Another Model M thread - Terminal Keyboard Cleaning & Modification

[Tarzan]

I got the MOAK (mother of all keyboards) in the post last week, IBM Model M 122-key, part number 1395660.  It was in quite decent shape, the GH-er I bought it from said he'd given it a once-over before losing interest in the task of making it work with non-terminal systems.



I took it apart from a more thorough cleaning, and apart from some minor crud and fuzz, it was quite clean on the interior of the case.



It has a bit of a different layout than the other Model M's I've seen pics of online, instead of individual key barrels, the front plate has molded tubes for each key/spring assembly.



I wasn't planning to do a full bolt mod, as it appeared the plastic "rivets" were in pretty good shape, but as I cleaned the board innards more and more of the little plastic rivet heads popped off, so I ended up trimming off the rest and drilling it out for the complete overhaul.



Putting it together was a real PITA, there must be some trick to bolting it back together so all the blasted little key hammers stay in their slots.  I ended up backing out all the screws except for the row down the center of the barrel plate, and sloooowly screwing the board together starting at one end.  Once that row was complete I worked out from the middle towards the edges, doing a row at a time.  I'm still not convinced I succeeded, as some of the keys don't "pwing," more of a "thunk," so I'll probably have to re-do it again. 



I've got a few more pics if people are interested, and I'll post more on the topic once I get started on the controller/cable modifier.  My goal is to do an in-case install of a Teensy board, so I can use a mini-to-standard USB cable for connectivity.  I'm hoping I can use the full key set, mapping the F13-F24 row to something useful, and re-doing the 10 keys on the left of the board for document macros.



Anyone done a controller mod on one of these boards?  I've searched all of Soarer's posts I could find, and I did find a set of links to a build where they remapped the board to a 101-key AT layout, but nothing quite like what I'm looking for.  Any tips appreciated!

[Krogenar]

Good luck! It's very rewarding to get one of these monsters back in operation.

[Tarzan]

Good luck! It's very rewarding to get one of these monsters back in operation.

Thanks, Krogenar!

I ran across your background link in my quest for more Model M information.  Are you still planning on a follow-up post about the actual rebuilding steps?  Any recommendations for keeping those key hammers in place when putting the layers back together?   

[SmallFry]

Pop by the IRC sometime, Dfj and Kishy are resident IBM experts.

[Krogenar]

Good luck! It's very rewarding to get one of these monsters back in operation.

Thanks, Krogenar!

I ran across your background link in my quest for more Model M information.  Are you still planning on a follow-up post about the actual rebuilding steps?  Any recommendations for keeping those key hammers in place when putting the layers back together?   

I never took the layers apart on mine, and never messed around with the hammers. I took the PCB and giblets out (intact) and actually put both halves of the case into my dishwasher.

I know that sounds crazy, and in retrospect, it was. One of the halves actually bent very slightly out of shape, but not badly enough that I couldn't get it back together. I had planned to convert it to a more ANSI-style layout (going so far as to buy the keycaps from UNICOMP) but quailed after reading fohat's adventures in taking them apart, and putting them back together. So I'm basically a coward. Oh, and I got used to the funky vertical Enter key before too long, so it wasn't an issue.

Fohat put together a really detailed writeup on the subject. Just do a search of his posts and you'll find it.

From what I recall, keeping the hammers intact (not falling out) can be accomplished by hanging the board across two tall books, so that you can hang it all upside down and not disturb them.

[sleepy916]

It has a bit of a different layout than the other Model M's I've seen pics of online, instead of individual key barrels, the front plate has molded tubes for each key/spring assembl

The Model Ms have the one piece ABS plastic that form the barrels. They don't have the individual barrel like the Model Fs.

Like Krogenar said you would want to just hold the board with the hammers facing down across two posts like tall books. That way, the hammers are in the right place and won't be touched. I've done this with my Model F not a Model M but it should be relatively the same.

[fohat.digs]

You guys are wimps.

Putting the pieces back together is FAR easier on a Model M than a Model F, especially if you are sliding the F together as nature intended.

You need to hold the frame up off the desk, upside-down, with the springs in place, and carefully put the pieces back together. I actually built a rectangular frame from scrap lumber, interior opening just big enough to allow the barrels to hang down, while still supporting the perimeter. Two books of equal size will work, but the plate will tend to slide off if you jostle it.

