deskthority

Got my 5251 from der rustmaster himself today. Survived the trip overseas without a scratch, and took about 2 weeks total to reach southeast US thru DHL. I assume everyone from EU has long since gotten theirs, curious to see what condition yours arrived in. Here's mine:


(seller image)


Keys and stabs are in great shape. All the switches seem to work fine, two of them have a more "hollow" sounding click on the DRUCK and EING keys, is that just from well-worn fly plates?


Wow, the contamination shield was a mess. Got right to work at removing it, it was doing more harm than good at this point.


Then I saw this.. lots and lots of corrosion. Did some searching, and saw Muirium's board had a very similar look


Tried some fine-grit sandpaper, it takes some of the lighter corrosion off and oxidation, but the darker parts are deeper ingrained


I'm really hoping the capacitive pads aren't corroded too, it looks like there's a layer of rust on the top where it sticks out


Date and partNo, looks like a '78 board


Strangest find was this folded up inside. I'm guessing it was some kind of repair sheet with thermal ink? Maybe some German members can chime in about these guys. I've never heard of them before, and a Google came up with nothing useful..

All in all I'm happy to have a project for what I paid! Wondering if I should bother taking the individual switches/board apart and risk breaking them? I do have a beamspring-Xwhatsit on the way, so hopefully I'll find out soon if it works!

Ouch. That rust! I bought 2, but won't get them for a while. I'll let you know how mine are. At least one of mine has that yellowed P key like the seller image, so at least you got lucky on that!

photekq wrote: Ouch. That rust! I bought 2, but won't get them for a while. I'll let you know how mine are. At least one of mine has that yellowed P key like the seller image, so at least you got lucky on that!

Really hope it's just surface rust from moisture, and that the capsense is still all good. Will wait to see if it works before I crack that mess open.

Invisius wrote:

Spoiler:

I'm really hoping the capacitive pads aren't corroded too, it looks like there's a layer of rust on the top where it sticks out

I am fairly certain that is just a layer of padding, I believe my 3277 has something similar. Unless you're talking about those white spot-looking things, in which case I have no idea. Hope your board is okay in any case!

Invisius wrote:

photekq wrote: Ouch. That rust! I bought 2, but won't get them for a while. I'll let you know how mine are. At least one of mine has that yellowed P key like the seller image, so at least you got lucky on that!

Really hope it's just surface rust from moisture, and that the capsense is still all good. Will wait to see if it works before I crack that mess open.

If the foam is as degraded as the contamination shield and plates, it might not work even if the PCB is fine. I recommend gloves when you replace the foam—that sticky glop is the stuff of nightmares.

Ratfink wrote:
I recommend gloves when you replace the foam—that sticky glop is the stuff of nightmares.

Just dunk it in the sink for a good soak and then scrub it with hot soapy water. That will take care of all but a few stubborn spots that will come up with a fingernail.

Ratfink wrote:
I recommend gloves when you replace the foam—that sticky glop is the stuff of nightmares.

Hopefully it's still intact, will post an update in a few days once the Xwhatsit comes in

fohat wrote:
Just dunk it in the sink for a good soak and then scrub it with hot soapy water. That will take care of all but a few stubborn spots that will come up with a fingernail.

Thanks, I also read about the vinegar bath working well for the real stubborn stuff. Is the top plate easy to remove without damaging the switches? I can't seem to find anyone's method to this.

I found a document in PDF format for this terminal and keyboard. From the PN on the inner assembly, that was a German typewriter-style assembly. In country configurations, they could be data entry, typewriter, or data entry with proof reading characters. http://bitsavers.informatik.uni-stuttga ... _Jun79.pdf

Invisius wrote:

fohat wrote:
Just dunk it in the sink for a good soak and then scrub it with hot soapy water. That will take care of all but a few stubborn spots that will come up with a fingernail.

Thanks, I also read about the vinegar bath working well for the real stubborn stuff. Is the top plate easy to remove without damaging the switches? I can't seem to find anyone's method to this.

