IBM Model M13 -- 1KRO?

[Phaedrus2129]

This keyboard appears incapable of registering left arrow and right arrow at the same time. Hold down one and the other won't register. Huh??



Left arrow conflicts with:
right arrow
a
s
d
f
j
k
l
;
numpad 1
numpad 2
numpad 3
numpad -



I'm confused.



There are other combinations that don't work, but left arrow is the worst. Is the membrane borked?

[Phaedrus2129]

Contacting the seller, going to see about a refund.

[WhiteRice]

Why would you need to use both the left and right arrow at the same time?

[TexasFlood]

This keyboard appears incapable of registering left arrow and right arrow at the same time. Hold down one and the other won't register. Huh??



Left arrow conflicts with:
right arrow
a
s
d
f
j
k
l
;
numpad 1
numpad 2
numpad 3
numpad -



I'm confused.



There are other combinations that don't work, but left arrow is the worst. Is the membrane borked?

Working fine here.  ALL those combos.

Maxiswitch M13 through a Blue Cube into USB.

Contacting the seller, going to see about a refund.

So the individual keys work, it's just a level of rollover issue?  I really don't know what the rollover on these things should be, but reading a bit of the start of the N-key rollover test, seems that testing shows IBM Model M results from 2-4 key rollover results.  I didn't read anywhere near the whole thread.  Not sure what causes the variation.  Is it broken or just somehow different.  Be interesting to see if the seller offers to refund it.  Playing devils advocate, if the keys work and nothing more was promised, then...  But I guess it depends more on the attitude of the seller than anything.

[TexasFlood]

This keyboard appears incapable of registering left arrow and right arrow at the same time. Hold down one and the other won't register. Huh??



Left arrow conflicts with:
right arrow
a
s
d
f
j
k
l
;
numpad 1
numpad 2
numpad 3
numpad -



I'm confused.



There are other combinations that don't work, but left arrow is the worst. Is the membrane borked?

Working fine here.  ALL those combos.

Maxiswitch M13 through a Blue Cube into USB.

Contacting the seller, going to see about a refund.

So the individual keys work, it's just a level of rollover issue?  I really don't know what the rollover on these things should be, but reading a bit of the start of the N-key rollover test, seems that testing shows IBM Model M results from 2-4 key rollover results.  I didn't read anywhere near the whole thread.  Not sure what causes the variation.  Is it broken or just somehow different.  Be interesting to see if the seller offers to refund it.  Playing devils advocate, if the keys work and nothing more was promised, then...  But I guess it depends more on the attitude of the seller than anything.  Going to have to test mine.  Also I just saw in in the Testing section of the WIKI "Do I need N-key rollover?" page, "For the IBM Model M (and most Cherry models about 1998 and later), GH will block 4567, RTZU (RTYU), VBNM as well as F and J. TZ (TY) and BN are equally problematic."  So sounds like there are some combos that block rollover.  Wonder if this varies between models as well?

[Phaedrus2129]

Why would you need to use both the left and right arrow at the same time?

Movement in some games. Arrows and the A/S keys are very important for some games; I noticed it first during Cave Story.


A broken membrane is something that impairs basic functionality of the keyboard; I think I have at least some case if I have to take it to eBay problem resolution.

[TexasFlood]

Movement in some games. Arrows and the A/S keys are very important for some games; I noticed it first during Cave Story.


A broken membrane is something that impairs basic functionality of the keyboard; I think I have at least some case if I have to take it to eBay problem resolution.

I'm honestly not sure if you have a real case or not.  But if you make it sound plausible and are insistent, you might win anyway.  I see it all the time, :wink:.

[Phaedrus2129]

Directly into PS/2, which is working fine since it reports 2KRO/NKRO on all my other boards.

I think there's a dead trace or two on the membrane, or something screwy with the controller. Only thing that makes sense.

[Rajagra]

Another reason why non-NKRO boards suck. No fault tolerance.

Non-NKRO means some combinations of 3 keys will fail. If one key is stuck down then that's a whole bunch of 2-key combos that are going to become unusable.

[Phaedrus2129]

I was going to do a bolt mod anyway (practice for my 1391401 which really needs it). Can you fix a trace on a Model M with one of those little circuit pen things?

[TexasFlood]

Another reason why non-NKRO boards suck. No fault tolerance.

Non-NKRO means some combinations of 3 keys will fail. If one key is stuck down then that's a whole bunch of 2-key combos that are going to become unusable.

If that is the case, won't running a test program and testing all the keys reveal it?  If a key is stuck, I'd think that you would have a strong case for a refund.

[Rajagra]

If that is the case, won't running a test program and testing all the keys reveal it?

Maybe not, since the key was 'pressed' before the keyboard initialised, the controller might not recognise that it is down. Worth checking though.

