Model M rescue.

[Toasty_Ohs]

So small children decided to team up and destroy my Model M that I have been clicky clacking away on for the last ten years.  A bowl of milk finally did it in.

I cleaned it up as best as I could, and waited for it to dry.  However, when I went to plug it in, some of the keys no longer register.  I used a razor knife to take of the plastic rivet ends and really open it up.  This is what I found:

Dark contacts are the bad ones



Some of the paths as bad as well by the look of it.



Here is a closeup.



Has anyone had any good luck with repairing contacts like these, either by replacing them or cleaning them?

Also, I would be willing to purchase replacements if they can be had reasonably.

model 1391401 1'st gen

[0100010]

Order a replacement menbrane from Unicomp - I think they are $10 or so.

[fohat.digs]

I think the Unicomp will completely rehab an M for $30, but you may want your older parts such as the heavy plate.

[Toasty_Ohs]

Order a replacement menbrane from Unicomp - I think they are $10 or so.

Thanks.  I opened up a ticket with them, I will let you guys know how that works out.

[BucklingSpring]

I'm looking forward to read your feedback on this rehab.

Order a replacement menbrane from Unicomp - I think they are $10 or so.

Thanks.  I opened up a ticket with them, I will let you guys know how that works out.

[Toasty_Ohs]

New membrane from Unicomp came in today.  Things are looking good.

There are only two sticking points.

1.  I am going to have to cut the membrane as where the ribbon enters the board does not match up to the membrane.  The other 5 contacts go to a different but close place on the board.  The other end runs out to the indicator lights, so even if I lose them, it is not the end of the world.  I also kept the old ribbon cable from the original membrane.

2.  I need to dremel some holes in the plastic part of the keyboard base to put some tiny bolts through to reattach all the layers.  I went out today to my local hardware store and bought all eight of them that they had.  I am following this guide I found:  http://wiki.geekhack.org/index.php?title=Modifications:IBM_Model_M:Nut_and_Bolt_Mod

Updates to follow.

[E TwentyNine]

1.  I am going to have to cut the membrane as where the ribbon enters the board does not match up to the membrane.  The other 5 contacts go to a different but close place on the board.  The other end runs out to the indicator lights, so even if I lose them, it is not the end of the world.  I also kept the old ribbon cable from the original membrane.

The membrane should be an exact match.  Can you post pictures?

[fohat.digs]

In Unicomp parlance, the black rubber (now white latex) mat between the mylar sheets (some printed and perforated, some only perforated) and the metal back plate is the "blanket"

The plastic piece commonly known as the "barrel plate" is/are "the chimneys" to Unicomp.

The flat connectors are integral to the circuit-printed mylar sheets, and these would be "the membranes" in my opinion, but that's just me.

If someone (cough rootwyrm cough) knows the proper IBM terminology for these parts, it might be helpful in these discussions.

[smknjoe]

So small children decided to team up and destroy my Model M that I have been clicky clacking away on for the last ten years.  A bowl of milk finally did it in.

Are the children up for adoption yet? Priorities have to be maintained.

[Toasty_Ohs]

In Unicomp parlance, the black rubber (now white latex) mat between the mylar sheets (some printed and perforated, some only perforated) and the metal back plate is the "blanket"

The plastic piece commonly known as the "barrel plate" is/are "the chimneys" to Unicomp.

The flat connectors are integral to the circuit-printed mylar sheets, and these would be "the membranes" in my opinion, but that's just me.

If someone (cough rootwyrm cough) knows the proper IBM terminology for these parts, it might be helpful in these discussions.

Good to know!  Thanks.

[Toasty_Ohs]

1.  I am going to have to cut the membrane as where the ribbon enters the board does not match up to the membrane.  The other 5 contacts go to a different but close place on the board.  The other end runs out to the indicator lights, so even if I lose them, it is not the end of the world.  I also kept the old ribbon cable from the original membrane.

The membrane should be an exact match.  Can you post pictures?

Sure.

The new keyboard membrane:



The old keyboard membrane:



The board they attach to:



Detail on the white sticker:



There are some numbers on the membrane.

The old membrane has:

1390345-788 - top sheet
1390352-788 - bottom sheet

The new membrane has:

1379874-809 - top sheet
1404820-608 - bottom sheet

If you look at the top of the thread, the first pic is the bottom sheet and the second pic is the top sheet.

Thanks.

[E TwentyNine]

Your new membrane is meant for a later controller where the top leads and the LED leads went to one connector.

Are you certain you gave them the correct part number when ordering?

Cutting it as you suggest should be fine, but I'm wondering if Unicomp shipped the wrong part or no longer stocks the older style.

[Toasty_Ohs]

Your new membrane is meant for a later controller where the top leads and the LED leads went to one connector.

Are you certain you gave them the correct part number when ordering?

Cutting it as you suggest should be fine, but I'm wondering if Unicomp shipped the wrong part or no longer stocks the older style.

Just heard back from Unicomp, they are saying to cut away the part of the ribbon that does not fit.  Well, we will see how that goes.

[fohat.digs]

Where the heck is Sandy's Bolt Mod?

That was the definitive guide to the procedure. All I can find now do not even remotely touch it.

McMaster-Carr is very cheap and fast with cheap shipping. A pack of 100 will do 2 keyboards.

You don't really need the sheet metal tappers at the bottom, since they are much more expensive, but they are easier at the front.

[E TwentyNine]

Where the heck is Sandy's Bolt Mod?

http://sandy55.fc2web.com/keyboard/repair_model_m.html

[fohat.digs]

That must be a very crude abbreviated early version.

The one that used to be here in the wiki was beautiful - much longer and with far better detail, especially concerning drilling and fitting.