If it's like my 3277, it's all just screws. After you have it disassemble it to the point where you just have the top plate and the switches, you can just remove each individual switch module. Each are held in simply by the two clips at the top of the switch.

elecplus wrote: I found a document in PDF format for this terminal and keyboard. From the PN on the inner assembly, that was a German typewriter-style assembly. In country configurations, they could be data entry, typewriter, or data entry with proof reading characters. http://bitsavers.informatik.uni-stuttga ... _Jun79.pdf

How cool would it be if we could just order all these parts? I'd be putting custom versions of these together from scratch all day

emdude wrote: If it's like my 3277, it's all just screws. After you have it disassemble it to the point where you just have the top plate and the switches, you can just remove each individual switch module. Each are held in simply by the two clips at the top of the switch.

Well since it's so easy, I just decided to take it all apart and see where I'm at. A pair of needlenose pliers and an hour later:


Bottom piece isn't in such bad shape, going to be easy to just dunk this one




Here's my new problem. The foam is in pretty good shape, but I can see corrosion under it in some parts. It's glued to the metal, and pulling it just causes it to break apart. I definitely don't have any replacement foam, so what should I do now?


On the plus side, the capacitive board is in great shape. Just needs some light cleaning and it'll be ready for primetime.

I think craft foam will work satisfactorily as a replacement, maybe this GH thread can help?

emdude wrote: I think craft foam will work satisfactorily as a replacement, maybe this GH thread can help?

Hmm thanks for that. From what I've read on here, 2mm foam is too thick for beam springs, and 1-1.5mm is ideal. So that means the 1/16th Michaels foam should work just about perfect for our application.

It'll probably take hours to cut all the holes, though. Doing just a border like the people in that thread isn't an option here..
Almost makes me want to find a way to surface remove it by hand.

Hopefully, you can find some easy way to take care of that. Silly idea, but it might be worth looking for some kind of special hole puncher that can punch holes that are roughly the size of the ones on the original mat.

I can say from experience that craft foam doesn't work well for beam spring boards. I tried that first for my Displaywriter board; it's too hard and makes it difficult to install the switches in the top plate, and if I remember right, it made tensioning the screws very difficult. I ended up using some roughly ½"-thick, soft foam rubber, which compresses to almost no thickness easily and solved every problem I was having with the thing.

A leather punch makes quick work of all those holes. I made my own on a lathe, but it was soft steel and got really dull by the end of cutting the foam that finally worked. I made a cutting template by measuring the top plate and making a vector drawing of where all the holes go, then printing that and gluing it to the foam. It was time-consuming, but worth it considering that I had to make several attempts to get a foam that worked well. The actual cutting doesn't take more than an hour unless you end up having to do it twice like I did.

Ratfink wrote: I can say from experience that craft foam doesn't work well for beam spring boards. I tried that first for my Displaywriter board; it's too hard and makes it difficult to install the switches in the top plate, and if I remember right, it made tensioning the screws very difficult. I ended up using some roughly ½"-thick, soft foam rubber, which compresses to almost no thickness easily and solved every problem I was having with the thing.

A leather punch makes quick work of all those holes. I made my own on a lathe, but it was soft steel and got really dull by the end of cutting the foam that finally worked. I made a cutting template by measuring the top plate and making a vector drawing of where all the holes go, then printing that and gluing it to the foam. It was time-consuming, but worth it considering that I had to make several attempts to get a foam that worked well. The actual cutting doesn't take more than an hour unless you end up having to do it twice like I did.

What thickness did you try for the craft foam, and if you don't mind, where did you find that nicer stuff? I don't have any kind of punch or lathe, so it's starting to look like removing this corrosion by hand is the way to go.

Nice catch! Looking forward to your restoration pics!You could try o-rings, check my 3101 restoration (I'm on mobile, so I can't link right now), #15 soft ones should work.

chzel wrote: Nice catch! Looking forward to your restoration pics!You could try o-rings, check my 3101 restoration (I'm on mobile, so I can't link right now), #15 soft ones should work.

Wow, that's a real clever idea. I completely missed your resto when searching for advice, some great pictures in there. Do the switches wobble at all after a few months of regular use?

Hope to use this at least part-time in rotation for my desktop! The case paint needs some TLC, I haven't decided if bare metal would look good on a massive hulk board like this.

