Clear-Com RM-704 User Manual
CLEAR-COM ENCORE
MS-704 FOUR-CHANNEL MAIN STATION
RM-704 FOUR-CHANNEL REMOTE STATION
INSTRUCTION MANUAL
MS-704/RM-704 Four-Channel Main/Remote Stations Instruction Manual
Part Number 810345Z Rev. 3
Legal Disclaimers
All Rights Reserved
Copyright © 2013 HME Clear-Com Ltd.
Clear-Com, the Clear-Com logo, and Clear-Com Concert are trademarks or registered trademarks of HM Electronics, Inc.
The software described in this document is furnished under a license agreement and may be used only in accordance with the
terms of the agreement.
The product described in this document is distributed under licenses restricting its use, copying, distribution, and decompilation/
reverse engineering. No part of this document may be reproduced in any form by any means without prior written authorization
of Clear-Com, an HME Company.
Clear-Com Offices are located in California, USA; Cambridge, UK; Montreal, Canada; and Beijing, China. Specific addresses
and contact information can be found on Clear-Com's corporate website:
www.clearcom.com
Clear-Com Contacts
Americas and Asia-Pacific Headquarters
California, United States
Tel: +1.510.337.6600
Email: CustomerServicesUS@clearcom.com
Europe, Middle East, and Africa Headquarters
Cambridge, United Kingdom
Tel: +44 1223 815000
Email: SalesSupportEMEA@clearcom.com
Canada Office
Quebec , Canada
Tel: +1 (450) 653-9669
China Office
Beijing Representative Office
Beijing, P.R.China
Tel: +8610 65811360 / 65815577
CONTENTS
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
The Clear-Com Concept. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Understanding the MS-704/RM-704 Main and Remote Stations . . . . . . . . 1-2
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Normal Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Intercom Power Status Lights (MS-704) . . . . . . . . . . . . . . . . . . . . . . . 1-5
Selecting Microphones and Enabling the Speaker. . . . . . . . . . . . . . . . 1-5
Listening to Intercom Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Talking on Intercom Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
The All-Talk Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Monitoring Main Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Sending and Receiving Call Signals . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Linking Intercom Channels Together (MS-704) . . . . . . . . . . . . . . . . . 1-6
The Announce Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Remote Mic Kill Function (MS-704). . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Hidden Front Panel Options and Adjustments. . . . . . . . . . . . . . . . . . . . . 1-7
DIP Switch Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
Hidden Adjustment Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Rear Panel Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
Intercom Line Termination (MS-704) . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
Short-Circuit and and Overload Conditions. . . . . . . . . . . . . . . . . . . . . . . . . 1-9
Summary of Front-Panel Lights. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Installation Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Intercom Line Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Line Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Fail-Safe Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Connecting Intercom Channels on RM-704. . . . . . . . . . . . . . . . . . . . . 2-4
Power Distribution and Short Circuit Protection . . . . . . . . . . . . . . . . . . . 2-5
Intercom Cable Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Portable Installation Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Permanent Installation Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Ground Isolation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Physical Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Description of Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Headset Connector (Front Panel) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Panel Mic Connector (Front Panel) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Intercom Line Connectors (Rear Panel). . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Program Input (Rear Panel) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Announce Output (Rear Panel) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
IFB/Hot Mic (Rear panel, 1/4 inch Phone Jack) . . . . . . . . . . . . . . . . . . 2-10
Accessory (Rear Panel, DB-15F) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
MS-704/RM-704 FOUR-CHANNEL MAIN/RE-
i
Internal Option Jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
IFB Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
Run/Test Mode Jumper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
Program Audio Feed to Announce Output Jumper . . . . . . . . . . . . . . 2-12
MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
MS-704 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
RM-704 Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
TECHNICAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . 4-1
MS-704/RM-704 Four-Channel Stations. . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
LIMITED WARRANTY. . . . . . . . . . . . . . . . . . . . . . . . . . 5-I
Warranty Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-i
Technical Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-i
Warranty Repairs and Returns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-ii
Non-Warranty Repairs and Returns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-ii
Extended Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-ii
Service Contract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-iii
Liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-iii
ii
MS-704/RM-704 FOUR-CHANNEL MAIN/RE-
Please read and follow
these instructions before
operating this product.
