Editing Mitsumi standard mechanical

{{TODO photo|more=true|reason=need pictures of additional variants}}

{{infobox dswitch
| image name        = Mitsumi standard mechanical.jpg
| manufacturer      = [[Mitsumi]]
| switch type       = Linear, tactile, latching
| actuation force   = 
| contact mechanism = [[Metal leaf]]
| switch mount      = [[Plate mount]]
| keycap mount      = [[Alps mount]], [[Mitsumi mount]], proprietary cruciform
}}

'''Mitsumi standard mechanical''' is a provisional name for a range of typical size discrete mechanical switches from [[Mitsumi]]. The name differentiates them from the [[Mitsumi miniature mechanical]] switch. The [[Alps mount]] version was formerly known as '''Mitsumi Alps clone''', even though it is not an [[Alps clone]] switch.

==Description==
Mitsumi standard mechanical switches have the same vertical and horizontal [[return spring]] orientations as the miniature mechanical switch. They have a simplified [[switchplate]] for the electrical contacts. A second pair of holes in the base implies potential support for a [[DPST]] arrangement.

Mitsumi branding appears on the base of the switch.

===Specifications===
No Mitsumi literature has ever been recovered. The Amiga 1000 keyboard specifications on the schematic diagram cite the following:

{| class="wikitable"
! Characteristic      !! Value
|-
| Operating force     || 50 gf
|-
| Maximum force       || 60±20 gf
|-
| Travel              || 4±0.5 mm
|-
| Off region          || 1.3 mm
|-
| Intermediate region || ~1.4 mm
|-
| On region           || 1.3 mm
|-
| Lifetime            || 10 M
|-
| Bounce time         || 5 ms maximum (at normal pushing)
|}

==Generations==
There are two generations of Mitsumi standard mechanical, differing primarily in size. The internals of the two generations are identical.

===Type 1===
Type 1 switches, the first generation, have a tall cruciform [[slider]] and an upper shell with a matching guide shaft. There are no standoff nubs on the base of the switch. All known Type 1 switches are linear, though some such as in the TONO Theta-7070 include late actuation tactile "linears" due to a stiff sensing leaf.

The latching variety has been found in the [[Commodore 64C]], introduced in 1986, while the original Commodore 64 keyboard used a curious switch with PCB protrusions for "legs". There is a suggestion here that the latching switch was introduced after 1982 (when the Commodore 64 was introduced) and by 1986.

The late linear variety can be found on old boards such as the TONO Theta-7070. It possesses a white cap, cruciform mount, and a sense leaf stiff enough to present tactility more than halfway down the keystroke. 

From the same board comes the yellow cap variant which is a light version of the linear switch. Any tactility from this sense leaf is negligible and it appears to be completely linear.

===Type 2===
Type 2 switches, the second generation, are simply a size reduction, likely to make them [[DIN-compliant]]. For maximum reduction in size, a negative mount slider was chosen, using the [[Mitsumi mount]]. They were also made with Alps mount sliders for Apple keyboards.

Type 2 switches are plate and PCB compatible with Type 1, and the switchplates are identical. Most momentary Type 2 switches are tactile, using two different approaches. The Mitsumi mount switches found in [[Commodore Amiga]] computers use an underslung return spring, just as with [[Mitsumi miniature mechanical]]. The Alps mount switches used by Apple in the [[Apple Extended Keyboard II]] use a modified contact actuator leaf that causes it to behaves like a [[tactile leaf]]. This latter design feels very tactile when tested loose, but under typing conditions the tactility is very faint.<ref name="MouseFan" /><ref name="rzwv" /> As a result of the low effective tactility, it appears that the actuator leaf adaptation was always overlooked.

==Evolution==
Type 1 switches all appear to have a blue switchplate. Type 2 switches are found with both blue and white switchplates. The Mitsumi-mount type 2 switches found in the Amiga 1000 have been documented as having blue switchplates<ref>geekhack — [https://geekhack.org/index.php?topic=19761.msg389989#msg389989 Amiga 2000 Cherry Keyboard]</ref>, while the same switch as shown below uses white switchplates of a design not seen elsewhere.