[Phaedrus2129]

Maybe not, since the key was 'pressed' before the keyboard initialised, the controller might not recognise that it is down. Worth checking though.

Just tried that with a different board, the held key registers. Then, this is USB...

[TexasFlood]

Maybe not, since the key was 'pressed' before the keyboard initialised, the controller might not recognise that it is down. Worth checking though.

Maybe I'm not following or don't understand.  But if the key is pressed then you shouldn't be able to press it again and have it test good should you?  Not sure that that is how it seems to me.

[Rajagra]

OK, simple test I just did. Press A. Keep it down. Press S. Release S, keeping A down. (Now you've stopped A from auto repeating.)

(This approximates the state your keyboard would be in if A was stuck down from the moment it was powered up.)

Launch Aqua's Keytest or similar. It shows no keys are being pressed.

[TexasFlood]

OK, simple test I just did. Press A. Keep it down. Press S. Release S, keeping A down. (Now you've stopped A from auto repeating.)

Launch Aqua's Keytest or similar. It shows no keys are being pressed.

Now press the already pressed A, Aqua's keytest won't register that either right?  That's what I mean by a keytest should show this condition if it exists.

[Rajagra]

You can't press a key that's already pressed (electrically speaking.)

The problem is the keys you are having trouble with - ones that work on their own but not in pairs - are not the one(s) that are stuck down.

[TexasFlood]

You can't press a key that's already pressed (electrically speaking.)

The problem is the keys you are having trouble with - ones that work on their own but not in pairs - are not the one(s) that are stuck down.

That's my point.  If any key is stuck down, you shouldn't be able to press it so it will fail a test.  Simply test every key and you'll know.  Right?  Or am I missing something?

[Rajagra]

That's my point.  If any key is stuck down, you shouldn't be able to press it so it will fail a test.  Simply test every key and you'll know.  Right?  Or am I missing something?

Ah, see what you mean. You are right.
Unless there is some weird short in a position in the matrix that has no key.

[Phaedrus2129]

Numpad enter key does not register, and using another keyboard with the same matrix causes the same blocked combinations when holding down numpad enter.

Rajagra, if this forum had rep I'd rep you.

[TexasFlood]

Ah, see what you mean. You are right.
Unless there is some weird short in a position in the matrix that has no key.

I thought about that after my last post, but guess you have to figure what are the odds that a trace with no stress on it would spontaneously fail?

[TexasFlood]

Numpad enter key does not register, and using another keyboard with the same matrix causes the same blocked combinations when holding down numpad enter.

Rajagra, if this forum had rep I'd rep you.

Might want to pull that cap, check the spring and reseat.  I've fixed a few malfunctioning bucking spring keys that way, think I had to carefully bend a mangled spring back into shape.

[Phaedrus2129]

Just did that. I'll test it in the morning.

[TexasFlood]

Another reason why non-NKRO boards suck. No fault tolerance.

Non-NKRO means some combinations of 3 keys will fail. If one key is stuck down then that's a whole bunch of 2-key combos that are going to become unusable.

Numpad enter key does not register, and using another keyboard with the same matrix causes the same blocked combinations when holding down numpad enter.

Rajagra, if this forum had rep I'd rep you.

Yup, looks like Rajagra was right.

[TexasFlood]

Just did that. I'll test it in the morning.

So were you able to revolve the issue or no?  My knowledge of bucking spring issues is pretty limited.  I've basically only reseated keys and bent springs back into shape, nothing major like a bolt mod or replacing springs/hammers.

[Phaedrus2129]

Good news and bad news.

Good news: I have 2KRO again.

Bad news: The spring for numpad enter came out when I tried to fix it, and I can't see how to get it back in right now.


The spring was leaning crooked, so I tried to rotate it so it was right, but it just came out of the hammer. That stopped the key from being permanently held down, but now that key is just non-functional.

[TexasFlood]

Good news and bad news.

Good news: I have 2KRO again.

Bad news: The spring for numpad enter came out when I tried to fix it, and I can't see how to get it back in right now.


The spring was leaning crooked, so I tried to rotate it so it was right, but it just came out of the hammer. That stopped the key from being permanently held down, but now that key is just non-functional.

Not perfect, although better than a sharp stick in the eye.  Wonder if the spring can be reinstalled short of taking the whole thing apart?  I'd defer to the more experienced here to comment on that.

[itlnstln]

Ripster has a pic of using a sharpened chopstick to remove/install springs.  Insert the stick in the spring and twist left to remove, twist right to install.

[TexasFlood]

Cool.
Now if I can figure out how to fix a non-working trackpoint button.  The left button on my recently procured M13 doesn't work although the trackpoint and right button are both fine.  I plan to take it apart and see if it's repairable but haven't gotten to it.  Anyone have experience based wisdom to share here?  Am I just scewed? :wink:.  Probably not too late to get a refund but I'd rather fix it if I can.