Yet another IBM 5251 restoration

[pansku]

I finally managed to grab myself by the neck and actually start doing something and lo and behold the 5251 from Nuum is now in pieces
Before:

Before

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After:

Upper case and case bottom

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Dozen of beam spring switches

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Switch plate

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PCB

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PCB backplate

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Edge connector

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Now I've got a plan but I'm not sure about some of the things as I haven't done anything on this level earlier

• Get the xWhatsit working without putting pressure on the connector. I think a good cleaning could help in this. After cleaning one of the pads with pure isopropyl my multimeter beeped for continuity on a much larger area on the pad. Maybe the pads are just dirty.
• Bring back the solenoid. The solenoid driver just came in mail so I just need to solder one connector and put it together in final assembly
• Get rid of the yellow in the keycaps. I'm not sure how retrobrightin works as the caps are white legends on black or gray. Also I'm not quite sure where to find a good ready made mixture in Finland. I haven't exactly met any of the chemistry students at uni..
• Have the switch plate and PCB backplate yellow passivated. Not sure about the correct term but I'm looking for original looking result such as this:
  
• Clean the top case. What solution have you used to clean dirty plastics before?
• Remove rust from the stems and coil springs. I can get a good selection of cleaning agents from Wurth stores. Any recommendations on something that will easy the stem removal without harming the plastic? I think Rost Off should remove the rust once the parts are separated. I've also got some Teflon spray 10µm laying around and that should be good for lubing the switches, shouldn't it?
• Did I miss anything obvious? Any, literally any tips would be appreciated

Disclaimer: No switches have been harmed, so far but boy is reattaching the fly plates a huge pain in the ass

[codemonkeymike]

To get the plate to that state I think it was either heat treated (annealed) or chemically oxidized or possibly anodized. I am not exactly a materials chemist but I play one on the internet. IMO you should clean it thoroughly then seal the surface rather then trying to remake the surface. I have used everbrite on the door knobs in my house and have held up well. https://www.everbritecoatings.com/how_t ... icture.htm

As for removing rust from the springs I used Naval Jelly. Works well but reeks of sulfur.

[pansku]

To get the plate to that state I think it was either heat treated (annealed) or chemically oxidized or possibly anodized. I am not exactly a materials chemist but I play one on the internet. IMO you should clean it thoroughly then seal the surface rather then trying to remake the surface. I have used everbrite on the door knobs in my house and have held up well. https://www.everbritecoatings.com/how_t ... icture.htm

As for removing rust from the springs I used Naval Jelly. Works well but reeks of sulfur.

I read that the yellow passivation is some form of electrolytic zinc coating with some chrome thing mixed up in it. One of the sites has this picture:

and the result seems to be what I'm looking for, a yellowish corrosion resistant coating which shines in the colours of the rainbow. Stupid me just can't figure out the word in english for the process.

[Slom]

https://en.wikipedia.org/wiki/Galvanization

followed by

https://en.wikipedia.org/wiki/Chromate_ ... on_coating

[pansku]

Thank you! I do feel dumb now because of my poor google-fu

[seebart]

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Nice work so far BTW pansku!

[codemonkeymike]

https://en.wikipedia.org/wiki/Galvanization

followed by

https://en.wikipedia.org/wiki/Chromate_ ... on_coating

Now I feel stupid, we did this in Chem II lab.

Anyway, Galvanization is easy Chromate conversion is hard. Also Chromate ions are toxic. We had to use nitrile gloves, face-masks and had toxic waste removal for Chromate. I bet you can find an electroplating company to do it for you but I cant imagine it being cheap.

[pansku]

Do any of you happen to know the original painting method of the bottom part? When asking people I know I got mixed responses. One said powder coated and other one said you can't achieve such a grainy surface by powder coating. Now I'm just left confused and not knowing which companies to quote from for a fresh coat of paint.

