TM 11-7025-234-23
Control Board (A4) Dip Switch Jumpers
Switch
Position
Description
Jumper
S1 & S2
Scrambler Select
Selects one of four scramblers according to truth
table below:
S1
S2
Scrambler
--
--
OFF
Normal
OFF
OFF
ON
Self-Sync
ON
OFF
CCITT
ON
ON
V.29 (Auto Selected in V.29
Mode)
S3
OFF = Master
Master/Slave
(Multipoint
ON = Slave*
Mode Only)
*S3 ON selects a slave modem when S7 and S8
select multipoint configuration.
S4 & S5
Transmit Timing
This set of jumpers provides four choices for
transmit timing: internal, DA, BA, and DD as
shown below:
S5
S4
--
--
Timing
(INT) Internal Oscillator
OFF
OFF
(DA) External Clock Source
OFF
(BA) External Data Source
OOF
ON
*(DD) Looback Timing
ON
ON
*INTERNAL is forced for Modem Check or
Audio Busback. (Local loopback)
S6
Unattended
S6 = OFF gives UI or unattended initiate
capability based on signal quality.
Initiate
S6 = ON gives UI or no UI capability.
S7
Modem Con-
S7 & S8
S8
Configuration
figuration
V.29, V.27, V.26 Mode
OFF
OFF
OFF
ON
CC Mode (C Series Modem
Compatible)
Fast Train Mode (LSI Series
ON
OFF
Modem Compatible)
Multipoint*
ON
ON
*S3 ON selects a slave modem.
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