway based on the pin-out). It is an older keyboard (from the mid 90s I think) so I guess maybe things weren't quite as standard back then (such as including all 6 pins). I believe the problem is most likely due to either a bad connection (an internal one) or some sort of short in internals of the board.

Yeah, maybe it may be a bad connection due to the lack of standardization back in the '90s. That's the reason why I ditched PS/2 and went with USB. You don't have to deal with all of the issues PS/2 offered. 

[Benjio]

Yeah, maybe it may be a bad connection due to the lack of standardization back in the '90s. That's the reason why I ditched PS/2 and went with USB. You don't have to deal with all of the issues PS/2 offered. 

I don't think you're quite understanding this, but the PS2 connection is not the issue.

[terrytek]

I don't think you're quite understanding this, but the PS2 connection is not the issue.

 

OK, I really hate to say this, but I give up. My simple and final answer is: The keyboard is old. Like 1992 old. Not wanting to sound rude, but that thing is a piece of junk. Plus, as things get older, they tend to fail more often.

[Benjio]

OK, I really hate to say this, but I give up. My simple and final answer is: The keyboard is old. Like 1992 old. Not wanting to sound rude, but that thing is a piece of junk. Plus, as things get older, they tend to fail more often.

I'm starting to think that you don't even read my posts, haha, I've already identified what the problem most likely is. Also, I agree it is old, but it is definitely not a piece of junk. I'll take another look at it tomorrow at school and see if I can get it apart to find out what the problem exactly is.

[terrytek]

I'm starting to think that you don't even read my posts, haha, I've already identified what the problem most likely is. Also, I agree it is old, but it is definitely not a piece of junk. I'll take another look at it tomorrow at school and see if I can get it apart to find out what the problem exactly is.

OK, I take back what I said about junk. I even still have a Model M; I'm not even sure if it still works. See what is wrong and report back tomorrow, that is, if it isn't buried.

[Benjio]

OK, I take back what I said about junk. I even still have a Model M; I'm not even sure if it still works. See what is wrong and report back tomorrow, that is, if it isn't buried.

Will do, and I'd love to take that off your hands if you don't want it...  :rolleyes:

[terrytek]

Will do, and I'd love to take that off your hands if you don't want it...  :rolleyes:

How much are you willing to pay? I live in the West Coast, in sunny California. B)

[Benjio]

How much are you willing to pay? I live in the West Coast, in sunny California. B)

Was mostly joking, I'll have my own once I get this one fixed up...  :lol:

[terrytek]

Was mostly joking, I'll have my own once I get this one fixed up...  :lol:

But you said it wasn't even your own.

[Benjio]

But you said it wasn't even your own.

He already told me I could have it, I think he was actually quite entertained by how much enjoyment I got out of it.

[terrytek]

He already told me I could have it, I think he was actually quite entertained by how much enjoyment I got out of it.

 

Why would you want it for?