[rowdy]

Bookmarked!

That's a remarkable difference there between the old and the new.  My two were actually in quite good condition (at least the one I have opened was).

[h2gofast]

I can appreciate the sentimental value of the same keyboard, but it might be easier to clean one of the dirty one's from fleabay, or use Soarer's converter for one of the IBM terminal keyboards. 

[wcass]

That must be a very crude abbreviated early version.

The one that used to be here in the wiki was beautiful - much longer and with far better detail, especially concerning drilling and fitting.

i think you are remembering Ripster's post "Sandy's Bolt Mod - American Style".
Ripster did take nice pictures.

[fohat.digs]

I think you are remembering Ripster's post "Sandy's Bolt Mod - American Style".
Ripster did take nice pictures.

That sounds right. Do you know where to find it now?

I have done several, and I don't need a guide any more, but anybody new could gain invaluable insights from it.

[rowdy]

I think you are remembering Ripster's post "Sandy's Bolt Mod - American Style".
Ripster did take nice pictures.

That sounds right. Do you know where to find it now?

I have done several, and I don't need a guide any more, but anybody new could gain invaluable insights from it.

http://imgur.com/a/QroSL

?

[fohat.digs]

http://imgur.com/a/QroSL

This is probably the current version of the guide.

In the one that I learned by, there was some considerable interest and detail lavished on the preparation and finish of the rivet shafts. I have found the I get the best results by leaving the shaft as long as possible, and shaving the top of the "mushrooming" with a single stroke of a sharp chisel blade perpendicular to the shaft. It very clean and easy this way, and the crescent-shaped alignment tabs are safe.

The rude cylindrical grinder shown in this guide looks scary and would be very difficult to control. I did better with a fingernail file, back when I was grinding.

[Toasty_Ohs]

I think you are remembering Ripster's post "Sandy's Bolt Mod - American Style".
Ripster did take nice pictures.

That sounds right. Do you know where to find it now?

I have done several, and I don't need a guide any more, but anybody new could gain invaluable insights from it.

http://imgur.com/a/QroSL

?

Thanks much.  That one looks much nicer.  I went and ordered a set of 100 nut/bolt/washers from that McMaster-Carr company. 

They don't tell you what shipping is going to cost up front, but when I called them, they said it would be around 6 USD.  Have they never heard of flat rate boxes?

So  today I am going to drill out the rest of the old melted rivets and prep the barrel plate.  The guide made it clear that the cut rivets would cause problems.

[dorkvader]

some people like to put washers on, as shown below:
http://wiki.geekhack.org/index.php?title=Modifications:IBM_Model_M:Nut_and_Bolt_Mod

I've done both and prefer washerless.

[fohat.digs]

They don't tell you what shipping is going to cost up front, but when I called them, they said it would be around 6 USD.  Have they never heard of flat rate boxes?

So  today I am going to drill out the rest of the old melted rivets and prep the barrel plate.  The guide made it clear that the cut rivets would cause problems.

You may be astonished at how tiny the nuts and bolts are. The ones that I ordered came in a bubble envelope. And I think that flat rate anything is a minimum of $6 these days.

PS - I always use washers.

[Toasty_Ohs]

Nut and bolt job went just fine.

Most of them don't ever show with the base of the key caps in.

I would guess I used about 50 or so getting the job done.



Please forgive the crappy paint job.  I did it on a whim.  Now I want to sand the thing down and do a better job in a different color.

[ch_123]

Probably too late now, but you can always fix the membrane yourself with some conductive silver gel, a multimeter, and a reasonable amount of patience.

[Toasty_Ohs]

Probably too late now, but you can always fix the membrane yourself with some conductive silver gel, a multimeter, and a reasonable amount of patience.

That sounds a little tricky.  Are there any good tutorials out there on doing something like that?

[ch_123]

I always meant to make one, and I think I have the pictures around required to do so, but here's a few pointers:

I used one of these http://www.ebay.com/itm/1x-Conductive-Silver-Writer-Conductive-Silver-ink-Pen-998-/171057707393?pt=LH_DefaultDomain_0&hash=item27d3d57981. I tried some wire glue but it didn't work.

Basic idea here is that the electrical traces along the membrane can wear out, either due to age or contamination. If you put a layer of silver gel over the trace where it has worn out, it will work once more. You use the multimeter to help figure out where exactly the trace has died (it is unusual for the entirety of the trace to die completely) by testing for continuity.

First of all, make a list of all the keys that are dead. Take apart the keyboard and find the contacts for the dead keys on the top and bottom membrane sheets. Look at the electrical traces on the membrane and take note if multiple keys are located along the same trace, also note that the electrical traces start at the membrane's ribbon connector.

Take out your multimeter and check the conductivity between the start of the trace and the contact of the dead key. If there is indeed a problem with the trace, you'll probably get a reading of zero at this point. (In order to rule out other potential issues here, it's probably a good idea to first test a trace that you know to be good, and also to test the controller by figuring out which combination of row and column correspond to one of the dead keys, and then shorting out the corresponding pins on the membrane ribbon cable connector with a bit of wire) Once you find the dead trace, take the two probes of your multimeter and begin measuring along it to find where the trace has worn out.

I've tried this with two IBM keyboards, one was an SSK, and one was an M4-1. I seem to recall that in both cases, the membrane inside the keyboard assembly was ok, but it was actually the contacts exposed on the end of the ribbon cable that had become non conductive (the ones in question were both black). Depending on how fried they have become, it could be possible to fix them by applying a layer of the conductive gel onto the affected contacts (making sure that you don't create a short between two neighboring contacts). If you're out of luck, you end up having to create your own trace along the top of the ribbon cable, because the traces on the ribbon cable are sealed from the outside world.