NMB HiTek Space Invaders Black Keyboard

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XMIT
[ XMIT ]

23 Feb 2015, 04:11

[Full resolution photos are at https://plus.google.com/photos/10439222 ... 6151048769]

I am working through about a dozen keyboards from this weekend's trip to Electronics Plus. The first I tore down was a NMB HiTek Space Invaders Black keyboard. We've seen this one before so more than anything this was practice for me in taking photos with a new flash (thanks Cindy!) and just seeing what I could do. Photo tips for future keyboard rounds welcome. Also please let me know if there is anything I missed.

30 photos total. Let's jump right in shall we?

The keyboard came from a government user. Surprisingly pristine for what I'm guessing by the date is a late 1980s keyboard. I did not clean it after picking it up:
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A photo of the back...
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...and a close-up of the label:
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Space Invader key caps tend to pull the switch top with them. It goes right back in fortunately. To get just they key cap hold the hey puller upright, tilt 45 degrees to the left or right, and pull gently. The spring and the "praying hands" contacts are clearly visible. PBT dye sublimated key caps, decently thick.
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This is a regular five pin AT keyboard. I have not yet plugged it in - forgot to bring home an AT-PS/2 adapter.
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Just over 48cm wide...
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...21cm deep...
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...and weighing in at 1593 grams. Not super heavy like a Model M but not super light.
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Disassembly begins with removing these seven screws.
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Lifting carefully, the front of the keyboard case remains on the desk.
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More photos below!

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XMIT
[ XMIT ]

23 Feb 2015, 04:11

Removing the front of the case reveals a single sided PCB, a relatively simple controller board, and plate mounted switches.
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Remove a single screw to free the back of the case.
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The back of the case. I believe this, and the front, are also PBT.
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The base plate and PCB without the case.
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The rear of the PCB showing traces and solder mask. Each switch has four holes, so, I assume this keyboard is *not* NKRO. I do not see any signs of diodes.
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Key profile. The lower two rows are angled aggressively.
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Close up of the controller, a Motorla NMB86151164 microcontroller according to https://octopart.com/nmb86151164-motorola-15163564.
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Another switch close-up, with internal switch elements and plate mount visible.
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The springs, of unknown weight, are 17.36mm long...
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...and likely 2.5mm across, as they must clear a space 2.67mm across.
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Last edited by XMIT on 23 Feb 2015, 04:20, edited 2 times in total.

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XMIT
[ XMIT ]

23 Feb 2015, 04:11

The extra-large Enter key is well stabilized.
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These are cylindrical key caps.
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The switch pins are about 6.16mm apart in the X direction...
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...and 5.33mm apart in the Y direction.
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One switch removed, after about 15 minutes of fiddling. These are not fun to remove. Desoldering was the easy part with a good solder sucker but the plastic clips are tight and the space between keys is minimal. There was a screw holding this one switch in place.
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The "click" is tactile, and is a small plastic spring pin sliding along a bump in the back of the switch casing. The tactile bump has nothing to do with the actuation point of the keyboard. Ideally they are in the same spot but this requires the switch leaves to be calibrated correctly. (Experimenting with macro shots, I placed a magnifying glass in front of my camera's lens.)
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The same switch seen from the rear. No provisions for LEDs or diodes.
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The same switch viewed from the side.
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Switch internals viewed through the magnifying glass. The spring leaves also contain two pins each for soldering and come out fairly easily, though they bend easily and this throws off switch calibration (actuation point). In total each switch has six pieces: two leaves, a spring, a bottom case, a top slider, and a key caps.
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Finally, the PBT key caps are 1.26mm thick.
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Assembly is the reverse of disassembly. Thanks for reading!

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Mal-2

23 Feb 2015, 06:48

jsoltren wrote: (Experimenting with macro shots, I placed a magnifying glass in front of my camera's lens.)
That's all screw-on closeup filters really are, they just eliminate the need to hold them. If you're doing this a fair bit, a set of filters at smaller sizes (like 49 mm or 52 mm) won't set you back more than $50, and also will not affect the automatic functions of the camera the way an extension tube often does.

idollar
i$

23 Feb 2015, 07:02

This is what I call a VERY good report/review/documentation !
Thanks for sharing ;)

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XMIT
[ XMIT ]

23 Feb 2015, 19:46

I've updated the Google Photos link with three items:
- force required to achieve actuation point: about 45 grams.
- force required to go past actuation point and bottom out: about 75 grams.
- video of typing with audio. It really makes a great sound.

