To save an Unsaver

quantalume · 19 Oct 2014, 18:47

I recently acquired an IBM Model F 5085 terminal keyboard from elecplus, and it is unfortunately in less-than-ideal condition.

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Hmmm...I wonder what is "BAD" about this board? I thought I'd use this thread to chronicle its restoration. The first step will be to assess the condition of all component parts (case, keycaps, metal plates, pad card, barrels, pivot plates, controller, feet, etc.) and then develop a plan of attack.

Grond · 19 Oct 2014, 18:54

Probably made in 1987

quantalume · 19 Oct 2014, 19:01

Case

In addition to being filthy and scraped up and inscribed with a permanent marker, the case has also had the screw sockets ripped out of it:

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These rear screws actually support the bulk of the weight of the keyboard when the feet are extended, so it will be important to repair them properly. Fortunately, most of the rest of the plastic is still attached.

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Muirium · 19 Oct 2014, 19:33

Those bad boys get treated rough sometimes. What's your battleplan for the plastic case: a paintjob? A sanding? I'm glad it's not me having to make these decisions, or implement them. But with skill, this will be a great restoration.

quantalume · 19 Oct 2014, 19:45

Grond wrote: ↑Probably made in 1987

1983, actually.

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beltet · 19 Oct 2014, 19:47

Good luck with the restoration!
With one of these in your hands you must get quite much "energy" to complete the task?
Will follow this.

quantalume · 19 Oct 2014, 19:54

Muirium wrote: ↑Those bad boys get treated rough sometimes. What's your battleplan for the plastic case: a paintjob? A sanding? I'm glad it's not me having to make these decisions, or implement them. But with skill, this will be a great restoration.

If the keyboard is dropped (or something dropped on it) with the feet extended, then those screws could easily get ripped out. I consider this one of the weak points of the Model F design. The other thing which can happen is the rear part of the case becomes warped from supporting the weight of the keyboard for years. This is particularly prevalent on the heavy F-122s.

My approach to the case will be to first attempt to clean it up and remove the ink. Depending on how this goes, I will decide whether or not it needs to be painted.

quantalume · 19 Oct 2014, 20:29

Continuing the assessment...

Front barrel plate, ewww. Probably one of the worst I've seen.

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Bottom plate looks good!

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There is a set of dip switches on one side...

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...and on the other side is a...what the hell?

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The DC resistance is about 14 ohms, so a speaker, maybe?

Spoiler:

quantalume · 19 Oct 2014, 21:12

The bottom, plastic piece of the case is in good shape, as are the connectors.

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Pad card backplate looks good, as does the controller.

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I don't think anyone has reverse-engineered this controller yet. Hiding behind the ribbon cable is one of the IBM capsense ASICs.

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The foam is in pretty rough shape and will probably have to be replaced.

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Aside from being dirty or missing, the caps appear to be in fairly good shape, aside from a few which have received minor trauma.

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The bottom row modifiers are often the first to get lost on Ms and Fs.

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cinnamonrollz · 19 Oct 2014, 21:21

For the plastic try loctite repair extreme all temperature. It works complete wonders on model m barrels and cracked laptops. Its says all temp but works best at 70 degrees f or above it also takes 24 hours to set and doesn't stick to electrical tape.

Honestly its one of my favorite adhesives because of how damn strong it is. Best $3 I've ever spent at walmart!The laptop that i repaired with it has taken immense beating and still survives with only a hairline mark where it snapped first.

andrewjoy · 19 Oct 2014, 21:47

get one of them scouring pads you use on dishes with the soap in and give the case a once over with that, it worked wonders on my XT, just dont scrub too hard or you will remove the texture

pyrelink · 19 Oct 2014, 22:15

Looks pretty rough, but with a good bit of work, should turn out just lovely. Good Luck!

That speaker assembly is quite nifty! I love how the sound is physically adjusted with the plastic plunger screw thingy.

xwhatsit · 20 Oct 2014, 12:47

That speaker thing is intriguing, I remember seeing it on photos of Kuato's board but I thought nothing of it and must have though it was part of the mechanical assembly of the case somehow. 18 ohms is a bit low for the solenoids (they are 30–35 ohms I think); the interesting thing is that that would be a very similar current draw if it were powered from 5V instead of 9V like the solenoids are. Have you tried putting some juice on it yet?

andrewjoy · 20 Oct 2014, 13:15

if you want i can fix that unsaver up for you , just send it to me and i will get it looking like new for you

you can have it back in say 50-60 years

quantalume · 20 Oct 2014, 18:05

xwhatsit wrote: ↑That speaker thing is intriguing, I remember seeing it on photos of Kuato's board but I thought nothing of it and must have though it was part of the mechanical assembly of the case somehow. 18 ohms is a bit low for the solenoids (they are 30–35 ohms I think); the interesting thing is that that would be a very similar current draw if it were powered from 5V instead of 9V like the solenoids are. Have you tried putting some juice on it yet?