Thank you! The middle row twists (no wobble though) from the beginning because the orings I used are stiff (either 70 or 90A, I can't remember now) and the ones on the edges don't compress enough to let the middle ones engage. It works nicely, but I plan to test some foam at some point.

chzel wrote: Thank you! The middle row twists (no wobble though) from the beginning because the orings I used are stiff (either 70 or 90A, I can't remember now) and the ones on the edges don't compress enough to let the middle ones engage. It works nicely, but I plan to test some foam at some point.

Do you mean the switches in the center row don't work at all? Makes sense that they rotate a bit, but I suppose I could try softer rings. A local hardware store has them with 1" OD, 3/4" ID and 1/8" wall, does that sound right for the thickness?

No, the switches work perfectly! They just twist a bit. I don't recall the measurements but search for paintball tank o-ring (I don't think they are 1/8th thick, more like 1/6th)

chzel wrote: No, the switches work perfectly! They just twist a bit. I don't recall the measurements but search for paintball tank o-ring (I don't think they are 1/8th thick, more like 1/6th)

Found some Nitrile rubber ones here https://www.amazon.com/dp/B000FMWM1I for a decent price
They also have silicone, neoprene, poly and "viton" versions in 1/16th. I'm assuming that was a typo, since the paintball tank spec says 1/16

I'd suggest softer ones, around 50A, but if you want to get a feel for the "mod", the ones you linked are fine.
Buna-N works, urethane is to stiff, soft silicone would be best I guess.

Invisius wrote:

Ratfink wrote: (snip)

What thickness did you try for the craft foam, and if you don't mind, where did you find that nicer stuff? I don't have any kind of punch or lathe, so it's starting to look like removing this corrosion by hand is the way to go.

A cheapo leather punch set can be bought on Amazon for about $15, and will make much nicer holes than you could cut with a knife. If, that is, you decide to go with foam; I see lots of o-ring talk appeared overnight.

I don't remember what thickness the craft foam was, sorry. It was over a year ago, and I don't have any of it left (most is in the landfill). You won't find this next bit helpful either: I found the foam I did use in a box of scrap foam.

Finally, some progress!


And wow, what a difference the vinegar made! I need to find a topical way to do the side legs, since I don't want the foam to break down.


In the meantime, the case needs some paint work. Here's what it looks like slapped together- there's a 3-inch wide spot below the keys where the top coat wore down. Is there any way to sand, prime and touch up the area, or am I stuck doing a full repaint?


Also threw the Xwhatsit beamspring I had on, and all the switches work! Set the voltage threshold at 126, and I don't get any double presses or skips.

I am having problems with the solenoid driver, though. At first I thought my solenoid was bad, but I threw a multimeter on the two headers and it's only putting out 5V or so. Aren't these supposed to be 40-50V? I did set up the addon header to solenoid/buzzer in Xwhatsit software.

Siiiiiick .

Invisius wrote:
Is there any way to sand, prime and touch up the area, or am I stuck doing a full repaint?

Don't even consider anything but a complete paint job.

It is heartbreaking to lose the original natural finish but whatever there is in the end, it must be consistent.

Chyros wrote: Siiiiiick .

Thanks man!

fohat wrote:

Invisius wrote:
Is there any way to sand, prime and touch up the area, or am I stuck doing a full repaint?

Don't even consider anything but a complete paint job.

It is heartbreaking to lose the original natural finish but whatever there is in the end, it must be consistent.

Might as well at this point. Thinking about trying something temporary like plasti-dip in the meantime, just to see if I like a color. I've seen some black painted beamsprings, but never a behemoth like this! Have you ever tried paint stripper vs good old sanding?


I also drew up a custom card insert based on my displaywriter original. Here's a temp copy from my cheap printer, gonna get some nice manila stock and borrow my buddies' hi-res printer for the real deal. Would be glad to share the PSD if people are interested.

share, always share

A little while back I restored an IBM Bigfoot that got quite some corrosion going on. Used sandblasting to remove the rust. Unfortunately, the pics I took weren't that great:
http://imgur.com/a/tUbRz
There is one really nice pic though showing the progress halfway through:


All that's silver/shiny used to be rusty.

Bottom side was completely rusted:

That looks fantastic Invisius! You did all the work right there I have ahead of me! That's what I want my 5251 to look like also! Really nice job.