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Madhias
BS TORPE

23 Feb 2015, 19:54

Great idea with the arrows!

The sticker on the front is great, i would not get rid of it.

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Redmaus
Gotta start somewhere

23 Feb 2015, 20:02

That was a very good review I definitely like the photos that were taken.

So you said that the tactile bump does not occur at the same time that the keyboard actuates so if you were to compare this to a bucking spring or cherry mx keyswitch, which relates the most to the space invaders?

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XMIT
[ XMIT ]

23 Feb 2015, 20:28

Redmaus wrote: So you said that the tactile bump does not occur at the same time that the keyboard actuates so if you were to compare this to a bucking spring or cherry mx keyswitch, which relates the most to the space invaders?
The "tactile" mechanism and the "actuate" mechanism are completely independent on this switch. The former is the result of a plastic arm moving past a bump on the rear of the switch cover. The latter is the result of two "hands" coming together.

From the factory the switch is very carefully calibrated so that these things happen at the same time. But they are not guaranteed to do so! If one of the switch leaves bends (very easy to do) they will happen at different times. It is not like, say, Cherry MX Blue switches, where the click comes from a piece physically moving out of the way of switch leaves, or buckling spring, where the spring must bend in order to actuate the presser foot at the base of the switch.

In terms of key feel, I think this is most like a slightly stiffer clicky Alps. The click mechanism is not like Cherry MX Blue or buckling spring in functionality.

The difference between this and the linear Space Invaders is the presence of the plastic click arm. The linears simply do not have it.

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Redmaus
Gotta start somewhere

23 Feb 2015, 20:43

Ah. Thank you for the useful information. From the mechanism you described, these must have been very complicated to manufacture.

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XMIT
[ XMIT ]

23 Feb 2015, 21:40

Redmaus wrote: Ah. Thank you for the useful information. From the mechanism you described, these must have been very complicated to manufacture.
I think they were very simple to manufacture. Getting the bend on the spring just right was tricky, but once they did, they could stamp them out by the thousands. The switches are three injection molded pieces, two stamped plated metal pieces and a spring. They plate mount easily and the switch is closed easily. The part count is low.

The click mechanism doesn't seem all that durable. One of the switch tops (now moved to Pause/Break) doesn't click at all. But even that makes sense. The clicking was presumably added later. The linear switches are quite reliable.

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Muirium
µ

23 Feb 2015, 22:17

Classic find! I do like these space invader boards. I've got one quite like yours, black clicky switches, but ISO instead of big ass Enter. Mine's got an ABS case because it's fairly yellowed, while all the caps are still pearly white PBT. Anyway, they're a great board for banging away on something furious! The chocky, crunchy, meaty tactile click they have is a glory all itself.
No flaws in my clicky switches. Even after I sent springs flying while pulling all the caps, and bent one right out of shape, on reassembly everything still works just fine. I haven't noticed a difference between click point and actuation, but then again these are heavy switches so I pound it quite hard and wouldn't feel something as fine as a slight discrepancy. I can vouch for my model's NKRO, though. It's a sterling board. The caps remind me of Topre in shape as well as quality, including that sharp profile down front.

Thanks for the pictures of the innards and switch dissassembly. Saves me the bother! I keep using mine so often it's become a routine front line board and I never got around to pulling it apart again.

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Redmaus
Gotta start somewhere

23 Feb 2015, 22:36

A linear switch seems like a more durable option.

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Muirium
µ

23 Feb 2015, 22:41

Plenty of things seem one way and turn out another. Ask that pain in the ass Malcolm Gladwell!

In any case, I can assure you I have a hundred good clicky switches here, and NMB/Hi-Tek manufactured them just fine. It's a nice enough wee design.

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Muirium
µ

24 Feb 2015, 12:36

@jsoltren: Say hypothetically you wanted to chop the numpad off this board to make a TKL mod. Does the PCB look good for doing that? I'm thinking of getting another NMB for this purpose. My current one is in nice shape, so I'd rather spare it, but I did like the placement of its controller away from the numpad!