I tried driving it with my audio generator, which has a 600-ohm output, but I didn't really hear anything. I didn't try anything with a lower output impedance. Chances are, it's probably driven with a TTL square wave, hence the need for a mechanical volume control.

Hmmm...there's that red dot on the side. Maybe it's self-oscillating and I've already put reverse polarity to it.

xwhatsit · 20 Oct 2014, 22:01

You think they'd do something about keying that female header though (or using colour-coded wire) to stop connecting it up wrong though; I didn't see the red dot but if it's on the device itself it'd be pretty hard to trace it back through twisted wires?

quantalume · 21 Oct 2014, 18:28

Great success!

After 20 minutes of scrubbing, alternating between isopropanol and hot, soapy bleach water, the case came clean!

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It's a good thing that this case has the color baked into the plastic (XT, AT, 4704 Model Fs are painted), because I had to do a lot of scrubbing.

Next, I set out to repair the screw sockets. I couldn't find the Loctite glue that cinnamonrollz suggested, so I went with my original plan which was to use cyanoacrylate gel and accelerator. After checking the fit, I applied glue to the pieces, assembled them in place, then quickly shrunk a piece of heat-shrink tubing over the post to hold everything together.

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After applying accelerator to quickly cure the pieces in place, I removed the heat shrink tubing and applied additional glue to fill in any voids.

Next, I wrapped some 26-gauge wire tightly around the post and put a liberal amount of glue on top of the wire to hold it in place.

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I'm fairly confident that the repaired posts are stronger than they were when the keyboard was new.

Now, on to the internals...

Nuum · 21 Oct 2014, 18:51

It's awesome how clean you got it! I like your solution with with the heat shrink and then the wire.

quantalume · 21 Oct 2014, 19:18

A neater solution would have been to use brass tubing like this instead of the wire, but I was anxious to get the job done with materials on hand.

andrewjoy · 21 Oct 2014, 20:33

It looks amazing very clean

pyrelink · 22 Oct 2014, 01:09

Wow, excellent job cleaning. Wish that all the Model F boards had baked on paint... The screw post also looks great. Was the wire and glue simply as extra reinforcement?

quantalume · 22 Oct 2014, 01:27

Yes, and it was probably unnecessary in that regard.

andrewjoy · 22 Oct 2014, 10:16

We demand pictures of the finished unsaver !

quantalume · 22 Oct 2014, 13:17

andrewjoy wrote: ↑We demand pictures of the finished unsaver !

Relax, it's going to be awhile.

Top plate is looking pretty nasty.

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Some of the foam stayed behind with the top plate.

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You can tell that there are six extra positions that are not used: two between Ctrl and Alt and four in the navigation cluster.

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The pad card looks good and has support for the extra positions. The controller interface has the standard Model F 2-8-2-16-2 hole pattern.

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I wonder which variant of this form factor actually used those extra positions? Perhaps IBM put them there just in case. It would be impossible to take advantage of them without cutting the case.

Next task: strip the rust from the top plate and paint it.

andrewjoy · 22 Oct 2014, 13:22

the ones on the nav cluster look ok to use the one on the left between the left control and alt does not look liek it is connected on the PCB but i could be wrong.

that nav cluster is screaming out to be turned into a number pad IMO

Foam does not look that bad ether its passable, pcb is in nice condition. is there solder mask on it as it looks like a bare pcb to me

quantalume · 22 Oct 2014, 13:26

There is solder mask, it's just brown rather than the usual green.

andrewjoy wrote: ↑the ones on the nav cluster look ok to use the one on the left between the left control and alt does not look liek it is connected on the PCB but i could be wrong.

Good eye! I hadn't noticed that.

Parak · 22 Oct 2014, 15:20

quantalume wrote: ↑ I wonder which variant of this form factor actually used those extra positions? Perhaps IBM put them there just in case. It would be impossible to take advantage of them without cutting the case.

In the case of some unsavers, this one included, the 4 around the nav cluster are usable pads. Should be the same with the one between right alt and enter (I did not test it), but the left one is not connected. For the nav cluster ones you'd have to drill the plate, ideally with something like a countersink bit since I did not have good results with regular bits. For the case it's simpler - make rough cuts with dremel, then carefully file and sand away the excess.

My own results on this were acceptable, but not exactly pretty plate wise or precise:

http://imgur.com/a/W3Hci

quantalume · 22 Oct 2014, 15:38

I thought you did a pretty good job on the holes. Anything over about 1/4-inch in thin steel is going to be a pain to get smooth unless you have a very rigid drill press and a firmly-clamped workpiece. They probably used some sort of punch in production. For a few holes, I think I would drill a little undersize and then finish off with a reamer.

I see your board had fish paper under the controller too.

kuato · 22 Oct 2014, 20:08

Great job so far quantalume. This unsaver is going to look great when finished

andrewjoy · 22 Oct 2014, 20:13

indeed looks amazing so far , i need to finish the thread on my 122.

Oh and if you do make a numberpad put a tab key on it , all the cool kids have a tab key on there numberpad