Cherry PCjr Keyboard? - Early MX switches and DCS key caps

snuci · 25 Mar 2016, 17:35

I recently posted a couple of Cherry solid-state capacitive keyboards here and here and bought this one thinking that I was going to get another to see which of the two switches was more common (out of three keyboards in total). Turns out, it's a different type, even thought the internal construction is very similar (aside from the wireless difference).

I believe this is a Cherry brand IBM PCjr computer replacement keyboard. It has IR built in (hence the need for the batteries) but also has an RJ-11 interface (like an old phone plug). A switch on the back of the keyboard indicates it switchable from "Jr" to "Sr". There is no IBM PCsr unless they are referring to the IBM PC? Unfortunately, I don't have the RJ11 cable to try it. Now I just have to find an IBM PCjr.

This keyboard features early Cherry MX Black switches from mid-1984. They are really smooth. You will notice the space bar is also MX Black but the back side reveals a red dot that is only on the space bar key switch. I might have to take that apart as see what's inside.

The construction is almost identical to the two Cherry capactitive XT keyboards linked above except for the wireless IR and rear plate holes for the switch and battery cover. It is so close that I tried to fit it into the outer shell of one of the other XT keyboards but it is taller and a hair wider. This keyboard also has 84 keys vs 83 keys but uses an almost identical keypad footprint.

You may notice that the Caps lock key cap and some others have red indicator LED windows. These are non-functional because there are no LEDs behind them. This particular keyboard also has thin double-shot key caps marked "DCS 1-1". I think they may be PBT but I'm not sure what the numbering means. Being from 1984, this would be before Signature Plastics.

I'm surprised these keyboards are not more prevalent because the IBM PCjr chicklet keyboard and their IR keyboard were not hits. This keyboard is quite amazing compared to those. It must have been costly, originally. Anyway, here are some pics:

: Cherry PCjr MX - keyboard; Cherry PCjr MX - keyboard.JPG (317.95 KiB) Viewed 8258 times

: Cherry PCjr MX - back; Cherry PCjr MX - back.JPG (201.77 KiB) Viewed 8258 times

: Cherry PCjr MX - key caps removed; Cherry PCjr MX - key caps removed.JPG (297.59 KiB) Viewed 8258 times

: Cherry PCjr MX - back of PCB; Cherry PCjr MX - back of PCB.JPG (343.42 KiB) Viewed 8258 times

: Cherry PCjr MX - MX blacks; Cherry PCjr MX - MX blacks.JPG (304.75 KiB) Viewed 8258 times

: Cherry PCjr MX - PCB markings; Cherry PCjr MX - PCB markings.JPG (329.45 KiB) Viewed 8258 times

: Cherry PCjr MX - view of space bar area and no LEDs; Cherry PCjr MX - view of space bar area and no LEDs.JPG (347.19 KiB) Viewed 8258 times

: Cherry PCjr MX - space bar MX black switch; Cherry PCjr MX - space bar MX black switch.JPG (243.3 KiB) Viewed 8258 times

: Cherry PCjr MX - red dot on space bar MX black switch; Cherry PCjr MX - red dot on space bar MX black switch.JPG (254.52 KiB) Viewed 8258 times

: Cherry PCjr MX - ICs and dates (mid-late 1984); Cherry PCjr MX - ICs with dates.JPG (348.13 KiB) Viewed 8258 times

snuci · 25 Mar 2016, 17:36

More pics:

: Cherry PCjr MX - keyboard mechanism label; Cherry PCjr MX - keyboard mechanism label.JPG (240.99 KiB) Viewed 8247 times

: Cherry PCjr MX - Inside bottom plate; Cherry PCjr MX - Inside bottom plate.JPG (174.18 KiB) Viewed 8247 times

: Cherry PCjr MX - Bottom plate; Cherry PCjr MX - Bottom plate.JPG (159.56 KiB) Viewed 8247 times

: Cherry PCjr MX - keyboard model number; Cherry PCjr MX - keyboard model number.JPG (256.68 KiB) Viewed 8247 times

: Cherry PCjr MX - Jr/Sr switch; Cherry PCjr MX - Jr-Sr switch.JPG (174.07 KiB) Viewed 8247 times

