Omron B3G-S series

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Omron B3G-S series
Omron B3G-S series.jpg
Manufacturer Omron
Product code B3G-Snnn(N)
Introduced 1986 or earlier
Supersedes Omron B3G series
Switch type Clicky, tactile, linear
Sense method Metal leaf
Pretravel 1.8±0.5 mm
Total travel 4±0.5 mm
Keycap mount Alps mount
Switch mount Plate mount

The Omron B3G-S series is a switch similar in style and internal design to Alps SKCL/SKCM series, generally assumed (but not proven) to be based on the Alps design. With its unique pin layout (three pins in a line at the rear) it is not a clone of the Alps switch, but unlike most Alps clones and copies, it does use a switchplate to contain the contact mechanism.


The switch supersedes the Omron B3G series; Omron cite the B3G as being discontinued in February 1988, with B3G-S___N as the recommended replacement.[1]

On some switches, "B3G-S" is followed by "JAPAN"; on others, "JAPAN" has been removed from the mould, suggesting that production was moved outside of Japan to somewhere like Taiwan.


B3G-S switches have both "OMRON" and "B3G-S" written on the top of the shell, allowing them to be easily recognised without needing to be de-soldered and removed from the keyboard.

The 1986 catalogue entry for B3G-S is subtitled 「DIN規格に適した全18.1mmのロープロタイプ」: the switch is noted as being DIN compliant.

The shells of some white-slider switches contained a slot for an LED; some keyboards used these switches without LEDs fitted.

There is a slightly smaller Omron keyswitch, provisionally termed the Omron Alps-style switch for its more Alps-like slider, that has the Omron branding on the bottom, and only two legs in the switchplate.

The switchplate in the B3G-S series is a partially sealed unit: the front panel affixes to the back panel using melted plastic lugs. The contact bridge fits so tightly into the back panel that it is virtually impossible to remove it. The centre leg is also fitted in such a way that it is impossible to remove it: the movable contact lug is above a square block of metal that is walled in on all four sides, with the leg protruding from a hole in the plastic. It is possible that the plastic is moulded in around the metal, as it does not appear possible to assemble the switch. No switchplate has ever been sighted fully disassembled. In comparison, the Alps switchplate is a simple sandwich of metal and plastic layers that can be manually disassembled and reassembled with very little damage.

The switchplate itself simply holds a very thin strip of a copper-coloured, ferrous alloy; the top of this strip is pressed against a static contact by the actuator leaf, by way of a plastic leaf on the switchplate front panel.


Variants include:

Short name Model Generation
Omron B3G-S flat white latching.jpg Lock 1
Omron B3G-S series -- amber.jpg Amber 2
Amber Heavy
No photograph.svg Amber Linear
Omron B3G-S -- cyan variant.jpg Cyan 2
Omron B3G-S white tactile.jpg White Tactile B3G-S100N 2

B3G-S series is divided up into seven sub-series. The nature of these sub-series is poorly-defined. The details are from the 1986 catalogue (pre-N models).

Original 動作に必要な力 押し切に必要な力 Description Replacement
B3G-S100 40±10 g 50±15 g 標準荷重 "Standard load" B3G-S100N
B3G-S200 60±15 g 70±15 g 高荷重 "High load" B3G-S200N
B3G-S300 Not replaced; 特殊対応 "Special handling"
B3G-S400 60±15 g 60±15 g 感触つき "With touch" or "With feel" B3G-S400N
B3G-S500 Not replaced; 代替機種なし "No alternative model"
B3G-S600 B3G-S600N
B3G-S700 B3G-S700N

There appears to be a conflict between B3G-S100N which is tactile, and the 1986 catalogue which implies that—out of B3G-S100, B3G-S200 and B3G-S400—that B3G-S400 is the tactile model. It appears that no further elaboration of the design was offered by Omron in the catalogue.


  Amber: Clicky; most common variant
  Cyan: Clicky[2] — the cyan version requires less force and is substantially less tactile than the amber version
  White: Clicky[3], tactile[4], and linear[5]; also used as the space bar switch in keyboards with amber switches.[6][7]



First generation

Research suggests that the original B3G-S design had a "flat" slider. A functional LED slot appears to have always been present.

Second generation

Part numbers of the form B3G-Snnn were superseded with B3G-SnnnN. It remains unclear whether the change in slider design corresponds to the change in part numbers. Another change that occurred at some stage was the introduction of a dedicated non-LED base, leaving a blind LED hole; later switches removed the redundant LED hole from the lid entirely. The blind LED hole can be recognised by the lack of a clip to retain the LED, and a thick shell wall around the hole.


External links


  1. Omron — 生産終了(予定)品/推奨代替品:オムロン制御機器 (Japanese) Retrieved 2017-01-08.
  2. 2.0 2.1 Sandy — FK-555 (Japanese) Dated 2004-05-29. Retrieved 2015-07-31.
  3. 3.0 3.1 MouseFan — OMRON スイッチ分解 (Japanese) Retrieved 2015-07-31.
  4. 4.0 4.1 Imgur — Sony BVE-910(OMRON white) Dated 2013-05-22. Retrieved 2015-07-31.
  5. 5.0 5.1 MouseFan — OMRON SX9100 のキーボード シリアル (Japanese) Dated 2004-04-15. Retrieved 2015-07-31.
  6. 6.0 6.1 Deskthority — Philips PM 3655 Logic Analyzer Keyboard
  7. 7.0 7.1 Deskthority — Costar CSK-1101P: Compact Layout, Omron Switches
  8. YouTube — OMRON SX-9100 B3G-S 白軸 リニア キーボード - YouTube Dated 2014-01-13. Retrieved 2015-07-31.