Clear-Com PS-704 User Manual

CLEAR-COM ENCORE

PS-704 FOUR-CHANNEL POWER SUPPLY

INSTRUCTION MANUAL

PS-704 Four-Channel Power Supply Instruction Manual

Part Number 810494Z Rev. 3

Legal Disclaimers

Copyright © 2013 HME Clear-Com Ltd.

All rights reserved.

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: [phone]
Email: [e-mail]

Europe, Middle East, and Africa Headquarters

Cambridge, United Kingdom
Tel: [phone]
Email: [e-mail]

Canada Office

Quebec , Canada
Tel: [phone]

China Office

Beijing Representative Office
Beijing, P.R.China
Tel: [phone]

CONTENTS

OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

The Clear-Com Concept. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Fail Safe Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

PS-704 Overall Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

Power Distribution and Short Circuit Protection . . . . . . . . . . . . . . . . . . . 1-5

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

Front and Rear Panel Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

Rear Panel Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

Front panel Indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

To Check Before Powering System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

Check Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

Check Intercom Cable Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

Final Tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Quick Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Intercom Line Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Line Termination (Rear Panel) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Program Input (Rear Panel) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Rack Mounting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Wiring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Single-Channel System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Multi-Channel System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Crosstalk Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Intercom Cable Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

PS-704 Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Troubleshooting Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

TECHNICAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . 4-1

PS-704 Four-Channel Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

PS-704 FOUR-CHANNEL POWER

i

LIMITED WARRANTY. . . . . . . . . . . . . . . . . . . . . . . . . . 6-I

Warranty Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-i

Technical Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-i

Warranty Repairs and Returns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-ii

Non-Warranty Repairs and Returns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-ii

Extended Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-ii

Service Contract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-iii

Liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-iii

ii

PS-704 FOUR-CHANNEL POWER SUPPLY

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.

PS-704 FOUR-CHANNEL POWER SUPPLY

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 PS-704 power supply meets all relevant CE, FCC, UL, 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

PS-704 FOUR-CHANNEL POWER SUPPLY

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.

The PS-704 power supply is a powerful, yet user-friendly unit that can serve
as the heart of a Clear-Com system. We recommend that you read through this
manual completely to better understand the function of the PS-704 and how to
optimize your system setup. Please pay particular attention to the section on
system wiring, as improper wiring detracts from the performance of the
system or causes system failure. If you encounter a situation or have a
question that this manual does not address, contact your dealer or call
Clear-Com directly at the factory. Our applications support and service people
are standing by to assist you. (Refer to Chapter 6: “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 both 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 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 system.
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 (or individually shielded multi-pair cable as required).
Portable stations are connected with two conductor cables with 3-pin XLR
connectors. One wire, connected to pin #2, carries the DC power from a main
station or power supply to all remote stations. The other wire, connected to
pin #3, carries the two-way (duplex) audio information. The shield, connected
to pin #1, acts as a common ground. One termination per channel is needed

PS-704 FOUR-CHANNEL POWER SUPPLY

1-1

throughout the intercom network, and is usually located in the main station or
power supply.

Clear-Com main stations, power supplies and certain remote stations each
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.

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.

DESCRIPTION

The Clear-Com PS-704 is a single rack space, one- to four-channel intercom
power supply which can provide up to 1.2 amperes per channel to operate
Clear-Com beltpacks and remote stations. This power is supplied to any or all
of four channels, and will support up to 40 beltpacks or 10 speaker stations.
Clear-Com’s new fail-safe design automatically shuts down the power to a
channel when a short circuit or electronic overload is sensed on that channel.
The other channels continue to operate normally. Once the fault condition is
removed, the PS-704's fail-safe circuit will bring the power back up, even
under full load conditions. LED indicators signal a fault on any channel. A
line-level program input offers a master input level. Individual program
selects, each with its own send level, are provided for each channel. Use of a
switching power supply allows the PS-704 to operate with any AC line
voltage from 100 volts to 240 volts AC at 50 Hz or 60 Hz. The metal chassis
and extra-thick front panel with integral rack ears maintains legendary
Clear-Com ruggedness.

1-2

FAIL SAFE POWER

An intercom power supply has special needs that are not met by traditionally
designed power supplies. An intercom power supply must work in adverse
conditions such as low AC line voltage, momentary shorts on the DC power
lines to the stations, and excessive peak loads during “power-on”conditions.
The following features are incorporated into the PS-704’s power supply:

• AUTOMATIC SHORT CIRCUIT PROTECTION: The PS-704’s
internal power supply checks each channel for a short or current overload.
If it detects a short the power supply will shut down that channel. A short
duration short circuit will not cause the power supply to interrupt power.

• AUTOMATIC OVERLOAD PROTECTION: The PS-704’s internal
power supply senses the difference between shorts and overloads. If an
overload is detected the power supply will shut down that channel. An
overload lasting a short period will not cause the power supply to
interrupt power.

PS-704 FOUR-CHANNEL POWER SUPPLY

• AUTOMATIC POWER RESTORE: The PS-704’s internal power

1

2

3

4

5

67

8

9

10

11

121314 15

16

17

18

19

20

5

10

15

20

0

0

0.5

2

4

7

14

20

Number of
seconds to
restore

Number of recent shorts or overloads

supply senses the difference between short-term and long-term shorts and
overload conditions. After the first few times a short or overload occurs,
the power supply will try to restore power after only 0.5 seconds. If the
short or overload persists or occurs repeatedly, the power supply will take
progressively longer (to a maximum of 20 seconds) to try to restore
power. This protects the power supply from damage due to overheating.
Once the short is removed, the channel will recover, even under a full load
condition. The automatic power restore times are shown in the following
chart:

• INDIVIDUAL CHANNEL SHORT CIRCUIT PROTECTION: Each
individual channel is separately overload and short circuit protected and
may draw as much as 1.2 amperes, though the total to both channels is
limited to 2 amperes. A short on any one intercom line will not bring the
whole system down.

