Alps KEH Series
Contents
Overview
KEH is a series of elastic contact (“integrated dome”) keyboard switches from Alps. Each self-contained, plate-mount switch contains a conductive rubber dome that sits over a pair of stationary contacts. There are two notable changes from the previous KED series with which these appear to be interchangeable:
- There is a coil spring above the dome, presumably in order to increase the amount of overtravel
- The shell clips together, allowing these switches to be opened for servicing
Despite being a rubber dome switch, KEH Series is linear.
In all known instances, the plunger is black. Typically the plunger is cruciform mount, but blade mount also exists in a General 2017PD printing calculator found from late 1983 or early 1984. Key travel in that example was measured as 3.5 mm.
It appears that SKER is the tactile equivalent to KEH.
Models
Switches
KEH model numbers are known only from Roland service manuals. As such, very little is known about the models.
Model | Type | Notes |
---|---|---|
KEH10903 | Momentary | No keycap |
KEH10003 | Momentary | 2-unit key kit |
The Roland JUNO-60 service manual clearly depicts KEH10003 as a kit containing the following parts:
- KEH10903 momentary switch
- KT3-2 2-unit ivory keycap
- CHC32801A plate-mount stabiliser guide pin module (incorrectly written “CHC3280/A” in the diagram)
- CK42602A cushion (sits over the guide pin)
Other Roland service manuals are less clear, but the JP-8 service manual describes KEH10003 as “Switch w/key top”.
Keyboards and keypads
Model | Type | Notes |
---|---|---|
KEH4A006 | 10-key pad | Used in the Roland MC-4; the “4” denotes a unit with 9–12 keys |
Replacement
Very few replacement switches are left, and while these switches are serviceable, damage such as a snapped plunger necessitates replacing part or all of the switch. System J Synthesizers in the UK have discovered that Futaba ML can be used as a replacement switch by way of a shim PCB. Their Roland TR-808 Start Stop Tap Switch replacement set can be used as a replacement to a failed KEH or KED switch.
Documentation
- Wizards of ALPS advertisement, Electronics, Vol. 54 No. 5, March 10 1981 (scanned by or for WorldRadioHistory.com)