NMB 725 SERIES

Early Three Post Switch

Gundams

Retooling

After a couple of years, the molds for the 725 series was retooled. The "Soap Dispenser" also known as "Gundams" was replaced with a more blocky style of slider. Production of the 725 series was to moved to Thailand. Moving production takes a lot of time and during the transition period, it's believed that new molds were also produced in the United States.

Later Production

After production of the NMB 725 Series moved to Thailand numerous other generations would be created following the Second Generation all the way up to the Fifth Generation. NMB produced not only keyboards under their own branding and styling but would supply keyboard modules and keyboards for OEM customers. 

Later production includes the following generations below:

• Third Generation

• Fourth Generation

• Fifth Generation

These generations each go into more detail with regards to the changes overall within each generation.

Switch Variations 

(See link for more variations above)

Linear

The Series 725 switch was designed as a linear type and was commonly found in early keyboards as well as those used with computer terminals. This switch is prelevant throughout the entire production run of NMB based keyboards.

Operational Force

(57.1 +/- 14.2 grams)

Tactile

Tactility is provided by the contact leaves. The contact leaves have an indentation on each arm which narrows the spacing between the two contact arms.  As the slider is depressed, the contact separator bar moves through this narrowing, pushing the contact arms apart before allowing the contacts to touch. This spring of the contact arms provides increased resistance generating tactility on both the down-stroke and upstroke, with the upstroke being slightly more pronounced. The contact separator bar within the slider is narrower than that of the linear variant. The return spring of the tactile variant is slightly shorter and has fewer active coils than that of the linear version. Tactile switches were introduced in the Second Generation of NMB keyboards until the end of the Fourth Generation of keyboards.

Clicky

The click is achieved by way of a plastic follower arm that runs inside a track integrated into the rear of the slider. When the slider is depressed, the follower or click arm travels up the track and over a ramp creating an audible click sound. This follower arm is plainly visible and accessible without needing to dismantle the switch. This arm also provides a small amount of tactility. in order to add the track added to the slider, the rear portion of the central guidepost in the lower housing had to be flattened on one side. The click variant uses the same spring and contact arms as those used in the linear version.

The clicky switch was introduced in the Second Generation of NMB keyboards until the end including the Fifth Generation of NMB keyboards. The design of the clicky switch is based on the latching/locking switch. The clicky switch was trying to emulate the buckling spring keyboard that IBM produced.

Operational Force

(75 +/- 10 grams)

Latching/Alternate Action

The latching or alternate action variant of the Series 725 switch is uncommon, only being found in a few earlier keyboards. The latching switch has two different versions. The first being introduced in the First Generation as a Gundam latching switch. The second version being introduced in the Second Generation with a one-square eye switch. The latching mechanism consists of a pivoting latch arm mounted in the lower housing that runs in a one-way track in the slider. The track design is heart-shaped and incorporates a series of ramps to ensure the latch arm is only able to travel in one direction. Once the switch is depressed, a central v-shaped block traps the latch arm in the depressed state. Pressing the switch a second time forces the latch arm to continue the one-way path and return to the released position. This heart-shaped track design is similar to that seen in other latching switch designs.

Spacebar

The spacebar variant exists as linear, tactile, and clicky versions.

They are identical to their standard counterparts of the same type other than the spring. The spring used in the spacebar variant is longer which results in an increase in the force required to depress the switch. These switches are often marked with a painted dot or different colour, presumably used to differentiate them from standard switches during production.

Operational Force

(85.6 +/- 14.2 grams)

LED Switch

The integrated LED variant of the Series 725 switch integrates a 3mm round LED into the lower housing that is visible through a circular window in the keycap. The LED can be physically located in either the NE or NW corner of the switch, but the only known windowed keycaps use the NE position. To accommodate the LED, the slider was designed with a tapered shape. Linear, tactile and clicky versions of the integrated LED switch exist.

Operational Force

(57.1 +/- 14.2 grams)

Model Number Overview

NMB keyboards have serial numbers on most keyboards including OEMed keyboards. The ending of the serial number normally dictates the type of switch that can be found within the keyboard. NMB keyboards normally stick to the listed serial number however there are sometimes deviations. 

