Clearcom MX-820 Matrix Switch

Clearcom 8 Channel Assignment (Routing) panel, VG condition.
Availability: 1 in stock
Manufacturer: Clearcom

This is an 8 x 20 Matrix assignment switcher with an easy to use series of mechanical crosspoint sliders switches.   The switcher is on a lightweight 2 RU panel, and all of the connections use simple push on Terminals.   

This information is from the Clearcom Manual for the MX-840A:


The MX-840A Assignment Panel allows easy setup and reconfiguration of Clear-Com intercom systems using a simple, graphical assembly of slide switches. It will switch up to 40 stations to 8 channels.


Each station has a slide switch associated with it. Simply slide the switch up or down to assign the sta- tion to one of eight party-line intercom channels. A transparent, removable front cover is provided so the assignment of each station cannot be inadvertently changed, yet still can be easily viewed. Locations above and to the right of the assignment switches are provided for labeling.

Power Monitoring

In any intercom system, problems can result from shorts caused by damaged cabling. In a large system, these defects can be difficult to locate. The MX-840A provides Power Monitoring LEDs to allow shorts and other power faults to be more easily located. The 8 green On LEDs and 8 red Fault LEDs monitor the power supplied to groups of stations. Stations 1 - 5 are associated with the first LED pair, stations 6 -10 are associated with the second LED pair, and so on. The LEDs will indicate "green" if power isOK, "red" if a station group is shorted or not connected, and "off" if no power is available on any station groups.

NOTE: Do not confuse the 8 LED pairs with the 8 channel connections. The LEDs are only associated with groups of stations, not with the 8 channels.

The MX-840A does not limit or control power -- it only monitors it. The power output capability of each power channel is the same as that of the power supply producing the power. 

Station Connections

Station wiring should consist of home runs from each Remote Station directly to the MX-840A Assign- ment Panel. The XLR pinouts from the Main and Remote Stations are as follows:

Pin 1 --- Ground (shield or drain wire)

Pin 2---+30VDC

Pin 3--- Audio

Connections to the MX-840A Assignment Panel can be made using the supplied 1/4 inch push-on con- nectors. Alternatively, the connections can be soldered. The ground leads from the Power Supplies, Main Stations, and Remote Stations should all be connected to the Ground Bus, which is a double row of 1/4 inch quick connect lugs. The +30 VDC leads from the Main Station or Power Supply channels should be individually connected to the +30 VDC Station Buses, as indicated in the diagram on the previ- ous page. Connecting the power for each group of stations (1 - 5, 6- 10, and so on) to the associated +30 VDC bus will allow the Power Monitoring LEDs to display any power faults. Audio and power con- nections are shown in the diagram on the previous page.