Also has ellipse ever mentioned which RAL or Pantone color he ended up using? It looks prerry similar to the one on the beam spring

[pansku]

Yikes, it took me a few weeks to find a place who will do galvanization and chromatic conversion to private customers without a bank busting price(30€). Just dropped of the 2 pieces for the plating and hopefully by next week I'll see what the results looked like. The plate which holds the switches is quite corroded and the surface isn't smooth even after sanding with powertools. Good thing the pieces are super thick.

But most important thing I need to do before going back to hometown for x-mas is finding the chemicals to hopefully de-yellow the keycaps. No one at either the university electronics club nor radio club had done such work so no tips from there. Have any of you guys tried retrobrighting white on gray or white on black keycaps? I could really use some tips on that process

[pansku]

Bumperino.

I'm still curious if anyone has succesfully retrobrighted/de-yellowed mostly dark keycaps. I've only found the thread of XMITs cautionary tale.

Some of the caps really could use some treatment:





The background is white paper towel to give you an idea about what white should be in the picture

[Sangdrax]

I've done dark keycaps but they required repolishing to get it right. Not sure how you'd do it without ruining the texture on caps like those. Maybe just submerge in liquid peroxide indoors and watch it closely. You want the retrobright to work slow enough you catch it before the colors start to leech.

[andrewjoy]

Look at the video the 8 bit guy did . He heated the plastic in a pan with the liquid type not the cream and it was super even.

[orihalcon]

Selectric caps will work, but the texture will be smooth. Perhaps they can be sandblasted to add texture?

[pansku]

Thanks for the tips. I watched that 8bit guys videos and I'll try source some hydrogen peroxide and test on 1 "easily" replaceable alphanumeric first. Thanks to some folks at brussels over 12% concentration requires a purchase license for private customers but not companies???. I'll ask a pharmacy for pricing this week to see if I can get some from close to home because the mail company is mega slow near christmas.

The plates came back from being galvamized, but due to communication error they are only zinc plated. I don't have the energy to get them chromatically converted so the final finish will have to wait for a later date. The plating did only end up costing 10e so it's not the end of the world. I'll grab some pictures when I head back home for christmas. Luckily my dad had some PTFE-spray lube for the switches so I can save some money. Now I just need to find a plastic safe penetrating lubricant from the garage. Small steps of progress

[pansku]

Some controller related pics:
The original cable is over 11mm thick And despite the german keycaps the cable says Italy and Data/Ditta on the other side

Original cable

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But the connector is in shocking condition

Original connector

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And the ICs date the controller back 40 years to 1977

Some ICs with dates on them

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Metal bits:

Bottom side of the PCB backplate

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Top side of the PCB backplate

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Top side of the mounting plate

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Removing the paint revealed that this part also has a dedicated part number. Too bad that the underside is heavily corroded. Even sanding with power tools wasn't enough. Good thing it will hide from sight.

Underside of the mounting plate

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And a family shot of some heavy steel:

All the big metal parts

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[pansku]

The monologue continues. Switches are now torn apart and everything is cleaned except stems and coil springs which need some derusting. The switches were a giant pain in the ass to disassemble, but once I got a can of Würth Rost Off Plus things got easier. The really bad thing is that I won't get the hydrogen peroxide until 2.1.2018 due to some failure in the ordering system of the online store So keycaps will have to wait for their turn. Unfortunately also parts of the sliders and housings have discoloured to a more rusty tone. On the positive side I haven't broken anything, yet, and the Rost Off didn't damage the plastics nor the O-rings. Some pics of the current state:

Housings and sliders

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Foam parts removed

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O-rings cleaned

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Now a question to those who own a beamer, do your keyboards have plastic or anything between the two metal parts which hold together the PCB and switch assembly? Mine had some electricians tape and the Displaywriter guide had plastic parts. I'm not sure if I should put some tape there when it's time to assemble the beast.

[codemonkeymike]

[...]