Basically, what I'm looking for is the whole section of the PCB that's right of where a TKL ends should simply be switches and LEDs, no chips. Then I could cut it off and join whatever I have to, to leave the TKL matrix intact. Like this:

http://deskthority.net/workshop-f7/cher ... t2610.html

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XMIT
[ XMIT ]

24 Feb 2015, 13:00

I don't have an authoritative answer. But from a quick glance it looks feasible. Maybe take a close look at:

https://plus.google.com/photos?pid=6118 ... 3095878795

The originals are high enough resolution so that you can trace individual lines on the PCB. That is on purpose.

The controller and all of the other fun stuff are above the main key area so the numeric keypad does not contain any logic, just LEDs and switches. I did not see any NKRO diodes on the board. Granted I did not lift the backing plate.

What I cannot tell you for sure without spending much more time is whether the board will need a rework for that. (By "rework" I mean "additional changes after cutting".) But even those are not too bad. Just carefully scrape away solder mask with a hobby knife and attach a wire with a little ball of solder. If anything it is much easier to do this sort of mod on a PCB backed keyboard than something with a membrane, where you need to fuss with copper conductive tape, silver paste, etc.

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Mal-2

24 Feb 2015, 13:27

jsoltren wrote: What I cannot tell you for sure without spending much more time is whether the board will need a rework for that. (By "rework" I mean "additional changes after cutting".) But even those are not too bad. Just carefully scrape away solder mask with a hobby knife and attach a wire with a little ball of solder. If anything it is much easier to do this sort of mod on a PCB backed keyboard than something with a membrane, where you need to fuss with copper conductive tape, silver paste, etc.
Just looking at your picture, it would appear jumper wires will be necessary. There seem to be some traces that route from the chip area directly to the tenkey area before looping back to the rest of the keyboard. That's the bad news.

The good news is that it shouldn't take very much scraping and soldering directly to PCB traces, since a whole lot of the jumper wire ends can be attached directly to the solder joints of the switches themselves.

This is a very good candidate for a TKL mod, I would think — and I do keep an eye out for them.

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Muirium
µ

24 Feb 2015, 13:40

Just what I wanted to hear! Thanks guys.

I doubt there's many keyboards so friendly to TKL chop out there they even have a dotted line for the saw! This is the next best thing. And a TKL space invader board would be awesome indeed.

A glimpse of what's to come:
Image
http://deskthority.net/workshop-f7/g80- ... t8486.html

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fohat
Elder Messenger

24 Feb 2015, 23:05

I love NMB Hi-Teks, especially the black ones, but I have gotten some old/dirty/worn ones that were really bad.

Also, I normally dislike plastic "ring" style key pullers, but it is essential that you grab the sides (never the corners) of Hi-Tek caps and pull straight up, for which the ring pullers are perfect.

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stratokaster

27 Feb 2015, 10:31

Mal-2 wrote:
jsoltren wrote: (Experimenting with macro shots, I placed a magnifying glass in front of my camera's lens.)
That's all screw-on closeup filters really are, they just eliminate the need to hold them. If you're doing this a fair bit, a set of filters at smaller sizes (like 49 mm or 52 mm) won't set you back more than $50, and also will not affect the automatic functions of the camera the way an extension tube often does.
That's true for cheap macro filters, but more expensive ones use 2-lens achromatic optical formula. Unlike their cheaper brethren, they don't cause additional chromatic aberration.

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XMIT
[ XMIT ]

02 Mar 2015, 15:45

It flies!
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Typing this post on the keyboard. It really is a delight to type on. Relatively light key feel, certainly lighter than the Cherry MX Blues to which I am so accustomed. The metal backplate gives it a solid feel. I don't like the tiny Backspace key. though, and would probably remap backslash/pipe to a second backspace (except that I often use that in the command line). The spacebar has a heavier spring and I like that. I may pop out the spacebar switches in my Cherry MX Clear keyboards and replace them with Cherry MX Tactile Gray.

The actuation point is *just above* the tactile point, meaning you hit it first. This is pretty consistent across all of the switches.

A great value for someone looking to try something different. I think elecplus has more!

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Muirium
µ

02 Mar 2015, 15:59

Lighter than blues? The very first time I tried my black space invaders, they struck me as light too. But then I checked by switching between boards a bit. Black space invaders are actually really quite heavy, yet somehow don't feel that way. They fly very nicely indeed.

Big Ass Enter is a problem layout because of how it swallows the extra key. ANSI and ISO have a whole extra key over there (backslash, either above or to the left of their respective Return) while Big Ass has no option but to shrink the Backspace key instead. Madness!

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