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IBM Model F PC/XT disassembly

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Chloe:
I got this earlier this week and I love it. It's lighter than the IBM 5576-A01 and sounds similarly musical with a metallic springy sound to every press. Keycaps are one piece and have no home row locators. Volume-wise it beats the KPT-84 as the loudest keyboard I own. At 2.6kg it's also the heaviest, a kilo more than the A01. At some point I'm going to make an adaptor so that I can actually use it.



This one was assembled 10-01-1985 in the UK, part number 1501105. I took it apart for cleaning and noticed the plastic casing is very thick (weighs around 500g alone) and painted (inside is yellowish).



The bottom part of the case is metal with what looks like cork feet. There was alot of dusty fluff inside. Seeing this made me want to clean it thoroughly, although I really didn't want to take the keyboard assembly apart. It's made up of two metal plates with the buckling spring modules and a layer of foam sandwiched in between.

   

I took it apart anyway, and at many points I almost wished I hadn't. It was also a real pain to put back together.


Disassembly

First I twisted the tabs a little at the top of the upper plate, which is painted a dark olive. There is one tab at the end that needs to be bent away, and a screw lies under the foam covering controller part of the PCB.



The two plates hook together at the bottom so the upper plate has to be slid out. This proved to be very difficult as they are a tight fit and have sharp corners, so be careful.



The upper plate has lots of little rust spots that may need to be treated.



The PCB is flexible and can be removed from the lower plate, which is curved. A 14 pin connector is used for just four wires.

   

Each key has its own module which are stuck to the foam. The foam has degraded, leaving little bits everywhere when handled. Unlike the modules in the A01 the rocker actuators do not stay clipped inside. Bear this in mind when pulling the plates apart as some will fall out and might get damaged if they are trapped in between.



I found the space bar a bit too stiff so I tried taking out the stabilizing bar. Pulling the keycap out so it unhooked from the bar wasn't enough, it still acted like an extra spring underneath. Unfortunately the space bar wobbles too much without it so I put it back.

Removing and replacing springs from the rockers is easy (just twist anti-clockwise) because the point is rounded without flat sides like on Model M and A01 rockers. The spring on A01 is a little shorter.




Reassembly

After pushing the modules into the upper plate I sat the upper plate on a pair of these plastic containers so I could fit the rockers so they sat flat.



With the stabilizer mounted the space bar rocker doesn't sit flat. Check the space bar clicks after placing the plate to make sure the rocker hasn't moved. You can see how the stabilizer fits into the keycap.



The upper plate needs to be slid back into lower plate hooks without disrupting the rockers. I used these small plastic clamps to hold the plates together whilst I tapped the plate into place with a hammer. As you can see the space bar needs to be fitted first. There is no way to hook the stabilizing bar into the keycap later on.

lal:
What a *great* HOWTO and very interesting info. I wouldn't have thought that it's painted. Maybe after all there is a way to paint a beige Model M that does not look like s**t. Really good work, switch kitten :)

Chloe:
Thanks guys. :)

Mercen_505:
I'm still waiting to get my hands on an 84 key AT model F. The sound of the keys chattering as you type on an F is just *unbelievable*.

Chloe:
The date on inner metal plate is 1984. The inside of the case is also stamped 1984. The dirt inside was mainly on upper metal plate, there was loose fluff as well. I think something had spilled but it hadn't reached the rockers or PCB. The PCB was only a little dusty.

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