Service manual

8-1
March 2000
Part No. 001-3139-502
BACKPLANE
SECTION 8 BACKPLANE
8.1 DESCRIPTION
The Multi-Net Voter shelf backplane contains
slots for RVMs and CDMs. The slot defines the mod-
ule’s address. The backplane provides for cRVM to
RVM Bus loading and distributes:
1. Power.
2. Voter Diagnostics Bus.
3. cRVM to RVM Bus.
4. cRVM and RVM Received Audio.
The backplane has active circuitry that distributes
the Voter Diagnostics Bus. The Voter shelves can be
linked together by connecting a cable from J1 of one
shelf to J2 of the next shelf.
8.2 VDM BUS LOADING
The VDM bus needs to be loaded at 75 ohms. A
resistor is added to each shelf to provide a 75 ohm
load. Therefore, the number of shelves times 75 ohms
equals the value of the resistor that must be installed
in each shelf at location R14.
8.3 SWITCH SETTINGS
S1 through S13
Section 1
On = cRVM/RVM common audio enabled.
Section 2
On = cRVM to RVM bus connection enabled.
Section 3
On = Load resistor for cRVM to RVM bus* enabled.
Section 4
Not Used.
*NOTE: Only one load resistor is switched in when
there is an RVM(s) connected to a cRVM. Refer to
RVM Section 5.
8.4 POWER CONNECTIONS
Table 8-1 POWER CONNECTIONS
WIRE NO. GAUGE COLOR DESCRIPTION
W100
W101
W102
W103
W104
W105
W106
12
12
18
18
12
12
18
Red
Red
Blue
White
Blue
Blue
Green
+5V
+5V
+12V
-12V
Ground
Ground
-5V