Fujitsu FKB4700

Fujitsu FKB4700
Part number	N860-4700-Tnnn
Manufacturer	Fujitsu
Layouts	ANSI, ISO
Keyswitches	Fujitsu Peerless
Interface	AT, PS/2

FKB4700 is a fairly common series of Fujitsu Peerless keyboards from Fujitsu.

Description

The rubber domes of the FKB4700 are found in two sheets: one for the function key row, and one for the remainder of the keyboard. To account for differing locales and feature sets, the FKB4700 has more trace contacts and domes than is necessary for all variants. Removing the case lid of a UK ISO keyboard reveals the supernumerary trace contacts and domes: this includes three domes below Delete/End/Page Down, and a trace contact for \ when ANSI enter is selected.

The switch stabilisers are similar to those on IBM Model M keyboards, but are not particularly effective, meaning that most stabilised keys need to be struck directly above the switch. The space bar also has a small wire spring that sits on one end; its purpose is not clear, but it may be intended to increase the resistance.

Extremely unusually for a membrane keyboard, the FKB4700 series features integrated lock LEDs. This is achieved by mounting the LEDs into the slider shaft plate, and by placing conductive rubber sleeves around the base of the LED pins. This allows the LEDs to make conductive contact with the top membrane without the need to apply solder.

Numbering inside the case suggests that the same case was used for keyboard lines numbered 1000, 4700 and 2931, but the other two product lines do not appear to exist.

Variants

In addition to branded and unbranded variants, FKB4700 has also been sold under other brands such as Triumph. The FKB4718 keyboard from Digital (p/n PCXAL-FA) bears the legend "FKB4700 series" and appears to be a rebranded PS/2 version; the plastic moulding of the FKB4718 is slightly different.^[1] The FKB4718 has been reported to be tactile, despite having the same switch components as any other Peerless keyboard:

It has Fujitsu Peerless keyswitches. This switch is tactile but some people reported that there's also a clicky variant of it but I'm not so sure about that. Therefore, this one does not give out the "click" sound.^[2]

Gallery

The following photographs are from an unbranded FKB4700-152 UK ISO keyboard with an AT connector. The controller IC is the sole place that the name "Fujitsu" appears; there is not even an FCC ID on the board to prove the manufacturer.

Fujitsu FKB4700-152
Case lid from below
Typical three-layer membrane set with curved backplate
Close-up of the membranes
Membrane layers overlaid with the dome sheets
Supernumerary trace contacts and domes
Controller IC
Integrated LED in num lock
Windowed keycap and LED slider variant
Integrated LED
Membrane contact tubes for integrated LED, to work around the inability to solder LEDs to membrane sheets