If you have done the bolt mod, you may want to start with as few as 5-10 bolts, in strategic places, until you get them seated and the first few nuts on. Until the assembly is rigid enough to keep the tiny side tabs of the hammers ("feet") from jumping out of their notches, you are in danger of ending up with a bad key.

I have done this thing quite a few times now, and it is very rare for me to hit it just right the first try, even now. Don't get angry at yourself, just take it apart and do it again. My first few bolt mods required probably 3-5 tries to get it right, now I usually get it on the second try.

The most frustrating and time-consuming part is that you have to install all the key stems to test, and remove them all to re-do it. Trust me, after you try to pull the layers apart without removing the key stems, you won't make that mistake again.

Changing the ISO-style Enter, activating the secret keys, and the other stuff is just a matter of figuring out which barrels get springs and which ones don't. Depending on the mod, you may even have a spring left over. And pay attention to the barrel (called "chimneys" in Unicomp-speak) inserts for the stabilizers on long keys such as Right Shift and numpad Enter.

If you are looking at my Model F guide, you will be pleasantly surprised at how easy the Model M is, in comparison.
 

[sleepy916]

The first time I put back the Model F it took about 20 minutes, I was pushing so hard against the tabs it started to make an indent on it. I eventually figured it out and it is easier now. You need fairly large hands to put everything back together without any help.

[fohat.digs]

The first time I put back the Model F it took about 20 minutes, I was pushing so hard against the tabs it started to make an indent on it. I eventually figured it out and it is easier now. You need fairly large hands to put everything back together without any help.

If you look at my guide, you can see how I do it for the F, now.

It takes 2 fairly stiff side clamps, and one long bar clamp (probably under $20) but one person can do it easily in seconds. The big ones are much harder to put back together than the XT and the AT, but if you plan to do it more than once, it might be worth getting some clamps.

[Tarzan]

The first time I put back the Model F it took about 20 minutes, I was pushing so hard against the tabs it started to make an indent on it. I eventually figured it out and it is easier now. You need fairly large hands to put everything back together without any help.

If you look at my guide, you can see how I do it for the F, now.

It takes 2 fairly stiff side clamps, and one long bar clamp (probably under $20) but one person can do it easily in seconds. The big ones are much harder to put back together than the XT and the AT, but if you plan to do it more than once, it might be worth getting some clamps.

Thanks for the assembly tip, Fohat!  I'm going to pick up some clamps for when I take it apart the next time.  I have the terminal board with the RJ-45 connector, so I can't test the keys until I do the controller mod...   

I see in your guide that you used the Teensy controller on a breadboard for internal installation, is there a guide for activating the additional function keys?  I'm still reading over Soarer's guides to figure out what I need to use - I want to run the cables from the 2x3 connector on the 122-key internal board to the Teensy, and then use the USB extension from Teensy to have a mini-USB port on the back/side of the case.  Is that the preferred option?

I'd like to re-use the existing cable port on the IBM board, but install a USB port in the same location, that may take a bit of hot-gluing and trimming to make that mod.

[fohat.digs]

The Model F has a "U" shaped cable clamp inside, but the M probably does not. A Model M is completely different, which do you have?

I like to use "keyboardtest.exe" because it finds all the keys. You can download it, but be careful, you will get lots of hits on other similar programs.

Soarer gives a list of all the keys in his (outstanding) documents, but trial and error is tedious because you have to take the board completely apart to change springs and put it back together to test it. But once the springs are in the right places and the board is together, you can remap all you want.

Activating the key simply involves adding a spring to an empty barrel, the contacts are already there.

I used wcass's method

http://geekhack.org/index.php?topic=17458.120

post #560 to program the Teensy and it worked great.

[sleepy916]

The first time I put back the Model F it took about 20 minutes, I was pushing so hard against the tabs it started to make an indent on it. I eventually figured it out and it is easier now. You need fairly large hands to put everything back together without any help.

If you look at my guide, you can see how I do it for the F, now.

It takes 2 fairly stiff side clamps, and one long bar clamp (probably under $20) but one person can do it easily in seconds. The big ones are much harder to put back together than the XT and the AT, but if you plan to do it more than once, it might be worth getting some clamps.

I've never tried with the F 122, I imagine you would need clamps then but once I figured out where to put pressure, it is fairly easy with just your hands.