It would appear that blue switchplate were still in use at the start of the 1990s, but the point at which the colour changed to white isn't certain. Pictures from rzwv and MouseFan of the [[Apple Extended Keyboard II]] suggest that the change occurred around 1991; rzwv's 1993 Apple IIe keyboard with type 1 switches still has blue switchplates, but these switches may be old stock. The anomalous switchplate design below is found in switches being sold off via AliExpress, suggesting that the switches may be more recent, and the switchplate redesign may have occurred towards the end of the lifetime of the series. Presently there is not enough data to be certain of this.

==Variants==
The [[Tono Θ-7070 terminal]] keyboard has PCB code KAM-A66YN, suggesting KAM Type for at least part of type 1; it remains unknown whether the base type (e.g. KAM) covers alternate action and double action switches, or whether they would be (say) KAA and KAD Type respectively. "M" appears to denote "momentary" or "mechanical" and appears to be used in the linear metal contact types. The Mitsumi-made [[Commodore Amiga 1000]] keyboard has KCT-A89YC written on the PCB, suggesting that those switches are KCT Type. Comparing with miniature mechanical's KLM (linear) and KLT (tactile) types, KCM Type is implied for the linear type 2 switches, with KCT thus denoting the tactile types.

{| class="wikitable row-headings"
! Type !! Belongs to
|-
| KAM  || Type 1
|-
| KCT  || Type 2, tactile
|}

Known variants of this series are:

{| class="wikitable variants-table"
!                                                                !! Generation !! Mount     !! Switch type   !! Part number !! Notes
|-
| [[File:Mitsumi std 1 momentary -- top.jpg|175px]]              || Type 1     || Cruciform || Linear        ||             || 
|-
| [[File:Keys.jpg|175px]]                                        || Type 1     || Cruciform || Linear        ||             || As above, but with white shell<ref name="gh-Tono" />
|-
| [[File:No photograph.svg|175px]]                               || Type 1     || Cruciform || Linear, low force ||         || Yellow shell; used in pairs for wide switches and edge switches<ref name="gh-Tono" />
|-
| [[File:Mitsumi std 1 latching -- top.jpg|175px]]               || Type 1     || Cruciform || Latching      ||             || 
|-
| [[File:Mitsumi std 1 double action -- top.jpg|175px]]          || Type 1     || Cruciform || Double action ||             || [[Mitsumi standard mechanical double action]]
|-
| [[File:Mitsumi std 2MM tactile -- top.jpg|175px]]              || Type 2     || Mitsumi   || Tactile       || E25-33-137  || Anomalous switchplate
|-
| [[File:Mitsumi std 2MM tactile LED -- top.jpg|175px]]          || Type 2     || Mitsumi   || Tactile+LED   ||             || Anomalous switchplate
|-
| [[File:No photograph.svg|175px]]                               || Type 2     || Mitsumi   || Linear?       ||             || [[Monterey K7S]] normal keys
|-
| [[File:No photograph.svg|175px]]                               || Type 2     || Mitsumi   || Heavy linear? ||             || [[Monterey K7S]] space bar
|-
| [[File:No photograph.svg|175px]]                               || Type 2     || Mitsumi   || Latching+LED? ||             || [[Monterey K7S]] caps lock
|-
| [[File:Mitsumi std 2AM tactile -- top.jpg|175px]]              || Type 2     || Alps      || Tactile       ||             || 
|-
| [[File:Mitsumi std 2AM latching -- top.jpg|175px]]             || Type 2     || Alps      || Latching+LED  ||             || 
|-
| [[File:Mitsumi standard mechanical lock Alps mount.jpg|175px]] || Type 2     || Alps      || Latching+LED  ||             || 
|}