• FRONT PANEL INDICATIONS: There are four overload indicators on
the front panel (one for each channel) and a power indicator for the power
supply. The overload indicators light steady when an overload or short
condition is detected. They blink if power to a channel has been shut off
as a result of an overload or short.

• PARALLELING MULTIPLE POWER SUPPLIES: Multiple power
supplies can be paralleled to increase system capacity. The PS-704’s
internal power supply will automatically detect the actions of other power
supplies during overloads and short circuits to restore power as quickly as
possible.

• MULTI-CHANNEL REMOTE STATIONS MAINTAIN THE
POWER LINE ISOLATION: The RM-704, RM-702 and KB-702 as

PS-704 FOUR-CHANNEL POWER SUPPLY

well as any two or four channel remote station or beltpacks are designed

Figure 1-1: Automatic Power Restore Times

1-3

to use the isolated power provided by the PS-704. Refer to Chapter 2‚

Send
Level

Overload

Program

OnOff

Channel A

Power

PS-704

Send
Level

Overload

Program

OnOff

Channel B

Send
Level

Overload

Program

OnOff

Channel C

Send
Level

Overload

Program

On

Off

Channel D

PROGRAM INPUT

LEVEL
ADJUST

CHANNEL D

TERM

D

ON

OFF

CHANNEL C

TERM

C

ON

OFF

CHANNEL B

TERM

B

ON

OFF

CHANNEL A

TERM

A

ON

OFF

PS-704

1

2

34

5

89 7

4-Channel
Power Supply

6

Output: 30V, 1.2A Continuous, 2A Peak

“Installation.”

• LOW NOISE CIRCUITRY: The direct current outputs of the PS-704
contain very little hum and noise. The PS-704 does not contribute to
audible noise in the remote stations and beltpacks.

Note: Power supply lines connected together at remote stations will disable

the individual channel short circuit protection feature.

PS-704 OVERALL DESCRIPTION

A brief description of the connectors and controls follows. (Refer to Figure
1-2.)

Figure 1-2: Front and Back Panels of PS-704

FRONT PANEL

1. POWER SWITCH: Switches the AC power to the PS-704 on and off. The adjacent green LED will illuminate when the power is on.

2. OVERLOAD INDICATORS: The respective red LED for each channel (A, B, C, D) will illuminate if the PS-704 senses a short or overload on that channel. When the fault is removed, the PS-704 will automatically reset and the LED will go out.

3. PROGRAM SEND: Slide switch on each channel (A, B, C, D) selects that channel to receive the program input coming into the PS-704. All channels receive the same signal from the rear panel program input.

4. PROGRAM SEND LEVEL: Trimpot adjusts the audio level of the program sent to its respective channel.

REAR PANEL

5. PROGRAM INPUT: Female 3-pin XLR jack accepts a balanced or unbalanced line-level input.

6. PROGRAM INPUT LEVEL: Adjusts the program level coming into the PS-704. Used with the program send level controls to achieve desired system program levels.

1-4

PS-704 FOUR-CHANNEL POWER SUPPLY

7. TERM. ON/OFF: Slide switch (one per channel) selects whether the PS-704 will provide termination for that channel. The default position is on.

8. INTERCOM LINE CONNECTOR: There are two 3-pin male XLR connectors per channel, wired in parallel or “looped-through.”

9. AC POWER SUPPLY INPUT: Connects to AC with an IEC cable. The
PS-704’s power supply will accept any line voltage between 100 volts and
240 volts AC @ 50 Hz - 60 Hz. It will automatically adjust to the line
voltage. There is no need for a selector switch or an external fuse.

Note: Power supply lines connected together at remote stations will disable

the individual channel short circuit protection feature.

POWER DISTRIBUTION AND SHORT CIR­CUIT PROTECTION

Depending upon how many shorts or overloads a channel has experienced
recently, the PS-704 will attempt to turn power on again within 0.5 to 20
seconds of automatically cutting off power to an overloaded channel. This
allows momentary short or overload conditions to clear automatically. If the
PS-704 cuts power off to one or more channels, it will indicate which channel
is affected by blinking the red overload light(s) corresponding to these
channel(s). This light will assist in locating the shorted or overloaded channel.
Shorts are generally caused by miswiring or damaged cables. Overloads are
generally caused by connecting too many beltpacks and stations to a channel.

The current requirements of Clear-Com remote stations and beltpacks vary
with model and use. A station that is simply on and idling in the circuit may
draw only a small amount of current.

The PS-704 provides DC power to operate Clear-Com beltpacks and remote
stations. The power is distributed between the four channels and will support
up to 40 1-Channel Beltpacks or 10 speaker stations or 12 headset stations.

OPERATION

Because the PS-704 is a power supply, its actual operation is very
straightforward. Some forethought as to system layout, station selection, and
cabling schemes is worthwhile, especially if the system encompasses multiple
channels, a large number of stations, long cable runs or any combination of
these. The only actual user-initiated operation of the PS-704 once it is
connected to the system is to switch the power on, check and set the
terminations, select the program sends, and adjust the levels. Any time the
system is initially powered up, it is a good idea to verify that none of the
overload indicator LEDs are lit.

FRONT AND REAR PANEL CONTROLS

In the following descriptions, the numbers in the left column refer to Figure
1-2 on page 1-4.

PS-704 FOUR-CHANNEL POWER SUPPLY

1-5