Four-tab clone
Four-tab clone refers to a shell design that is common to a wide variety of Alps clone switches.
Contents
Description
The majority of such switches are not branded; the only external clue as to the switch type is the mould numbering on the upper shell. The shells all follow a standard pattern, and with the mould numbering and branding removed, they would be virtually indistinguishable. The originator of this design is not known.
The lack of branding on early generations of Alps switches has led to four-tab clones being widely mistaken for genuine Alps SKCL/SKCM series and SKBL/SKBM series switches. The defining characteristic of a four-tab clone is that the shell is supported by the mounting plate from below by four small tabs; Alps themselves used two long tabs. No Alps Electric switches used the four small tabs, but some Alps clones did use long side tabs.
Two long tabs:
typically genuine Alps
Four small tabs:
a four-tab clone
Four-tab clones may be referred to as Simplified Alps Type II or XM. The former is an obsolete term with an unclear meaning, which is best avoided. The latter is a misconception that all four-tab clones are from the same manufacturer, of previously unknown name; "XM" stands for Xiang Min and thus the only switches legitimately referred to as "XM" are those manufactured by Xiang Min. Simplified Alps Type IV describes a specific switch, alps.tw Type OA2.
Examples
Families of four-tab clones include:
Unbranded
- Xiang Min KSB series
- Xiang Min KSBF series
- Taiwan Tai-Hao APC series (current)
- Hua-Jie AK series
- Hua-Jie AKF series
- Simplified Alps Type IV
Branded
Counterexamples
The following non-Alps switches do have the two long side tabs:
The following switches have incompatible leg spacing and are not compatible with Alps PCBs:
Recognition
Mould numbering
Mould numbering examination is a first step that allows for the recognition of certain switches. In particular, NW:A## numbering appears to always indicate Taiwan Tai-Hao APC series switches. N:A## and N:## typically indicates Xiang Min's non-LED switches.
NW:A## — Taiwan Tai-Hao APC series
N:A## — Xiang Min KSB series
N:## — Xiang Min KSB series
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Identification of specific switches requires that the switch be opened and the internals examined; care should be taken as the contacts are fragile and supported chiefly by the upper shell, and Alps clone switches are very difficult to reassemble while still soldered into the keyboard.
Internals
alps.tw classification is by switch internals. Some of the details are quite subtle, for example how much separation there is between the fingers of two-finger switches.
| Movable contact | Stationary contact | Leaf | Mould numbering | Designations |
|---|---|---|---|---|
|
Large | Wide steel | Alps | alps.tw Type OA1 |
|
|
_--_stationary_contact.svg)
|
_--_click_leaf.svg)
|
S:#A## | alps.tw Type OA2 variant A (Simplified Alps Type IV) |
|
|
Large | _--_click_leaf.svg)
|
S:## | alps.tw Type OA2 variant B |
|
|
Large | Wide steel | Unnumbered Alps | Simplified Alps Type III |
| One finger | 
|
Wide steel | NW:A## | alps.tw Type OA3: Tai-Hao APC series (older) |
| One finger | 
|
|
NW:A## | alps.tw Type T2: Tai-Hao APC series (newer) |
|
Large |
|
S:#A## | alps.tw Type T4 |
|
|
|
S:## S:#A# |
alps.tw Type OA4 |
|
|
|
|
Unknown | Hua-Jie AK-CN2 |
|
|
|
S:## NW:#,SE:# S:#A## |
alps.tw Type T1 |
|
|
|
SW:# | Xiang Min KSB-LE |
|
|
|
|
S:## | USw LABG01 |
|
|
|
NW:##,SE:## | USw LABI01 |
_--_movable_contact.svg)
|
_--_stationary_contact.svg)
|
|
NE:#,SW:# | Hua-Jie AK-CN2 (2) |
|
|
|
None | NE:#,SW:# | Hua-Jie AK-DN2 (2) |
|
|
|
N:A## N:## |
Xiang Min KSB-C (alps.tw Type T3) |
|
|
|
None | N:A## N:## |
Xiang Min KSB-N |
| ? | ? | ? | None | YH Alps clone |
| Two finger skinny taper | Small flat metal | Silver narrow leaf | None | YH-B Alps clone |
|
|
|
S:#A## S:A## |
alps.tw Type T8 |
| ? | ? | ? | N:{Kwanda logo}-A | Kwanda PB11C05 |
Incompatible leg spacing
At least one switch has legs spaced further apart than those of Alps switches and clones. The YH-B switch was sold as a replacement part for certain Guitar Hero controllers. It was previously referred to as the "YH-B Alps clone" before it became apparent that it is built to a revised physical specification. The images below show comparable "CS" and "YH-B" parts, very similar internally and externally, but with standard and incompatible leg spacing respectively.
Top; the switches are orientated 180° apart
Tops
Bottoms
Comparison with Alps SKCM Green
The third leg in these switches appears to be present only for physical support; it is not electrically connected to anything, and can be removed if not required. The CS type can be purchased with either two or three legs.
