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Cherry M7 part number schema

The following page provides known details of Cherry M7 part numbers. See also the M4/M5/M6 Series schema.

See M7 examples for examples found to date.

Contents

Sources

This page lists only the parts found in official Cherry catalogues and advertisements. See parts for a parts list that includes unconfirmed types. The information below is sourced from the following:

See Cherry catalogues on the Deskthority wiki for copies of this literature.

Still required

Overview

This is the German series, originally manufactured alongside the US series with separate part numbers. The only useful known source of part numbers for Serie M7 is the Cherry Keyboards and Switches Catalogue 1982 (Germany), which covers a subset of the range. Four switches from the range are repeated in an undated, unidentified catalogue found by Brother Dragon (yab8433408) that—from the tiny fragment presented online—offers no insights.

The fine details of part number arrangement remain a mystery. There is still a permanently-zero position in all part numbers, and the stem design still appears not to have any formal representation in part numbers. Unfortunately the dearth of example part numbers, coupled with the sharp rise in options, makes this very hard to determine. In particular, there is only one tactile type, only one T mount type, and only one 10° type given in the 1982 catalogue.

Part number format

Part numbers follow this form:

M7S-0TAB

The positions are as follows:

Position Code Suggested meaning
1 M M: keymodule
2 7 7: Series number
3 S Subseries (1, 3, 4, 5, 6, 7 and 8); for details see the subseries table below.
4 0 This is always zero in known types, just as with the US-made switches
5 T Nominally this indicates the switch type; see the subtypes table below for details.
6 A Undefined
7 B Undefined

Subseries

The subseries are divided into three groups. Within each group, the subseries number indicates the number of contacts. The first subseries has one pair of contacts, and each related series after that has one extra pair. For example, M73 has one pair of contacts, while M74 has two pairs. M75 again has one pair, and thus M77 has two extra pairs (77 − 75 = 2), or three pairs in total.

The exact configurations are not known with complete certainty, because the relevant table in the 1982 catalogue is ill-conceived: it does not differentiate between inclusive (e.g. 2A+1B) and exclusive (e.g. 1A or 1B) contact arrangements, which is something you have to deduce and decode for yourself.

Subseries Design Contact pairs
M71 Centre-illuminated (possibly conceived as an extension of M4/M5/M6 series, and contemporary with M41) 1
M73, M74 Standard switches 1, 2
M75, M76, M77, M78 Complex design that supports up to two sprung-lead LEDs (for which there are dual-window keycaps) and up to four contact pairs 1, 2, 3, 4

The subseries are given in more detail below. The contact arrangements are educated assumptions based on the parts list, because it is not possible to be wholly certain about what Cherry’s table represents. M71 can be ordered with or without a lamp; it is assumed that the LED for M75–78 is optional as it is likely that many customers ordered these only for the extra poles, rather than the illumination.

Note that “1A, 1B” (for example) below means that you can choose between 1A (SPST-NO) and 1B (SPST-NC) while “1A+1B” (for example) denotes both contact pairs being present in the switch (in this example, SPCO BBM).

Subseries Contacts Action Illumination Stem Notes
M71 1A (1 pair) Momentary Lamp Straight, 0° The internal construction likely disallows the alternate action assembly
M73 1A, 1B (1 pair) Momentary, alternate None Straight, T; 0°, 10° Standard single pole switches
M74 2A, 1A+1B BBM (2 pairs) Momentary None Straight, 0° and 10°; T, 0° only Second contact pair occupies the space used by the alternate action assembly
M75 1A, 1B (1 pair) Momentary, alternate LED (single or dual) Straight, T; 0°, 10°
M76 2A, 2B, 1A+1B BBM and MBB (2 pairs) Momentary, alternate LED (single or dual) Straight, T; 0°, 10°
M77 3A, 2A+1B, 1A+2B (3 pairs) Momentary LED (single or dual) Straight, T; 0°, 10°
M78 4A, 3A+1B, 2A+2B BBM and MBB (4 pairs) Momentary LED (single or dual) Straight, T; 0°, 10°

Subtypes

Compared to the prior scheme, the subtype position has very few values.

Subtype Usage
1 Momentary
8 Alternate action
9 Only found in the part number of the one 2A+2B switch; previously it had been used for the one and only known 1A+1B switch.

Catalogue types

The following is the list of known types; most are from the 1982 German catalogue (1982/DE). The details are cited verbatim, although the column headings are simplified for space. The contact pairs column is added for convenience. Note that the M71 types have dual stems which, while being straight as noted, are not compatible with standard 12 mm keycaps.

Part no. Contacts Action Stem Angle Remarks Op. force (cN) Contact pairs Catalogue
M71-0037 1A momentary dual top & sides lighted 2-4 oz. 1 1979/US
M71-0100 1A momentary dual top & sides lighted 2-4 oz. 1 1979/US
1 A momentary without lamp 85±25 1 1982/DE
M71-0105 1 A momentary with lamp (5V) 85±25 1 1982/DE
M73-0100 1 A momentary 70±15 1 1982/DE
M73-0109 1 B momentary 108±28 1 1982/DE
M73-0110 1 A momentary 10° 70±15 1 1982/DE
M73-0112 1 A momentary for space bar Assembly unit 95±25 1 1982/DE
M73-0120 1 A momentary T 70±15 1 1982/DE
M73-0137 1 B momentary 150±50 1 1982/DE
M73-0176 1 A momentary with tactile feel max. 150 1 1982/DE
M73-0800 1 A alt. action 95±35 1 1982/DE
M74-0100 2 A momentary 95±35 2 1982/DE
M75-0100 1 A momentary 70±15 1 1982/DE
M75-0800 1 A alt. action 95±35 1 1982/DE
M76-0100 2 A momentary 95±35 2 1982/DE
M76-0800 2 A alt. action 95±35 2 1982/DE
M76-0890 1 A/1 B alt. action 95±35 2 1982/DE
M77-0100 3 A momentary 185±45 3 1982/DE
M77-0137 2 A/1 B momentary 95±35 3 1982/DE
M78-0100 4 A momentary 185±45 4 1982/DE
M78-0900 2 A/2 B momentary 95±35 4 1982/DE

See also