[Philadelphia, PA] I would like some help with the Model M bolt mod

[Fox]

Hi geekhackers,

I've been using the same IBM Model M 1391401 for over ten years, which I pulled it out of a dumpster in 1998 along with an IBM 5150.

A few months ago, a couple of keys stopped registering. I tried a different cable thinking it might be the problem, but it wasn't. So I took it apart and found that some of the rivets had broken.

I've read through the bolt mod wiki article, but I'm not comfortable doing this for the first time on a board I care about, as silly as that sounds.

What I would appreciate is for someone local who has done it before to help guide me through the process. I would prefer to only replace the broken rivets.

In return, I offer a case of your choice of craft beer. Alternatively, I know my way around motorcycles and can help with a small project (carb rebuild etc).

[alienman82]

removed.

[Fox]

Actual Philly. I do get out to West Chester every month or so for a nonprofit I'm involved with.

[E TwentyNine]

Which keys stopped registering?

[fohat.digs]

So I took it apart and found that some of the rivets had broken.

If all the rivets are broken in the area where the keys are not working, the the plates are probably separating and the pivot plates ("feet") are not pressing the membranes together properly. If it is just a matter of too much gap, you can drill out holes in the rivet shafts (1/16" drill bit works great for 2mm machine screws) and use the screws to tighten it back down.

If they are binding, not registering with the proper feel or sound, or gotten out of their tracks, then you will have to peel the layers apart and put them back together.

If the problem keys are not where all the rivets are missing, then you have another type of problem such as broken traces.
 

[Fox]

Which keys stopped registering?

- (Numpad)
Right alt
Space
B
N
/
Left arrow
Down arrow
Right arrow

They all stopped registering seemingly at the same time. I'll need to take the cover off to see if the broken rivets actually correspond.

Can a trace break spontaneously under normal use?

[E TwentyNine]

You don't have a rivet problem, you have a trace problem.   You don't need a bolt mod.  Yes, one can "spontaneously" go bad.

Yours is the far right trace on the smallest ribbon connector.   You may want to simply open up the keyboard and reseat the connectors.

If that doesn't work there is likely a break in the trace (sometimes happen where the membrane emerges from under the barrel plate), which can be fixed with conductive tape/glue depending on where it is.

[Fox]

Thanks for the info. Unfortunately, reseating the ribbon didn't restore the function of those keys.

Should I use continuity tester probes to locate the break? I would need to get a multimeter. Is it possible the break is between the layers? If so, would I then have to chisel the rivets off to separate them?

[tp4tissue]

all bolt modding is.. is you chisel out the plastic tabs.. and put a (bolt)(screw)  in its place..

There's nothing electronic about this process..


If you've ever put a nail in the wall.. This is the same thing..   

[tp4tissue]

A good mentality to have is..  if you break it.. Who cares.. JUST BUY ANOTHER ONE..   

[alienman82]

removed.

[E TwentyNine]

Thanks for the info. Unfortunately, reseating the ribbon didn't restore the function of those keys.

Should I use continuity tester probes to locate the break? I would need to get a multimeter. Is it possible the break is between the layers? If so, would I then have to chisel the rivets off to separate them?

The minus on the numpad is the first pad on that trace and since it (and everything past it) is dead the break is above it. 

There's two places I've seen break outside of the sandwich.  When the membrane first comes out from under the barrel plate, and where the membrane turns into the ribbon connector.  Where the rigid greenish part is in this pic:



It would be a miniscule crack that you wouldn't even notice.

If you don't have a multimeter, I'd just get a short piece of thin wire, put it in the last position in the connector, put the ribbon cables in, and while holding down one of the keys shove the wire under the top layer to connect to the trace.  I've actually done this and used the keyboard for months like that (that one is in a box at the moment).

It is possible the break is in the sandwich, but as it's so high up I'm guessing it's in the region of the connector.