Monogram SMK derivative series

Monogram SMK derivative series
Switch type	Linear, Clicky, alternate action
Sense method	Metal leaf
Keycap mount	SMK cruciform (unconfirmed); Cherry MX mount
Switch mount	Plate mount

Monogram SMK derivative series refers to a series of SMK J-M0404 series clones and derivatives, distinguishable by the use of an unclear but readily identifiable monogram. There is a suggestion that these switches were manufactured in Hong Kong.<ref name="KBT" />

Nomenclature[edit | edit source]

File:USw LXBB01+RB01 branding.svg

Base branding is an unclear monogram

The base of each switch is branded with a monogram that appears to depict the letters 'C', 'S', 'C' and 'O', possibly in this order (reading outside to inside and top to bottom). These switches have never been found in any branded keyboard, so the identity of the manufacturer remains a mystery. Even the orientation of the monogram is not known for certain.

However, an interesting observation, based on an old NTC brochure <ref name="DT-A-III" />, can suggest that this switch, or at least the MX mount variant of this switch, went under the name of NTC mechanical keyswitch. The switch used in the NTC KB-5060 keyboard has the same appearance and the monogram symbol at the bottom.

Description[edit | edit source]

This series is a fairly close copy of SMK J-M0404 series. The types examined so far have two raised contact ridges along the crossbar of the stationary contact, just as with SMK switches; HTK switches only have one central raised area. The rear of the movable contact is copper colour in photos, suggesting that the whole contact is made of phosphor bronze; the front appears to be plated.

Variants[edit | edit source]

The series contains a number of different switch designs. Some have a keycap mount that appears to be SMK compatible, while others have a keycap mount that appears to be Cherry compatible. alps.tw wrote, "是台灣參考NEC軸而改良的嗎? 為了配合Cherry MX的鍵帽 ?",<ref name="KBT" /> the implication being that they are Cherry MX mount, which appears to be the case from photos of the switches in question (USw LXBB01 and LXRB01). Some switches with USw LX designations are likely to need reclassifying with USw LM designations once the keycap mount is confirmed. The clicky variant uses a white slider, has a click leaf and uses a Cherry MX keycap mount.

There are linear and clicky variants. The HTK switch is very similiar to the clicky variant.

Known examples include:

Designation	Keycap mount	Type
USw LXBW03	SMK?	Alternate action illuminable
USw LXBW04	SMK? (angled)	Alternate action illuminable
USw LXBB01	Cherry MX?	Momentary
USw LXRB01	Cherry MX?	Momentary, heavier weight?
	Cherry MX	Momentary, clicky

Alternate action variants[edit | edit source]

Two alternate action designs exist. One design (seemingly older) is a direct clone of SMK J-M0404 alternate action,<ref name="DT-A-II" /> while the other is a simplified design whose latching mechanism is exposed at the top to the ingress of foreign objects. Both types are notable for being illuminable: slots that run through the switch from top to bottom allow an LED with long legs to be fitted, reaching all the way down to the solder side of the PCB.