Clear-Com MS-704 - Manual (Page 20)

M S - 7 0 4 / R M - 7 0 4 F O U R - C H A N N E L M A I N / R E M O T E S T A T I O N S 2 - 4
Figure 2-5: Stations Powered by Individual Channels
The illustration above shows the proper power wiring of a system powered by a
single MS-704. The remote stations connected to each channel are powered from
the intercom cable for that channel. In the case above, a short on any one line
will only take that channel down.
It is assumed that none of the power channels are connected together in the
external system wiring. However, if the power channels in a multiple-channel
remote station have been bridged by connecting the internal jumpers, those
channels would now have their power connected together. The system would still
work except that a short circuit on any of the connected channels would cause
them all to short circuit, thus taking more of the system down with a single short
circuit.
Connecting Intercom Channels on RM-704
Internal jumpers in the RM-704 allow you to defeat the power-channel isolation
of the unit, as described in the following procedure.
To connect two or more RM-704 channels together:
1. Please observe anti-static procedures. The circuit cards can be damaged by
static electricity. Please ground yourself and tools before touching any circuit
cards.
2. Remove the cover of the RM-704.
3. On the main circuit board, locate the J16 six-pin jumper.
The jumper is located on the center leftmost portion of the circuit card when
viewed from the front of the station. The label “J16” appears next to it.
Three jumper plugs are stored, unconnected, on the pins.
4. To connect two channels, lift one of the jumper plugs off of the pins, and
place it in the proper position, as shown in Figure 2-6.
FAIL SAFE POWER DISTRIBUTION SCHEME
WITH SINGLE-CHANNEL REMOTE STATIONS
BELT
PACK
2 Amp
Power
Supply
R
R
Ch A
Ch B
Ch C
Ch D THE 4 POWER LINES
Wall Station
Wall Station
ARE NOT CONNECTED
Wall Station
Wall Station
+30 Volts
for each
R
R
Intercom
Line
Wall Station
Wall Station
Wall Station
Wall Station
PACK
BELT
PACK
BELT
PACK
BELT
PACK
BELT
PACK
BELT
PACK
BELT
PACK
BELT
MS-704 Main Station