IMPORTANT SAFETY
INSTRUCTIONS
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Do not use this apparatus near water.
6. Clean only with dry cloth.
7. Do not block any ventilation openings. Install in accordance with the
manufacturer’s instructions.
8. Do not install near any heat sources such as radiators, heat registers,
stoves, or other apparatus (including amplifiers) that produce heat.
9. Do not defeat the safety purpose of the polarized or grounding-type plug.
A polarized plug has two blades, with one wider than the other. A
grounding-type plug has two blades and a third grounding prong. The
wide blade or the third prong are provided for your safety. If the provided
plug does not fit into your outlet, consult an electrician for replacement of
the obsolete outlet.
10. Protect the power cord from being walked on or pinched particularly at
plugs, convenience receptacles, and the point where they exit from the
apparatus.
11. Only use attachments/accessories specified by the manufacturer.
12. Use only with the cart, stand, tripod, bracket, or table specified by the
manufacturer, or sold with the apparatus. When a cart is used, use caution
when moving the cart/apparatus combination to avoid injury from
tip-over.
13. Unplug this apparatus during lightning storms or when unused for long
periods of time.
14. Refer all servicing to qualified service personnel. Servicing is required
when the apparatus has been damaged in any way, such as power-supply
cord or plug is damaged, liquid has been spilled or objects have fallen into
the apparatus, the apparatus has been exposed to rain or moisture, does
not operate normally, or has been dropped.
15. WARNING: To reduce the risk of fire or electric shock, do not expose
this product to rain or moisture.
Please familiarize yourself with the safety symbols in Figure 1. When you
see these symbols on this product, they warn you of the potential danger
of electric shock if the main station is used improperly. They also refer
you to important operating and maintenance instructions in the manual.
MS-704/RM-704 Four-Channel Main/Remote Stations
iii
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
This symbol alerts you to the presence of uninsulated dangerous
voltage within the product's enclosure that might be of sufficient
magnitude to constitute a risk of electric shock. Do not open
the product's case.
This symbol informs you that important operating and maintenance instructions are included in the literature accompanying
this product.
Figure 1: Safety Symbols
EMC AND SAFETY
The MS-704 and RM-704 stations meet all relevant CE, FCC, UL
(MS-704 only), and CSA specifications set out below:
EN55103-1 Electromagnetic compatibility. Product family standard for
audio, video, audio-visual, and entertainment lighting control apparatus
for professional use. Part 1: Emissions.
EN55103-2 Electromagnetic compatibility. Product family standard for
audio, video, audio-visual, and entertainment lighting control apparatus
for professional use. Part 2: Immunity.
UL 60065-7, CAN/CSA-C22.2 No.60065-3, IEC 60065-7 Safety
requirements.
And thereby compliance with the requirement of Electromagnetic
Compatibility Directive 2004/108/EC and Low Voltage Directive
2006/95/EC
This device complies with Part 15 of the FCC Rules. Operation is subject
to the following two conditions: (1) this device may not cause harmful
interference, and (2) this device must accept any interference received,
including interference that may cause undesired operation.
iv
MS-704/RM-704 Four-Channel Main/Remote Stations
Clear-Com manufactures
a wide variety of both
portable and fixed
installation units. All are
compatible with each
other.
OPERATION
INTRODUCTION
Congratulations on choosing this Clear-Com product. Clear-Com was
established in 1968 and remains the market leader in providing intercoms for
entertainment, educational, broadcast and industrial applications. The
ruggedness and high build-quality of Clear-Com products defines the industry
standard. In fact, many of our original beltpacks and main stations are still in
daily use around the world.
We recommend that you read through this manual completely to better
understand the functions of the MS-704 and RM-704. If you encounter a
situation or have a question that this manual does not address, contact your
dealer or call Clear-Com directly. Our applications support and service people
are standing by to assist you. (Refer to Chapter 5,“Warranty” for contact
information.) Thank you for selecting Clear-Com for your communications
needs.
THE CLEAR-COM CONCEPT
Clear-Com is a closed-circuit intercom system that consistently provides
high-clarity communication in high-noise and low-noise environments. A
basic system consists of a single- or multi-channel power supply or main
station connected to various single- or multi-channel remote stations, such as
beltpacks and loudspeaker stations.
Clear-Com manufactures a wide variety of both portable and
fixed-installation units. All are compatible with each other. Clear-Com
intercom systems can also interface with other communication systems and
devices.
Clear-Com is a distributed amplifier system; each main and remote station
houses its own mic preamplifier, headset or speaker power amplifier, and
signaling circuitry. Stations bridge the intercom line at a very high impedance
and place a minimum load on the line. The audio level always remains
constant, and does not fluctuate as stations leave and join the network.
Low-impedance mic input lines and specially-designed circuitry make
Clear-Com channels virtually immune to RFI and dimmer noise.
Clear-Com stations are interconnected with two-conductor, shielded
microphone cable. Portable stations are connected with two conductor cables
with 3-pin XLR connectors. One wire carries the DC power from a main
station or power supply to all remote stations, and the other wire carries 2-way
(duplex) audio information. The shield acts as a common ground. One
termination (per channel) is needed throughout the intercom network, and is
usually located in the main station or power supply.
MS-704/RM-704 FOUR-CHANNEL MAIN/REMOTE STA-
1-1
Clear-Com main stations, power supplies and certain remote stations each
Headset
Null
Pgm
Listen
Channel B
Null
Pgm
Listen
ChannelA
Null
Pgm
Listen
Channel C
Null
Pgm
Listen
Channel D
BCDA
Line
Length
Program
Interrupt
BCD
Auto-Talk
/Listen
B
C
DA
Talk Latch
Disable
B
C
DA
HS
Lim
B
C
D
A
Auto-Call
Speaker
On
Off
Volume
Channel DChannel CChannel BChannel A
Talk
Listen
Call
Talk
Listen
Call
Talk
Listen
Call
Announce
AllTalk
Link On
Mic Select
Panel
Headset
Mic On
Panel Mic
On
(Off)
(Default)
Panel Mic
Gain
Sidetone
Adjust
CH. B
CH.A
CH. C
CH. D
Short
MS-704
Program
Level
Program
On/Off
BCD
A
Long
(Short)
Remote
Mic Kill
Headset
Null
Pgm
Listen
Channel B
Null
Pgm
Listen
ChannelA
Null
Pgm
Listen
Channel C
Null
Pgm
Listen
Channel D
BCDA
Line
Length
Program
Interrupt
BCD
Auto-Talk
/Listen
B
C
DA
Talk Latch
Disable
B
C
DA
HS
Lim
B
C
D
A
Auto-Call
Speaker
On
Off
Volume
Channel DChannel CChannel BChannelA
Talk
Listen
Call
Talk
Listen
Call
Talk
Listen
Call
Announce
AllTalk
Mic Select
Panel
Headset
Mic On
Panel Mic
On
(Off)
(Default)
Panel Mic
Gain
Sidetone
Adjust
RM--704
Program
Level
Program
On/Off
BC
DA
Long
(Short)
MS-704
RM-704
4-Channel
Remote Station
4-Channel
Main Station
Auxiliary
Term
On
Off
On
Off
Term
On
Off
On
Off
Channel A
Output: 30V, 1.2A Continuous, 2A Peak
ELECTRIC SHOCK DO NOT
FIRE OR SHOCK HAZARD DO NOT
EXPOSE THIS EQUIPMENT TO RAIN
TO PREVENT
WARNING:
OR MOISTURE.
CAUTION:
REMOVE COVER. NO USER
SERVICEABLE PARTS INSIDE.
REFER TO QUALIFIED SERVICE
PERSONNEL.
MS-704
Hot Mic/IFB
Channel C
Channel B
Channel D
TO PREVENT
Program In
Announce Out
have an auxiliary program input with its own volume control, which allows an
external audio source to be fed to the intercom system.
Visual signal circuitry (call lights), a standard feature on all main and remote
stations, allows the user to attract the attention of operators who have
removed their headsets.
Figure 1-1: MS-704 and RM-704 Front Panels
1-2
Figure 1-2: MS-704 Rear Panel
Figure 1-3: RM-704 Rear Panel
UNDERSTANDING THE MS-704/RM-704
MS-704/RM-704 FOUR-CHANNEL MAIN/REMOTE STATIONS
MAIN AND REMOTE STATIONS
The MS-704 and RM-704 intercom stations are four-channel
microprocessor-controlled stations intended to work with other Clear-Com
party-line products. Both stations have a speaker, provisions for installing a
panel microphone, and a headset connector.
The MS-704 is a four-channel main station that contains a no-fail system
power supply. The RM-704 is a four-channel remote station intended to be
powered from the intercom line.
The following is a list of features found in the MS-704 and RM-704 intercom
stations:
• MICROPROCESSOR CONTROL: Most aspects of station operation
are under microprocessor control.
• REMOVABLE ACCESS PANEL: A removable access panel allows
access to most controls and option DIP switches.
• INDIVIDUAL CHANNEL CONTROLS: Each channel has individual
talk, listen, and call pushbuttons for each channel.
• MOMENTARY/LATCHING TALK BUTTONS: The talk buttons
have a momentary and latching action depending on how the button is
used. The latching function can be defeated with DIP switches.
• INDIVIDUAL CHANNEL ADJUSTMENTS: Each channel has
individual listen level controls, channel null adjustments, and program
feed level controls.
• MULTIPLE PROGRAM INPUTS: Multiple program inputs are
provided for local station monitoring and program feed to intercom lines
for local talent cuing (IFB).
• INTERNAL IFB (IFB - Interrupt Foldback of program feeds):
Program can be fed to each channel and interrupted (IFB) when a talk
function is active or when a call signal is received on that channel. An
internal jumper determines whether the IFB function is talk- or call-signal
activated.
• LINK FUNCTION (MS-704): The MS-704 has a link function that
places all channels into a common party-line at the push of a single
button.
• ALL-TALK: An all-talk button allows instant access to all channels.
• ANNOUNCE FUNCTION: An announce button allows external paging.
A set of relay contacts is provided to control an external system.
• PROGRAM FEED OVER STAGE ANNOUNCE: An internal jumper
allows the main program feed to be fed to the stage announce output. The
program is automatically interrupted when the announce button is
pressed.
• MIC ON/OFF SWITCH: A separate mic on/off push-button allows
turning the microphone off without upsetting the setting of talk switches.
• REMOTE MIC KILL SWITCH (MS-704): Front-panel switch allows
you to turn off all latched talks on remote stations and beltpacks.
• EXTERNAL MIC ON/OFF INPUT: An external logic input allows the
mic on/off function to be switched remotely.
MS-704/RM-704 FOUR-CHANNEL MAIN/REMOTE STATIONS
1-3
• EXTERNAL IFB and HOT MIC OUTPUT: A rear panel jack provides
direct connection to Clear-Com’s external IFB system such that the
station’s microphone can be used in the external IFB system. A buffered
unswitched output of the selected microphone is also available.
• SPEAKER ON/OFF SWITCH: The speaker may be turned on and off
with a front panel switch.
• SPEAKER DIMMING: Whenever a talk is active, the speaker output is
dimmed approximately 6 dB to prevent feedback.
• PANEL MIC GAIN: The preamplifier for the panel microphone has a
gain trim adjustment to allow field trimming. Adjustment of the panel
microphone gain also varies the frequency response of the preamplifier to
compensate for feedback when the microphone is used up close.
• POWER SUPPLY WITH SHORT CIRCUIT PROTECTION: The
MS-704 features redundant powering to remote stations by providing
separate short-circuit-protected power sources to each of the four
intercom lines. A short on one intercom line will not bring the whole
system down. Short circuit indicators are provided on the front panel for
each channel.
• HEADSET AUDIO LIMITER: The headset audio limiter restricts the
maximum audio level heard in the headset to protect the hearing of the
user. You can turn this feature on or off with one of the front-panel dip
switches.
OPERATION
Once installed and operational, the MS-704 and RM-704 intercom stations are
easy to operate. The following sections describe normal operation of the units,
use of controls available under the access panel, and abnormal operation of
the power distribution system.
Some of the following functions are exclusive to the MS-704 and are marked
as such.
NORMAL OPERATION
Normal operation of the MS-704 and RM-704 requires access only to the
front panel controls. The following is a brief description of how to use the
front panel controls in day-to-day operation.
There are option DIP switches and adjustment controls behind the access
panel in the lower portion of the front panel. To gain access to the switches
and controls, pull on the two latches on either end of the access panel and
remove it.
This section discusses the following subjects:
• Intercom power status lights
• Selecting microphones and enabling the speaker
1-4
MS-704/RM-704 FOUR-CHANNEL MAIN/REMOTE STATIONS
• Listening to intercom channels
• Monitoring main program
• Talking on intercom channels
• The all-talk function
• Sending and receiving call signals
• Linking intercom channels together (MS-704)
• The announce function
Intercom Power Status Lights (MS-704)
The four red short lights are failure indicators for each of the four intercom
lines. These lights will assist in locating a shorted or overloaded channel.
Within as little as ½ second of automatically cutting off power to an
overloaded intercom line, the MS-704 will attempt to turn power on again.
This allows momentary short or overload conditions to clear automatically.
Shorts are normally caused by miswiring or damaged cables. Overloads are
generally caused by connecting too many beltpacks and stations to an
intercom line.
Clear-Com’s advanced fail-safe design can sense the difference between a
short or an overload to optimally protect itself. Power is restored in as little as
½ second, depending upon whether there was a single or multiple short or
overload. The other channels continue to operate normally. The MS-704’s
advanced fail-safe circuit will bring the power back up even under full load
conditions. Front-panel lights indicate a fault on any of the four channels.
When the station is first turned on, all four short lights are normally off.
Selecting Microphones and Enabling the Speaker
To select the desired microphone, move the microphone select switch to the
appropriate position: either “panel” or “headset.”
The mic on pushbutton allows turning the microphone on or off. The mic on
pushbutton lights blue when the microphone is active.
The microphone will be turned on automatically whenever a talk function is
activated as it is assumed that you wish to talk. If one or more talks are active,
you may turn the microphone off without unlatching the active talks.
The speaker may be turned on and off with the speaker switch.
Listening to Intercom Channels
To listen to an intercom channel, press the listen button for the desired
channel. The listen button lights green to indicate that the listen function is on.
The listen level control (below the call button) for that channel is usually set
to full on position and the listening volume is set by the intercom volume
control to the left of the speaker.
MS-704/RM-704 FOUR-CHANNEL MAIN/REMOTE STATIONS
1-5
If several channels are being listened to at the same time, it might be desirable
to adjust the individual listen levels of each channel for the desired mix.
Talking on Intercom Channels
To talk on an intercom channel, press the desired talk button. Pressing and
holding the button will cause the function to be active only while the button is
held (momentary). Pressing and releasing the button quickly will cause the
function to latch on if it was off or turn off if it was on (latching).
The latching function can be defeated on an individual channel with an option
DIP switch beneath the access panel (latch disable DIP switch).
The button will be illuminated blue when the talk function is off and amber
when the talk function is on.
Another option allows the automatic setting of a listen function whenever a
talk is active (auto-listen DIP switch) for each channel.
The All-Talk Function
Pressing the button marked all talk sends the selected microphone to all
channels while the button is pressed (momentary only). This button lights
amber when pressed.
Monitoring Main Program
The main program input is the one on the XLR connector on the rear panel.
To listen to the main program in the speaker or headphone, adjust the program
level control just below the link and all talk pushbuttons.
Sending and Receiving Call Signals
To send a call signal on an intercom channel press the call button for that
channel. This is a momentary function.
If the auto-call option is selected for that channel, activating a talk button will
also send a call to that channel.
Receiving a call signal is indicated by a flashing red call button.
Linking Intercom Channels Together (MS-704)
A pushbutton allows the connecting of intercom channels B, C, and D to
channel A. The link pushbutton is latching in action. The link button
illuminates amber when all channels are linked together. In the latched
position, the entire station operates as one party line.
Tal k and listen buttons are non-functional on channels B, C, and D when they
are linked to channel A.
The Announce Function
1-6
A single pushbutton sends the active microphone’s audio to the announce
output on the rear panel. Any active talks are disabled while the announce
button is held. The announce button illuminates amber when held. Tal k and
MS-704/RM-704 FOUR-CHANNEL MAIN/REMOTE STATIONS
listen latches are not reset, but the microphone’s audio does not go to the
intercom line while the announce function is active. A set of relay contacts
are activated to control some external device.
There is an option which allows program audio to be fed to the announce
output. If this option is enabled, the announce pushbutton interrupts this audio
when it is pressed. Program audio feed to the announce output is selected by
setting jumper J11 on the main board to the on position.
Remote Mic Kill Function (MS-704)
When you press the remote mic kill pushbutton, the talk function shuts off for
every beltpack on all four channels. If the talk functions of a large number of
beltpacks have inadvertently been left activated, incidental noise and talking
can make it difficult or impossible to communicate on the party line intercom.
The remote mic kill button can be pressed to quiet the line in this situation.
Those needing to communicate can then set their talk functions to on as
needed.
Note: The remote mic kill button only functions if the MS-704 main
station is powering all of the stations in the system. Pressing the
button momentarily interrupts power to the other beltpacks and
stations in the system. If there are other power supplies or main
stations in the system, then the remote mic kill switch cannot
interrupt power and therefore cannot work.
HIDDEN FRONT PANEL OPTIONS AND ADJUSTMENTS
This section describes the option DIP switches and various adjustment
controls behind the access panel on the front panel. These option switches and
controls are usually set and not used in daily operation of the unit.
To gain access to these controls, pull on the two latches on either end of the
access panel and remove it.
DIP Switch Options
The unit is shipped with all DIP switches, except the Headset Audio Limiter,
in their default positions (up). The Headset Audio Limiter dip switch is
shipped in the down (on) position.
The following functions are enabled with DIP switches:
• HEADSET AUDIO LIMITER: The HS dip switch turns the headset
audio limiter on or off. Unless an especially high volume is needed, this
switch should be left in the on position to protect the hearing of the user.
• INTERRUPT ENABLE: Three DIP switches (B, C, and D) enable the
program interrupt function on channels B, C, and D. Program interrupt is
not available on channel A.
• AUTO-CALL: Four DIP switches (one for each channel) enable
automatically sending a call signal whenever a talk is active on the
enabled channel.
MS-704/RM-704 FOUR-CHANNEL MAIN/REMOTE STATIONS
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• AUTO-TALK/LISTEN: Four DIP switches (one for each channel)
enable automatically setting the listen function whenever a talk is active
on the enabled channel.
• TALK LATCH DISABLE: Four DIP switches (one for each channel)
disable the latching action of the selected channel.
• PROGRAM ON/OFF: Four DIP switches (one for each channel) enable
feeding the main program input to the selected intercom channel. The
main program input is the one on the XLR-3F on the rear panel.
The other four program inputs in the auxiliary connector feed their
respective intercom channels all of the time. The only way to turn off the
Auxiliary feed to a channel is to turn its individual control off.
• LINE LENGTH: Four DIP switches (one for each channel) allow the
optimization of the nulling circuitry for each channel. The default (up
position) is for lines less than 400 ft. (122 m). The down position is for
lines longer than 400 ft. (122 m).
Hidden Adjustment Controls
Various adjustments are available beneath the front access panel.
• PANEL MIC GAIN: This control trims the panel microphone
preamplifier gain to compensate for different uses of the station.
The unit is shipped from the factory in the minimum gain position (fully
counter-clockwise). This level matches the headset microphone level
when the panel microphone is worked up close. Raising the gain from the
factory setting should be done carefully, as too much gain will increase
the background noise in the intercom making it unusable.
• CHANNEL NULL ADJUST: The screwdriver-adjustable control
beneath each talk pushbutton marked null allows nulling of the hybrid
circuitry associated with each listen channel.
The amount of null in the listen circuitry varies with the length of the
intercom line. Adding or removing stations and intercom cable will
change the null. For optimum performance, the null control will need to
be adjusted each time there is some change in the intercom line wiring.
If a panel microphone and speaker is being used, the setting of the null
control is critical to prevent feedback.
To adjust the null control on a given channel:
1. Turn the sidetone adjust control just below the headset connector to
minimum.
2. Set a talk to the channel to be adjusted or send some program to the
channel and adjust the null control for the channel for minimum level
in the headphone. If the headset microphone is being used, hum or
gently scratch it for a continuous signal source to null on. If a good
null is not attainable, switch the long/short DIP switch for the channel
(to the far right of the hidden adjustments) to its opposite setting. Use
the setting that produces the best results.
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MS-704/RM-704 FOUR-CHANNEL MAIN/REMOTE STATIONS
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