The Korry 389 is a series of illuminated pushbutton switches that are often used in aerospace and aviation applications. While there are many variants of the switch, we are focusing just one. The switch on this page is actually manufactured by ECE for Aerospatiale in 1994. It was commonly used in many of the flight deck control panels in the Airbus A330. ECE and Aerospatiale are no longer around, but modern variants of this switch are still manufactured by Korry (389) and Eaton (96182). Despite the various manufacturers, it is a standard switch and they are highly interchangeable. In modern applications and manufacturing, it will likely be referred to as the Korry Standard 389 Switch. There are several components that make up the actual switch assembly, first is the outer housing which actually mounts to the panel surface. The switch module is secured within the outer housing by two screws that rotate small metal flags that extend slightly out of the square holes on either side of the housing. As the screws are tightened from within the switch module, it secures it within the housing.
There is a connector block in the back of the housing that accepts pins from the actual switch module.
The switch module can be removed from the outer housing and replaced entirely or serviced outside of the panel.
The switch module is a self contained actuator with 4 individual microswitches, along with the indicators on the pushbutton surface.
On the back of the switch module are the pins that insert into the connector as the switch is inserted into the outer housing. The letters A-D represent the 4 individual microswitches and the numbers 1-3 represent the C/NO/NC pins for each microswitch. The pins numbered 4-9 are for the top and bottom indicator segments.
The illuminated pushbutton is a separate component that can be extracted and "hung" from the switch module once removed by a small articulating bracket, or can be removed entirely if needed. This is the piece that the user actually pushes to actuate the switch. The color gels and stencils for the switch illuminator text are also located inside of this component.
In the image below of both ECE and Eaton switches, you can see the pushbutton component removed and hanging from the switch modules. There are individual contacts for the top and bottom illuminated segments as well as sockets for the 4 incandescent indicator bulbs.
Modern Korry switches use LEDs for the indicators along with a protection and regulation circuit. However, these classic switches actually use incredibly small incandescent light bulbs. There are 4 total bulbs per switch, two for the top indicator segment, and two for the bottom segment. Taking apart the pushbutton component reveals the individual bulbs. The bulbs are #718 type incandescent and can be purchased online. They generally run at 5 V and draw around 0.75 W.