Now a question to those who own a beamer, do your keyboards have plastic or anything between the two metal parts which hold together the PCB and switch assembly? Mine had some electricians tape and the Displaywriter guide had plastic parts. I'm not sure if I should put some tape there when it's time to assemble the beast.

So between the two plates were they bolt together should be a thin piece of foam. One side of the foam is adhered to the switch plate and the other side of the foam is adhered to a thin piece of plastic. I think the foam is 1/16th inch but I am not 100% on that.

[pansku]

Thanks for the picture. I think I'll assemble it roughly the same way it was then.

[Nuum]

Not sure about the foam between the thin plastic sheet and the switch plate, but the plastic sheet itself was where I put the electric tape. Not sure, why I did that, though, probably because I didn't find a good method to attach the plastic strips again.

[pansku]

Oh shit. I didn't notice the strip back in november. Anyways more progress:

Mmm beam springs

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Packed up and ready to rumble

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[pansku]

Time to cook some keycaps this weekend. Who woulda thunk that the cheapest source of hydrogen peroxide I managed to find would be a plant nutrient

Great things come in surprising packages

IMG_20180104_142825.jpg (2.75 MiB) Viewed 5434 times

[Wodan]

Damn even the good 12% stuff ...

[codemonkeymike]

@pansku, what did you end up doing to the raw metal plate? Did you clear coat it or something?

[pansku]

At the moment it is galvanized with zinc. I will consider getting it chromate converted if I happen to come across another company that is willing to do it for cheap.

When the business only has 2 guys and the other one didn't even have a clue what needed to be done despite the first one agreeing on what needs to be done and for how much. And when I picked it up the first guy still didn't know I had brought it there when I even talked to him on the phone the morning I gave it to his brother/associate. That kind of experience really makes you lose trust on the company and the people behind it.

[codemonkeymike]

At the moment it is galvanized with zinc. I will consider getting it chromate converted if I happen to come across another company that is willing to do it for cheap.

When the business only has 2 guys and the other one didn't even have a clue what needed to be done despite the first one agreeing on what needs to be done and for how much. And when I picked it up the first guy still didn't know I had brought it there when I even talked to him on the phone the morning I gave it to his brother/associate. That kind of experience really makes you lose trust on the company and the people behind it.

Indeed, I was looking for someone to do a chromate coating on myne. Zinc is easy but a little moisture will set some oxidation in motion on it.

[pansku]

Babysteps:

Bottom plate left to get a fresh coat of paint. Derusting in progress and retrobrighting test going on

Rust begone!

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Before

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Test keycap brewing

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[pansku]

Sigh, the retrobrighting sure didn't go as planned. Test methodology: 1 litre of watee, 2 capfulls of H2O2 at start, 1 capfull at around 1h, 1 capfull at around 2h. Grey one sunk at 00:00:00 as water hit 70°C, black one at 02:00:00. Water tempereture 70°C ± 5°C whole time. Results not so good.

Fail 1

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Fail 2

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Epic fail 3

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I'm going to have to come up with another plan or these caps shall remain yellowed. UV won't be an option for months as the sun shines so low and so little time per day at 60°59' N

[codemonkeymike]

Did you stir it the whole time or did you let the cap sit at the bottom of the pan?

[pansku]

It basically stirred itself as when the tempereture and concentration changed the keycap moved between stages of sinking, floating somewhere in the middle and floating on the surface.

[pansku]

Well well well, what do we have here?

The bottom part now has a fresh coat of paint I couldn't resist putting it all together. Also now it has a solenoid driver too I just hope the sound gets better when it is fully assembled with feet.

I still need to clean up the case top and try retrobrighting again in the summer when UV radiation is available and get some feet as only 3 of the original 4 are to be found. Unfortunately one of the stabmounts on the spacebar has broken somewhere in transport so now it has a temporary fix. Pics:

The body

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Fresh coat of paint

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A solenoid

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A quick typing demo: