Mircom MA-792 Installation And Operating Instructions Manual
MODEL MA-792
APARTMENT INTERCOM AMPLIFIER
INSTALLATION AND OPERATING INSTRUCTIONS
LNOTICE
All information, document, and specifications contained in this manual are subject to
change to change without prior notice by the manufacturer.
©2006 by Mircom Technologies Ltd.
Printed in CANADA, April 2006
LT-329 Rev. 2
INTRODUCTION
The MA-792 is a communications amplifier designed for communication between handset type
apartment suite stations and lobby panels incorporating handsets or loudspeakers. It incorporates
facilities to control an electric door strike remotely from each suite station. Apartment installations
involving more than one entrance can be accommodated with the addition of one or more
MIRCOM RL-401B multiple-entrance relay units.
MA-792 SPECIFICATIONS
Power Input, Communication:16 VAC 0.3 A or 16-28 VDC 0.2 A
Power Input, Door Strike:3-24 Volts AC or DC, 3 Amps.
Power Output, Communication:300 mW into 45 Ohms
Power Output, Door Strike:3-24 Volts AC or DC, 3 Amps. Max.
Door Strike Timing:3-15 Seconds, Adjustable
WIRING SPECIFICATIONS
1.Twisted-Pair wiring is required from terminals 2 & 6 of MA-792 amplifier to suite stations. The
following conductor pairs also require twisted pair wiring for distances up to 1m (3 feet):
MA-792 Installation and Operating Instructions
M1/M2
M3/M4
M5/M6
For greater distances, Twisted-Shielded pair wiring is recommended.
Connect shields of shielded wires to terminal 'G' of amplifier.
2.Use adequate wire sizes in order to minimize resistance of each conductor. Refer to the
following wire chart.
WIRE CHART
Power Wires: Terminals - T1, T2, T3; L1, L2, L3, L4, L5, L6
Communication Wires: Terminals - 1, 2, 6; S1, S2, S3, S4, S5, S6; X1, X2, X3, X4; Z, Z1, Z2
Function Wires: Terminals - 9, P, A, R
DISTANCE POWER COMMUNICATION FUNCTION
(meters) (feet) WIRES WIRES
50 164 #18 (AWG) #22(AWG) #22 (AWG)
75 246 #16 #22 #22
100 328 #14 #20 #22
150 492 #14 #18 #22
200 656 #12 #18 #22
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MA-792 Installation and Operating Instructions
ENCLOSURES AND HOUSINGS
1.The amplifier and relay unit are normally mounted within the lobby enclosure. When the
enclosures are located outdoors, the amplifier and relay unit must be installed in a dry location
where the ambient temperature is maintained between 0 °C and 40 °C ( 32 °F to 104 °F).
2.For installation of lobby enclosures refer to instructions supplied with enclosures.
3.PS-3B transformers may be mounted within the enclosures or at the main fuse panel. Care must
be taken to locate transformers at least 12 inches away from the amplifier and the lobby
microphone.
Observe local electrical codes regarding the installation of Class-2 transformers.
4.Suite station handsets can be mounted on single gang electrical boxes.
SYSTEM WIRING
Refer to fig. 1 for system wiring required for single entrance application.
Figures 2 & 3 show optional dual entrance applications.
AC Door Strike Operation
For AC (buzzing) door strike operation, refer to fig. 4 for wire connections. Select transformer "B"
to suit the power requirement of the AC door strike. MIRCOM M-10 door strike requires the 8 VAC
output of a PS-3B transformer for operation and transformer "B" is not required. Adjust door timing
control for desired door open delay time.
DC Door Strike Operation
For DC (silent) door strike operation other than with MIRCOM M-10 door strikes, connect 16 VAC
to terminals T1, T2 of the amplifier and the required door strike supply voltage as shown in fig. 4.
The door fuse on amplifier will burn if the door strike current exceeds 3 A. Use of a higher capacity
fuse voids warranty.
OPTIONAL CONFIGURATIONS
Lobby Handset
Refer to fig. 5 for the required connections when using IS-92 handset in the lobby enclosure.
Dual Entrance Connections
1.See figures 2 & 3 for dual entrance wiring.
2.Connections marked 'V' are common conductors to all suite stations, wire as per basic
connection diagram, fig. 1.
3.Connections marked 'X' are wired as per basic connection diagram or optionally as shown in
fig.4.
4.Busy lamp outputs at terminals X1, X2, X3, X4 are solid-state drivers. Connecting inductive
loads or lamps rated in excess of 24 Volts / 50 mA may cause damage.
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MA-792 Installation and Operating Instructions
CONTROL ADJUSTMENTS
The MA-792 amplifier has three field adjustable controls located on the front:
Suite Volume- Controls the audio level from the entrance panel to the suite station.
Lobby Volume- Controls the audio level from the suite station to the entrance panel.
Door Timer- Controls the 'door-open' delay time from 3 to 15 seconds.
OPERATING INSTRUCTIONS
1.Depressing a call button at the entrance panel sounds a CALL TONE in the corresponding suite.
2.Resident replies by lifting the handset off the hook and speaking into the microphone, this allows
both the resident and visitor to speak and listen simultaneously.
3.Resident may admit a visitor by depressing door button on the Suite Station, this will activate the
electric door strike for a pre-set time.
4.In dual entrance installations, communication and door strike operation is automatically directed
to the entrance from which the call originated.
5.Operating the optional post office lock activates the door strike at the main entrance.
TROUBLESHOOTING HINTS
1. No Communication from Lobby to suite handsets:
a) Check Volume control settings on amplifier.
b) Check wiring from terminals 1, 2, & 6 of amplifier to suite stations.
c) Check Speaker and Microphone connections from entrance panel to amplifier.
d) Check for 16 VAC supply at terminals T1 & T2 of amplifier.
2. Low Volume from Lobby area and from suite:
a) Check Volume control settings on amplifier.
b) Check that additional handsets are not 'off-hook'. Red lamp on amplifier will illuminate whenever
a suite handset is lifted. If more than one handset is 'off-hook', volume will be reduced.
3. No Door Strike operation:
a) Adjust door timer control on Amplifier.
b) Ensure that voltage at T2 & T3 is the specified door strike voltage.
c) Check door fuse on amplifier. If necessary, replace only 3 Amp., 3AG type fuse.
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