==Keyboards==
*[[Apple IIe Enhanced]] (type 1)<ref name="rzwv-IIe-Enh" />
*Some [[Apple M0110A]] keyboards (type 1)
*Some [[Apple Extended Keyboard II]] (type 2, Alps mount)
*[[CCE MC-4000]] (Exato IIe) (type 2, Mitsumi mount, likely at least two types; not confirmed)<ref name="Exato" />
*Some [[Commodore Amiga 1000]] keyboards (type 2, Mitsumi mount; from 1985)
*[[Commodore 64C]] (type 1 latching)
*[[Monterey K7S]] (type 2, Mitsumi mount; not confirmed — three different switch types; ca. 1986 example)
*[[Tono Θ-7070 terminal]] keyboard (linear with colourless shell; yellow low force; 1986 example)<ref name="gh-Tono" />
*[[Sears The Electronic Communicator 2]] (Type 1, 4 different types. Linear with white shell, Linear with black shell and LED hole, Linear DPST with white shell, Linear low-force with yellow shell.)
*[[Olympia electronic compact 2]] (Type 1, 3 different types. Linear with white shell, Linear with black shell and LED hole, Double action with white shell.)
==Disassembly==
The plate retention clips on each side are part of a plastic bar. This bar also holds down the top of the switch. To open the switch, insert a long, flat implement underneath the plate retention clip on one side, and gently lever the bar away until the top of the switch is released; it will move around 1 mm or so. Turn the switch over and do the same with the other side. This does not require a high amount of force and the switch should open cleanly.

<gallery widths=250 heights=187>
File:Mitsumi std 2MM tactile -- disassembly.jpg | Switch partially open
</gallery>

==Gallery==
<gallery widths=250 heights=187>
File:Mitsumi std -- linear switchplates.jpg                    | Linear switchplates: Type 1 momentary, Type 1 latching, Type 2 latching
File:Mitsumi std -- feel control.jpg                           | Type 1 momentary, Type 2 tactile (using underslung spring) and Type 2 tactile (using actuator leaf)
File:Mitsumi std -- leaf comparison.jpg                        | Standard switchplate (left) and tactile switchplate (right)
</gallery>

===Type 1===
<gallery widths=250 heights=187>
File:Apple M0110A switches.jpg                                 | Type 1 switches, including [[Mitsumi standard mechanical lock]]
File:Mitsumi std 1 momentary.jpg                               | Type 1 momentary
File:Mitsumi std 1 latching -- positions.jpg                   | Type 1 latching base, positions
File:Mitsumi std 1 latching -- base.jpg                        | Type 1 latching base, showing the older kana logo
</gallery>

===Type 2===
<gallery widths=250 heights=187>
File:Mitsumi std 2AM latching.jpg                              | Type 2 (Alps mount) latching
File:Mitsumi std 2AM latching -- positions.jpg                 | Type 2 (Alps mount) latching, positions
File:Mitsumi std 2AM latching -- base.jpg                      | Type 2 (Alps mount) latching, base showing newer Mitsumi logo
File:Mitsumi standard mechanical -- partially disassembled.jpg | Partially disassembled Type 2
File:Mitsumi std 2MM tactile -- opened.jpg                     | Anomalous switchplate version of Type 2 Mitumi mount tactile
File:Mitsumi std 2MM anomalous -- bag.jpg                      | Bag of Mitsumi mount Type 2 switches showing Mitsumi part number
</gallery>

==References==
<references>
<ref name="MouseFan">Mousefan – [http://mousefan.telcontar.net/image/ext2m.htm AppleExtendedKeyboardⅡ M3501 MITSUMI JAPAN 91] (Japanese only) Dated 2004-10-10. Retrieved 2015-07-29.</ref>
<ref name="rzwv">ちゃたりたいね — [http://kbd.rzw.jp/mechanical/apple_m3501_japan/ Apple Extended Keyboard II M3501 JAPAN MITSUMI軸] (Japanese only) Dated 2013-03-22. Retrieved 2015-07-29.</ref>
<ref name="rzwv-IIe-Enh">ちゃたりたいね — [http://kbd.rzw.jp/mitsumi_/apple_tdk-t12v/ Apple IIe MITSUMI十字白軸 リニア] (Japanese only) Dated 2014-02-28. Retrieved 2015-07-29.</ref>
<ref name="gh-Tono">geekhack — [https://geekhack.org/index.php?topic=87447.0 What is this, a tactile Mitsumi Type 1? Tono Θ-7070 terminal]</ref>
<ref name="Exato">1000 BiT — [https://www.1000bit.it/scheda.asp?id=1478 Computer's description]</ref>
</references>

[[Category:Mitsumi switches]]
[[Category:Keyboard switches with Alps mount]]
[[Category:Keyboard switches with Mitsumi mount]]
[[Category:Metal contact switches]]
[[Category:Linear switches]]
[[Category:Tactile switches]]
[[Category:Alternate action switches]]
[[Category:List of all keyboard switches]]