IBM Model M2 spring-compatibility

feltel · 08 Nov 2018, 17:49

Hello there,
with a little bit of luck and a spelling error I was able to aquire an IBM Model M2 for an reasonable price. The seller described it as working with one ore two stuck keys. Upon receiving it I checked it (removed keycaps using a wire key puller) and unfortunately I discovered some serious bent spings. Some springs were stretched and the spring and hammer for the left ALT key is missing at all. So I came to the conclusion that someone tried repairing it and failed.

The keyboard also suffers from dried capacitors, but this should not be a problem replacing it.

I know and own Model Ms for decades and know how to remove keycaps without damaging the springs.

Before I go any further in disassembling the M2 I'd like to ask if the springs and hammers are compatible with those from a regular Model M. I have some new Unicomp-made ones in my spares box and it would be cool if I could use those springs to repair the M2.

Muirium · 08 Nov 2018, 17:59

I think they’re different. What with M2’s lower profile caps, and so shorter buckling spring housings. Could be worth an experiment, though. But M2s are a bugger to open up and put back together, as I remember.

digital_matthew · 08 Nov 2018, 18:09

I've used Model M springs in M2s with no problems. I haven't tried replacing the hammers, but I think they are interchangeable. Muirium's right, they are a pain to open and close. Be prepared to break a few of the plastic teeth in the process; that's just part of the fun.

Findecanor · 08 Nov 2018, 18:22

The real fun (not really...) is when you break plastic teeth that hold the controller board to the case, and it is no longer able to hold a connection with the membrane ...

BTW. I have long wondered if it would be possible to bolt-mod one of these. I have not seen anyone do it, and I am not bothered enough to do it myself.

clickykeyboards · 08 Nov 2018, 19:10

The buckling-spring and hammer assemblies in the Model M and the Model M2 are the same and they are interchangeable.

feltel · 08 Nov 2018, 19:13

Thankyou. After close inspection I counted 10 bent or streched springs and one missing.

Nice summary (not). Tomorrow I'll source some replacement capacitors and hopefully the M2 is in working order really soon.

feltel · 08 Nov 2018, 20:03

I got it apart without breaking any clips. Indeed the springs and hammers are the same. The black one is from the M2, the white one I bought from Unicomp as a Model M replacement part.

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digital_matthew · 08 Nov 2018, 21:24

Findecanor wrote: The real fun (not really...) is when you break plastic teeth that hold the controller board to the case, and it is no longer able to hold a connection with the membrane ...

Yep, I don't even remove the PCB when replacing the capacitors for that very reason. Reassembly is a pain too. You'll have to be a lot more careful when replacing the keycaps than you would on a Model M. Also be careful not to break the plastic stabilizers. If you end up ruining some springs you can always use the chopstick method to replace them so you don't have to take it apart again. Good luck!

Findecanor · 08 Nov 2018, 23:38

digital_matthew wrote: Reassembly is a pain too. You'll have to be a lot more careful when replacing the keycaps than you would on a Model M.

Oh yes, I had achieved springs broken as in the image in the top post, and had to open it up again because I did not know about the chopstick method ...

OldIsNew · 09 Nov 2018, 02:47

Findecanor wrote:
digital_matthew wrote: Reassembly is a pain too. You'll have to be a lot more careful when replacing the keycaps than you would on a Model M.
Oh yes, I had achieved springs broken as in the image in the top post, and had to open it up again because I did not know about the chopstick method ...

It's so true.

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The chopstick can save much of this.

feltel · 09 Nov 2018, 10:54

I managed to reassemble the Keyboard without causing any damage. *hooray* There are only two or three minor issues I don't know atm how to repair. If not pressed carefully enough the (bigass) enter key does not come back to the initial position. It stucks in the pressed condition. The keyboard did it also pre-repair.

All in all the stabilisators of the M2 are shitty crap. Those tiny tiny plastic-ones are easy to break if not carefully handled. The only metal wire stabilisator is under the (bigass) enter key. The other issue I'm facing is the somewhat slow repeat rate of some keys. I have not checked it in detail but it seems some keys have an faster repeat rate than other.

But I'm happy to have purchased the keyboard after all to complete my Model M keyboard collection.

digital_matthew · 09 Nov 2018, 15:55

For your Enter key, try taking a slightly dampened cotton swab and clean out the inside of its barrel. That's helped me with stuck keys in the past. Also you may need a new spring. The key repeat inconsistency may be a problem with the traces on the membrane. At any rate, congratulations on the functional M2! An underrated keyboard IMHO