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Alps KCL/KCM series

Overview

KCL and KCM were Alps’s DIN-compliant redesign of KCC series. Following the split of series names into separate switch and keyboard series, they were renamed to SKCL and SKCM series switches and KFCL and KFCM series full-size keyboards.

KCL was introduced somewhere around 1983, and SKCL/SKCM was still on sale into the 2000s. The series included linear, tactile and click feedback; single and double action; momentary and alternate action; and illumination.

Design

LED switches

Momentary linear types generally all have a slot in the top for an LED. This arrangement is not possible with the alternate action, double-action and tactile and click types because the other mechanisms occupy the space taken by the LED. The main body of the LED is 2 mm × 5 mm, and Alps fitted LEDs around 7.1 mm tall that protrude just under 1 mm above the upper surface of the switch. The combination of size and front–centre position are what prevent the LED from being used in switches other than standard momentary linear; by comparison, SMK “second generation” has a circular LED hole in the corner that is only around 2.2 mm in diameter.

The front and rear of the LED each have a flange at the bottom, around 0.7 mm tall and 0.4 mm deep. This flange fits into a step in the shell that prevents the LED sliding out. It appears that the LED can nonetheless be removed while switch is still attached:

  1. De-solder the LED
  2. Push the LED outwards away from the switch, so that the flange clears the step
  3. Pull up on the LED to extract it

This process works fine with a loose switch, but has not been tested with a switch fitted to a mounting plate. The following diagram shows the approximate dimensions of the LEDs found in 1980s SKCLFM switches:

Momentary types with an LED fitted in the factory (F-subseries) also have two holes in the base for the LED terminals, and a recessed area in the front flap to provide clearance. Momentary types sold without an LED fitted used the standard base without provision for an LED. The difference between these two designs can be seen in the illustrations below.

View full-size image SKCLFQ (F-subseries with LED) and SKCLAR (A-subseries, no LED)
View full-size image Matching front appearance with LED removed from SKCLFQ
View full-size image SKCLFQ LED recess
View full-size image Base comparison
View full-size image Base detail of SKCLFQ
View full-size image Side view of SKCLFW
View full-size image Base comparison
View full-size image LED retention step

There is also a small difference with the length of the return spring between these particular SKCLAR and SKCLFQ switches: the SKCLAR return spring is around 1 mm longer than that of SKCLFQ.

View full-size image Internals comparison
View full-size image Return spring comparison

Note that both model numbers are only an assumption. The return springs and weighting differs also between the assumed SKCLAR (red LED) and a confirmed batch of SKCLFM (green LED).

Double action

Alps KCL/SKCL double action is known from Canon typewriters. These switches have two contact modules (“switchplates”), one with and one without its actuator leaf. The module without an actuator leaf is operated by a separate, arched actuator leaf in the plunger, similar to SCK switches. No full disassembly has been undertaken, but the switch has been partially disassembled, and can be seen in the following photos:

Japanese utility model S60-060841 depicts approximately how these switches function, although the bottom of the switch that provides the stiff stage two spring seems to be different in production.

In typewriters, the plunger is colourless. In the 1994 catalogue, one double action model is advertised, specifically model SKCLKB with operating forces of 90 gf for stage one and 500 gf for stage two. This is not necessarily the same model as found in typewriters.

Another model can be seen in the Bravoman arcade machine, advertised as the “ベラボースイッチ” (Bravo Switch). This has an amber plunger. Erwin wrote about them in blog entry ベラボースイッチ特集1(純正スイッチ用ボディ&キャップ製作). An illustration on his blog indicates its operation:

The details are not clear on whether a “big punch” is detected by rapid closing of both switch contacts, or simply by the second pair of contacts closing. The second stage of double-action switches is generally very stiff.

The following images are from aucfree.com; they are still live, but the site itself has died. The images appear to be from a Yahoo! Auctions listing (ID p628617598) from pipinbee, which ran from the 30th of August to 2nd September 2018. There appears to be no way to contact Yahoo! Auctions members even when logged in, and thus no way to ask for permission to use the photos. They are reproduced here as they are the only known clear photos of the switch model.

View full-size image View full-size image View full-size image

The locking tabs that hold the shell closed are not the full width, and the mould cavity number is in very small writing, but both of these characteristics match with double action switches found in Canon typewriters, suggesting that these are genuine Alps parts.

See also