Omron B3G-S series

Omron B3G-S series
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.

History

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.

Description

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

Variants include:

Short name	Model	Generation
Lock		1
Amber (Clicky)		2
Amber (Heavy)
Amber (Linear)
Cyan (Clicky)		2
White (Clicky, Tactile or Linear)	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.

Colours

	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]

Keyboards

Amber

Bondwell B310 (Amber for heavier keys)
Some Chicony KB-5160A
Some Chicony KB-5161A
Costar CSK-1101P^[7] (White for spacebar)
Great Wall KBD5^[8]
NTC KB-5060C ^[9]
NTC KB-6151-ER
Some NTC KB-6251
Omron B5GS-R101-620 (White for spacebar & enter)
System Instruments 101A8 (possibly White for spacebar)
Some Wang 725-7951
Wang WAK-1101S

Cyan

Datavue Snap 1+1^[10]
Some Focus FK-555^[2]
Some Focus FK-767 (Philips PM 3655 logic analyzer keyboard)^[6]
Some Unitech K959

White

Anritsu MS2601B Spectrum Analyzer keyboard (1st Generation)
Unspecified “JDL財務” (“JDL Financial”) keyboard (Clicky)^[3]
Some NCR 4950
Some NCR 4970^[11]
Omron SX-9100 (Linear)^[5]
Sony BVE-910 (Tactile)^[4]\
Sony M35 Laptop (Function Keys Only)
Sony SMC-3000G^[12]

Gallery

First generation

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

"Flat" white switch from an Anritsu MS2601B spectrum analyzer keyboard
"Flat" latching switch from an NEC 8313-12

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.