: Cherry PCjr MX - key caps; Cherry PCjr MX - key caps.JPG (208.8 KiB) Viewed 8247 times

: Cherry PCjr MX - space bar stabalizer; Cherry PCjr MX - space bar stabalizer.JPG (227.88 KiB) Viewed 8247 times

: Cherry PCjr MX - DCS 1-1 key cap markings; Cherry PCjr MX - DCS 1-1 key cap markings.jpg (195.35 KiB) Viewed 8247 times

: Cherry PCjr MX - comparison (left) to solid-state capacitive key cap (right); Cherry PCjr MX - comparison (left) to solid-state capacitive key cap (right).jpg (231.96 KiB) Viewed 8247 times

jacobolus · 25 Mar 2016, 22:39

I would assume the Sr means XT protocol, or similar.

Thanks for taking all the great pictures!

Mid-1980s MX switches are so much nicer than mid–2010s MX switches.

My guess is that the spacebar has an extra heavy spring, and the marking is to make sure they soldered it in the right spot? Can you feel a difference?

Mattr567 · 26 Mar 2016, 04:29

Neat! that must be some of the earliest MX Blacks around, and the SP caps are interesting.

Engicoder · 26 Mar 2016, 04:46

Great pictures and great cleaning job as always.The Jr Sr switch is great.

The layout is interesting. Its slightly different from the IBM PC/XT layout, but identical to one of the Key Tronic XT layouts, right down to the led windows. Not sure if Key Tronic originated this layout.

Blaise170 · 26 Mar 2016, 05:06

Yeah I would have assumed this was Keytronic foam and foil if not for the Cherry marking. The LED windows are a dead giveaway for Keytronic 95% of the time.

jacobolus · 26 Mar 2016, 05:49

This was a keyboard made in the US. At what point did Cherry move all their keyboard production to Germany?

Blaise170 · 26 Mar 2016, 06:11

jacobolus wrote: This was a keyboard made in the US. At what point did Cherry move all their keyboard production to Germany?

Cherry still has American offices, it's totally possible that manufacturing has always occurred in Germany and Cherry Americas has just imported the products from their German factories.

Chyros · 26 Mar 2016, 12:38

Actually THOSE LED windows were also used by Hi-Tek/NMB in their earliest boards. The layout on those is identical as well. The Key Tronic font gives it away though. Key Tronic used uncoloured LED windows in the top right later that are extremely indicative of them.

Engicoder · 26 Mar 2016, 13:41

Blaise170 wrote:
jacobolus wrote: This was a keyboard made in the US. At what point did Cherry move all their keyboard production to Germany?
Cherry still has American offices, it's totally possible that manufacturing has always occurred in Germany and Cherry Americas has just imported the products from their German factories.

According to the Cherry website

April 17, 1953 Walter CHERRY establishes CHERRY Electrical Products in the basement of a Highland Park, Illinois restaurant.

1963 CHERRY establishes its first European operation in CHERRY Mikroschalter GmbH, West Germany.

1973 CHERRY introduces the Keyboard line.

snuci · 26 Mar 2016, 14:50

jacobolus wrote: My guess is that the spacebar has an extra heavy spring, and the marking is to make sure they soldered it in the right spot? Can you feel a difference?

I can't really feel a difference and I was going to try to take this and a normal switch apart to see if there is any difference but I suck at trying to take MX switches apart that are already mounted.

Blaise170 wrote: Yeah I would have assumed this was Keytronic foam and foil if not for the Cherry marking. The LED windows are a dead giveaway for Keytronic 95% of the time.

Perhaps the key caps were both made by Comptec (pre SP)? I can;'t figure out why there would be LED indicator windows without LEDs. If I paid money for such a keyboard, I would want LEDs there!

snuci · 26 Mar 2016, 15:15

This is from Cherry's website in 1997 (which is slightly closer to 1984):

U.S. Operations

Cherry Electrical Products
3600 Sunset Avenue
Waukegan, IL 60087-3298
Phone (847) 6 62-92 00
Fax (847) 6 62-29 90

Cherry Electrical Products Control Devices
40 Terrill Park Drive
Concord
New Hampshire
NH 03301
Phone (603) 224-4227
Fax (603) 224-5843

