Federal Signal Corporation 310LD-MV, Installation And Service Instructions Manual, Page: 3 / 16

Figure 1.
-3-
A. GENERAL FEATURES.
The 310LD-MV intercom is a 2-way communications device
designed for light duty industrial applications. Nominal operating
voltages include 120/240 Vac, 50/60 Hz and 24 Vdc. Voltage changes
for the 120/240VAC are internally switch selectable and the AC line
is fused with a 1/2 ampere 250 volt type GMC fuse. The unit also
offers internally selectable balanced or unbalanced line operation,
transformer isolated audio inputs and internally selectable Master or
Slave mode configurations. A call button with remote call dry contacts
is also factory supplied in the unit. The 310LD-MV has a NEMA 1
enclosure and is a UL Listed and CSA Certified signal appliance.
MASTER MODE:
Each intercom can be configured as a Master unit (Push-to-Talk)
or a Slave unit (Push-to-Listen) by changing the MAS/SLA jumper
(J3) on the printed circuit board (see figure 1). The intercom comes
from the factory set in the Master (MAS) mode.
In the Master mode the intercom acts as an amplifier, constantly
broadcasting over its speaker any signal that it receives on the signal
lines. Holding down the Listen/Talk switch changes the unit from a
speaker to a microphone (see figure 2). The intercom will now t rans-
mit over the signal lines to additional intercom(s) also set in the
R6
C11
REPLACE
CM
TYPE
J2
240VAC
ONLY
SAME
SW1
FUSE
WITH
GMC-1/2
1/2A
CR1
+
J1
T3
120VAC
1
C2
C1
R1
CR2
P
K1
C5 C9
C4 C8
C7
R18
24VDC
CALL
IN/OUT
CONTROL
GROUND
CONTACT
SPEAKER
2001290 A
K2
R19
EXT
REMOTE
REMOTE
-
+
IC3
C21
T2
CR7
CR6
CR5
CR4
C13
J4
>BAL
>UNB
J5 R17
R16
Q3
CR3
R15
C14
>MAS
>SLA
J3
R12
R13
R14
S
J6
R11
R10
R3
R2
C10
Q2
R8
R9
R7
C20
C19
C18
C17
R34
J7
C22
O
CR8
R33
R31
R32
R30
R29
R28
R27
R26
R25
R21
R22
R24
R23
T1
C3 C6
Q1 IC1
C12
R5
R4
C16
IC2
C15
R20
V
L
W
I
T
C
H
S
K
R
250V
F1
H1
H2
TO SPEAKER
FUSE
CLASS I WIRING
120VAC/240VAC
SWITCH
TO SWITCH
MASTER/SLAVE
JUMPER
VOLUME
CONTROL
CLASS II WIRING
BAL/UNBAL
JUMPER(2)
290A3076