Fixing an old RT-101? (NMB space-invader keyswitches)

[Kensey]

I just pulle ou the old RT-101 I hv. You can s som of the letters are no as responsive a thy should e.

(continuing on a working keyboard)

I pressed each of the non-whitespace keys 5 times and this is what I got (any key not mentioned responded 5/5; all the keypad keys responded 5/5 so numbers are those on the top row):

1: 4/5
6: 3/5

e: 4/5
t: 0/5

a: 3/5
s: 1/5
f: 0/5
h: 1/5
k: 2/5

c: 4/5
v: 3/5
m: 0/5

I remember now what happened years ago: I spilled coffee on this keyboard. Some of the letters seem to have benefit from exercise -- t, f and m actually respond well now though not all the time; is there hope it can be restored to fully-working order by cleaning it? If so, how is the best way to do that?

For positive ID, it looks like it's part number 0600002 or 910007 manufactured by NCD, and it has "space-invader" NMB keyswitches mounted through a metal plate, contacting a circuit board underneath. It has narrow green sans-serif capital letters on beige keys, an Option key where right-Ctrl usually is, Caps Lock and Ctrl placed Unix-style and instead of Print Scrn, Scroll Lock, and Break, it has Setup, Line Feed and Break.

[didjamatic]

I have one in my dirty keyboard storehouse but haven't tested it.  It's branded as "Arche" but it's an RT-101

[microsoft windows]

I have a keyboard labeled RT101 but it uses different keyswitches (Sliders on top of domes) and has keys with a rubber matte finish.

[keyb_gr]

Regular isopropyl alcohol should also do. A syringe could be helpful.

Keycap removal is somewhat tricky for these NMB switches, IIRC. Better look that up first to avoid risking damage to the switches.

[Kensey]

Keycap removal is somewhat tricky for these NMB switches, IIRC. Better look that up first to avoid risking damage to the switches.

The cap itself comes up easily, then I see the white top of the switch.  I assume that part comes off; anybody know how?  The whole assembly (what I can see of it) looks just like this:



The page that image is on says the contacts are "usually self-cleaning".  Besides spraying contact-cleaner/alcohol on it, maybe all I need is to work the switch several times?

[sandy55]

The cap itself comes up easily,

Still, you should be very very careful when you pull off key caps from NMB board with space invaders.

After you pull off caps safely, you have to unlock latches which keep a stem within lower part of a invader.
See  this pic.

Added few pictures in my RT8756C page  ( disregard Japanese comments.  )
Color and forms of stems may be different from invaders of your RT-101, but they are basically same..

[Kensey]

That's perfect!  What I'll probably do is try first on a key I don't care about too much if it quits working altogether (also so I can see what a clean one looks like).