Service manual

10-1
March 2000
Part No. 001-3139-502
RECEIVER REVERT BOARD (RRB)
SECTION 10 RECEIVER REVERT BOARD (RRB)
10.1 GENERAL
The Receiver Revert Board (RRB) is designed
for either operation with the 800 MHz or 900 MHz
receivers. There is only one RRB per channel in the
system and it is installed in the Receiver Decoder
Module (RDM) at the local site containing the trans-
mitter portion of the voter. The RRB is a plug-in
module to an existing wire harness. The RRB oper-
ates in the temperature range of -30°C to +60°C
(-22°F to +140°F) with 10-90% humidity.
The RDM monitors for the presence of RS-232
data from the RVM to the MLM. If the RS-232 data is
lost, the RDM causes the RRB to switch, bypassing
the RVM and connects the RDM’s receiver directly to
the MLM. The RRB connects the receiver’s audio and
data directly to the MLM. The RS-232 data could be
lost due to an RVM failure, loss of link or power fail-
ure at the voter.
10.2 INPUT DATA
The RVM sends RS-232 Data at 9600 baud for
local MLM and at 2400 baud for a remoted MLM.
The RDM is not verifying the data but only looking
for the presence of data from the RVM.
10.3 INSTALLATION
The Receiver Revert Board (RRB) feature instal-
lation requires rewiring the RVM to MLM link and
verifying the switch settings of the RDM, RVM and
MLM. The RRB is located in the RDM (see Figures
10-5 and 2-8), for ease of explanation the RDM wiring
and switch settings are referenced.
Install the RRB into the RDM by plugging the
wire harness onto the RRB board. The revert feature
is enabled or disabled by RDM S1, section 6. Set S1,
section 6 "Off" to enable the revert feature.
10.3.1 RVM AUDIO AND RS-232 DATA
The Audio and RS-232 Data from the RVM to
the MLM need to be routed through the RRB located
in the RDM via the rear connector J585.
The Audio In is wired from the RVM, pin 21
(MLM Audio +) or J1, pin 1 on the backplane, to the
RRB via J585, pin 10. The Audio Out is wired from
the RRB via J585, pin 9 to the MLM at TB1, pin 4
(see Figure 10-1).
The RS-232 Data In is wired from the RVM, pin
23 (MLM Tx Data +) or J1, pin 3 on the back- plane,
to the RRB via J585, pin 12. The RS-232 Data Out is
wired from the RRB via J585, pin 11, to the MLM at
TB1, pin 6 (see Figure 10-1).
10.3.2 BAUD RATE
Verify the baud rate settings for the link in the
RVM, RDM and MLM (see Table 10-1).
Use 9600 baud for Direct Link where the RVM,
RDM and MLM are all located at the same location
(see Table 2-2 and Table 5-2).
Use 2400 baud for Remote Link where either the
RVM, RDM or MLM is at a different location.
Figure 10-1 RVM TO MLM LINK WIRING