IBM Model F122 Case Repair: Using A M122 Case

[XMIT]

The PVC plastics used in the Model F122 case are notoriously brittle. They do not stand up to the weight of a ten pound or 4 kilogram keyboard. One false move and the top case is cracked.

F122s are decently rare and finding replacement top cases is quite difficult.

Fortunately, we have an ace in the hole: early model M122 keyboards. Specifically, those with the same two-stage legs and side button release. This mod ends up sacrificing an M122.

The F122s have threaded brass inserts (yay!!!) whereas the M122s have coarser threaded bolts into PVC plastic (boo!) so it is necessary to use the M122's bolts.

The repair procedure is as follows:

1. Using a standard Model M driver, remove the three screws at the rear of the F122. Remove the cable cover and the top case.

2. Using the same driver, remove the five screws at the rear of the M122. Save at least three of these screws.

3. The M122 has additional tabs that will interfere with the F122 internals. It is necessary to remove these. I was able to remove (or possible fold over) the tabs at the specified locations using a pair of lineman's pliers.

IMG_20210522_183729.jpg (316.28 KiB) Viewed 1663 times

4. Re-assemble the F122 using the M122 top case and three M122 bolts.

It will look good as new!

[fohat]

This works. I have done it more than once, and I don't remember there being that many interference points..

I believe that wcass pioneered a similar technique that will work with even a later generation M-122 case.

https://geekhack.org/index.php?topic=45 ... #msg939658

[XMIT]

It looks like wcass caught the same interference points I did.

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I still have a few F122s to sell with cracked cases. I'll be modding them with new top cases from donor boards.

[fohat]

It looks like wcass caught the same interference points I did.

He is using a later-generation shell.

It has been a long time, but I seem to remember that with a 1st-gen case less cutting is required, but my memory is not what it used to be ....