-001 Linear

-002 Tactile

-003 Clicky

-004 Tactile 

-005 Unknown (Linear or Tactile)

-006 Unknown

After some time around later fourth generation, NMB stopped using this system and instead started using a different model system that was introduced. This was introduced for the RT-101 series of keyboards and later rebranded for the RT8XXX series of keyboards. All keyboards that contain an RT6XXX model number are dome with slider or contain MEMB within the FCCID.

Additionally, some keyboards have their language code that is added to the end of the model number for example" 

RT8756CFR

The C for clicky and FR for French

The following ending classification below works only with keyboards that have an RT8XXX model number:

-C Clicky

-W Windows Key

-T Tactile 

-L Linear 

-LC LinearClicky(Tactile)

+ BAE

Keycaps Overview

This section is to better provide more in-depth context around keycaps produced by NMB.

NMB keycaps follow the following keycap profile and the row that a keycap belongs to can be found underneath the keycap via the mold markings. The keycap profile for all keyboards are as follows:

Top of keyboard

4(Optional)

4

3

2

1

1

Bottom of keyboard

First Generation

The first generation of keycaps are pressure fit and work on any generation of switches. Fingers within the caps are thick all the way from the center to the outside of the cap. These caps are normally only found on NMB First Generation keyboards and the caps are shiny on all sides. 

Second Generation 

The second generation of keycaps are clip fit design. Alpha keycaps normally will contain the same fingerstyle as First Genernation keycaps which are thick all the way through the finger. Stabilized keycaps however normally have thinner plastic after the first initial few mm from the inside of the finger. The stabilized keycaps used the wire design where the stabilizer wire clips into the switch housing and the keycap rests on top of the stabilizer wire while being clipped into the switch.

All keycaps within the second generation have shiny sides all around.

Third Generation 

The third generation of keycaps are clip fit design. The third generation of keycaps introduced the rod stab design. This new design had many iterations and implementations. The sides of the keycaps in this generation initially started off being shiny but later on, in the generation changed the sides of the keycaps to matte. Along with the later caps in the generation having matte sides the keycaps also dropped the rod stab design for the wire stab that was introduced in the Second Generation.

Fourth Generation

The Fourth Generation starts in the Fourth Generation of NMB keyboard where NMB kept the thick font and changed to a thinner font. These keycaps are rough on all sides and continued to use the wire stab design for all stabilized keycaps.

Fifth Generation

This last generation is when NMB continued to use the thin font that was introduced in the latter half of the Fourth Generation of keyboards. This font continued until the end of production.

Stabilizers Overview

NMB used many different types of stabilizers over the entire production run of NMB keyboards. This section will overview each type and the system that each one uses.

Wire

These are the most used stabilizer option on NMB keyboards. The wire stab system was first introduced in the First Generation of NMB keyboards. These stabilizers use unique switches where a different bottom housing allows the wire to be clipped into the switch while being sandwiched between the plate and the wire clip. The bottom housing of stabilizer switches allows multiple wires to be attached for bigger keys including big enter keys found on AT keyboards. 

Rod Stab

This stabilizer system uses a dummy switch with a cylinder or cylinders located either on either side or another dummy switch. This allows a rod that's located on the keycap to slide up and down and stabilizing the keycap. This system is used with the Third Generation of NMB keyboards. This system can be found being mixed in with the Wire stabilizer system. 

Alps Like

This system of stabilizers was introduced in the Fourth Generation of NMB keyboards. The wire that is used in combination with clips that are molded into the keycap that needs to be stabilized. This system can be used with the wire stabilizers as they don't need to clip into the switch.

Plate Overview

NMB two different types of plates over the entire production run of NMB keyboards. This section will overview each type and the system that each one uses.

Both plates include a notch cutout on the North/Top of the switch to allow Linear and Tactile clip on the top of the switch from interfering with the plate. Without the notch, for the clip, the slider would not return properly.

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