Cherry Semiconductor Corp.
2000 South CountyTrail
East Greenwich, RI 02818
Phone (4 01) 8 85-36 00
Fax (4 01) 8 85-57 86

European Operations

Cherry Mikroschalter GmbH
P.O. Box 12 20
D-91271 Auerbach/Opf.
Germany
Phone (0 96 43) 18-0
Fax (0 96 43) 18-262

Cherry Electrical Products Ltd.
Coldharbour Lane
Harpenden, Herts.
AL5 4UN England
Phone (0 15 82) 76 31 00
Fax (0 15 82) 76 88 83

Cherry Sárl
1 Av. des Violettes
94384 Bonneuil Cedex
Paris. Frankreich
Phone (1) 43-77-29-51
Fax (1) 43-77-20-84

Pacific Operations

Cherasia Limited
Block B, 14th Floor
North Point Industrial
Building
499 King's Road
North Point
Hong Kong
Phone (852) 25 65 66 78
Fax (852) 25 65 68 27

Hirose Cherry Precision Company Limited
(50-50 joint venture)
5-30-11 Shukugawara
Tama-Ku, Kawasaki
Kanagawa Pref. 214
Japan
Phone (81) 45-472-4411
Fax (81) 45-942-7101

Cherry Australia Pty. Ltd.
Unit 14
104 Ferntree
Gully Road
Oakleigh, Vic. 3166
Phone (03) 5 44 86 44

TVS Cherry Pvt. Ltd.
(50-50 joint venture)
205 Madhava Building
Bandra-Kurla Complex
Bandra East
IND-Bombay 400 051
Phone (022) 6 45 25 82 / 6 45 25 83
Fax (022) 6 43 82 97

jacobolus · 26 Mar 2016, 23:06

snuci wrote: I can't really feel a difference and I was going to try to take this and a normal switch apart to see if there is any difference but I suck at trying to take MX switches apart that are already mounted.

Pretty sure you need to desolder it.

What I meant about the Made in USA thing was, at some point (up through the 70s or something?) Cherry was entirely in Waukegan, IL. Then they moved their corporate headquarters to Germany, but I think most or at least many of the keyboards/switches were still being made in the US. Recently, I was under the impression that most or all Cherry MX switches are coming from Germany.

snuci · 29 Mar 2016, 00:51

Here are some pics with the two different types of Cherry MX Black switches taken apart.

The first type is the space bar key switch marked with a red dot from the factory. The second type is the "normal" one used on all of the other keys. Oddly enough, the space bar doesn't seem significantly different in weight when installed but the spring is definitely heavier when squeezing by hand when dismantled. The lengths are slightly different and I believe the gauge of the steel is slightly thicker on the space bar switch. The normal key turns are more numerous at the edges as well. I wonder if the "red dot" MX Black turned into the MX Grey?

I apologize for the dark pics but I just can't get the switch top plate and internals to display because of the black colour. They are identical internally and I could not remove the last plate inside the switch so I left it alone before I broke something.

Here's some pics:

: Cherry MX Black Normal 1; Cherry MX Black Normal 1.jpg (341.55 KiB) Viewed 7709 times

: Cherry MX Black Normal 2; Cherry MX Black Normal 2.jpg (328.82 KiB) Viewed 7709 times

: Cherry MX Black Spacebar 1; Cherry MX Black Spacebar 1.jpg (326.26 KiB) Viewed 7709 times

: Cherry MX Black Spacebar 2; Cherry MX Black Spacebar 2.jpg (339.26 KiB) Viewed 7709 times

: Cherry MX Normal close-up; Cherry MX Normal close-up.jpg (318.9 KiB) Viewed 7709 times

: Cherry MX Spacebar close-up; Cherry MX Spacebar close-up.jpg (301.89 KiB) Viewed 7709 times

: Cherry MX spacebar (left) normal (right); Cherry MX spacebar (left) normal (right).jpg (349.14 KiB) Viewed 7709 times

: Cherry MX spring spacebar (left) normal (right); Cherry MX spring spacebar (left) normal (right).jpg (317.75 KiB) Viewed 7709 times

ideus · 29 Mar 2016, 02:52

A very interesting layout with nice profile double shots, thank you very much for sharing.

ماء · 29 Mar 2016, 03:33

Nice matrix