deskthority

Photos for a lovely board I got from XMIT last month. Thank again XMIT!

RAFI Hall effect switches: wiki/RAFI_RS_76_C (white slider variant)

Linear switch. It's not really the smoothest switch in my opinion; the lack of stabilizer on its moderately long keys (Ctrl, Backspace, Tab) really made them hard and scratchy to press. The regular keys and stabilized keys are fine.

Initial state


Stainless steel backplate and coiled cable


Dusty PCB, yum.


PCB with keycaps on


Doubleshot caps


PCB after tap water! The switches are lubed with mineral oil.


Backside showing the linear 4-pin soldering, typical of hall effect switches.


Putting on some new caps (sorry for the lighting)


End product.
I feel terribly sorry that I broke the += key's switch stem when I was trying to adjust the key caps. That RAFI cap was way too tight and broke the stem beneath when I was pulling it

This board works perfectly with a Soarer's converter. Gotta get used to having += right beside the left shift then.

Very nice, looks good with those caps. Interesting that the switches are lubed with mineral oil.

So that black thing on the back is a large stand?

Very cool, thanks for posting! I'm glad the keyboard made it safely. It cleaned up nicely!

It's interesting to see the PCB and all of the other potential switch locations.

The switch scratchiness is a result of dirt. Hopefully the lubrication helped. If not then the plastics themselves are probably scratched. Laboriously polishing the plastics with a polishing wheel or point on a Dremel or other rotary tool could help.

As for the broken slider: Could you perhaps steal one from a less worth key such as Pause/Break or Insert?

seebart: Yes, that's a large stand.

Seebart: Yes it's a stand, though it's definitely not as good as the spherical rubber feet. The feet make a great angle and make the board utterly nonslippery on the table.
What do you use to lube the switches btw, is it silicone lube?

XMIT: Yes I could fix it by soldering Pause/Break or the key beside left shift, I also found some suppliers of the switches online, it's crazy expensive btw, one of them wants 3 USD each but the minimum order is 25. A chinese supplier wants 50 CNY each, maybe I'll see if that works out.

Yes I did try this once and it was a total waste of time, no good too "pasty":

http://www.liqui-moly.de/liquimoly/prod ... nt&land=DE

I need something with a more oil like consistency.

when you wash the pcb, does water not get into the switches? If so how do you dry them?
I feel like a wimp in using cotton bud daped with alcohol...

seebart - The mineral oil I used probably works, it's pretty thin and won't spoil like cooking oil.

need - These switches have an open design (the sliders and springs are entirely out in the open) so water can't be stuck inside. I would definitely rethink if it's a PCB with Cherry MX switches.

OK thanks dzhoou I'll try something like this:

Sorry to read about the broken plunger. I've searched through my bits and pieces and found a solitary switch that I could offer.

Those are beautiful, well-preserved caps that go surprisingly well with the board, despite being from another era.
They seem to be taken from a German Siemens board of the System 6.000 series (late 1970s or early 80s).
Is that correct? Have you got photos of that board, too?
And may we use your photos in the wiki?

OleVoip: Sure, any photos can go into the wiki.
The caps are taken from this keyboard: http://www.ebay.ca/itm/SIEMENS-6AC6975- ... SwKtVWujZ4
I originally bought it in hope for it to have hall effect switches, but it did not.

You have the switch I need? That's great! Please PM me so we could work out the details.

Ah, that board was made for a Siemens 3974 R "Remote Datensichtstation" (like this), the only model in the 3970 family that had RAFI keys; it quickly was superseded by the 3975 with Siemens STB keys. The board is over 30 years old and you got it NIB. Amazing.

Damn the Datensichtstation looks ancient indeed. It's not actually NIB, it only came on a shipping box but the item itself is new aside from a few scratches. Now I feel sorry for taking the board apart ;D