Clear-Com AC-701 User manual

AC-701 TELEPHONE AND 2-WIRE INTERFACE
INSTRUCTION MANUAL
CLEAR-COM ENCORE

AC-701 Telephone and 2-Wire Interface Manual
© 2007 Vitec Group Communications Ltd. All rights reserved.
Part Number 810510Z Rev. 2
Vitec Group Communications, LLC.
850 Marina Village Parkway
Alameda, CA 94501
U.S.A
Vitec Group Communications
7400 Beach Drive
Cambridge Research Park
Cambridgeshire
United Kingdom
CB25 9TP
Vitec Group Communications
Room 1806, Hua Bin Building
No. 8 Yong An Dong Li
Jian Guo Men Wai Ave
Chao Yang District
Beijing, P.R. China 100022
® Clear-Com, CellCom/FreeSpeak and the Clear-Com Communication Systems logo are registered trademarks of The Vitec Group
plc.

AC-701 TELEPHONE AND 2-WIRE INTERFACE i
CONTENTS
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Balancing the Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Additional Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Phone Hold. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
TECHNICAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
AC-701 Telephone and 2-Wire Interface Technical Specification. . . . . . . . . . 2-1
LIMITED WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-I
Warranty Period. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-i
Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-i
Warranty Repairs and Returns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-ii
Non-Warranty Repairs and Returns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-ii
Extended Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-ii
Liability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-iii

AC-701 TELEPHONE AND 2-WIRE INTERFACE
ii

AC-701 TELEPHONE AND 2-WIRE INTERFACE iii
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. Only use attachments/accessories specified by the manufacturer.
10. 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.
11. Unplug this apparatus during lightning storms or when unused for long
periods of time.
12. 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.
13. 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 station is used improperly. They also refer you to important
operating and maintenance instructions in the manual.
Please read and follow these
instructions before operating
this product.

AC-701 TELEPHONE AND 2-WIRE INTERFACE
iv
Figure 1: Safety Symbols
EMC AND SAFETY
The AC-701 Telephone and 2-Wire Interface meets all relevant CE and FCC
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.
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.
The AC-701 is intended for use on closed/PBX type telephone exchanges.
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 main-
tenance instructions are included in the literature accompanying
this product.

AC-701 TELEPHONE AND 2-WIRE INTERFACE 1-1
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, 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 AC-701 Telephone and 2-Wire Interface is a powerful, yet user-friendly unit
that can serve as a versatile interface between Clear-Com Encore Party Line
systems and 2-wire and telephone lines, as well as 3 and 4-wire systems. We
recommend that you read through this manual completely to better understand
the functions of the AC-701. 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 Warranty chapter for contact information.) Thank you for
selecting Clear-Com for your communications needs.
DESCRIPTION
The Clear-Com AC-701 is a versatile, active hybrid device that interfaces the
Clear-Com intercom system with a variety of other communication systems.
These include two-wire, three-wire, and four-wire telephone type systems,
carbon systems, and other closed-circuit intercom systems. The AC-701’s front
panel controls include a Mode Select switch, Transmit and Receive level gains,
and A and B Balance controls.
Figure 1-1: AC-701 Front Panel
Figure 1-2: AC-701 Rear Panel
The AC-701 rear panel has connections for the party line/power supply and the
telephone line receive and transmit.
Tel/2-Wire
Tel/2-Wire
Interface
Interface
AC-701
AC-701
Off
Phone
Hold
Headset
3/4
Wire
2
Wire
B Bal.
A Bal.Receive
Transmit
Clear-Com
Line
BP-1
BP-2
Transmit
BP-3
BP-4
Receive
1

AC-701 TELEPHONE AND 2-WIRE INTERFACE
1-2
SETUP
1. Connect the AC-701 to your Clear-Com system via the connector marked
‘Clear-Com Line’ on the rear panel, using standard two-conductor shielded
mic cable. The pin assignment on this 3-pin, XLR-type female connector is:
• Pin 1: Common
• Pin 2: Power
• Pin 3: Intercom audio
2. Select your mode of operation with the Mode Select switch: 2-wire, 3-wire, or
4-wire. The 2-wire mode is typically used with telephone-type carbon
systems.
The 3-wire mode is used with separate transmit and receive lines with a
common ground. This mode “looks” like a carbon headset, and can be used
to plug directly into the headset jack of a carbon system (such as a TV
camera).
The 4-wire mode is used when you have separate transmit and receive pairs.
Note: In the 3/4-wire mode, the B Balance control is not operative.
3. Connect the AC-701 to the external communication system via the rear panel
binding posts.
2-WIRE: Connect the AC-701 to all two wire systems using only the top
two binding posts (the red ones).
3-WIRE: For 3-wire systems, jump the two black binding posts together for
the common ground. Connect the red binding post marked “transmit”’ to
the portion of the circuit that the AC-701 sends signals on, and the other red
binding post (marked “receive”) to the portion of the circuit that the AC-701
is to receive signals from.
4-WIRE: For a 4-wire system, use all four binding posts: a red and black pair
for the transmit, and a red and black pair for the receive.
BALANCING THE INTERFACE
Note: Before balancing the system, be sure that the connections to both
Clear-Com and the external communication system have been made.
Balance cannot be achieved unless both systems are connected. Balance is
obtained with a built-in test tone via the A and B Balance switches.
2-WIRE MODE BALANCING: If your Clear-Com system is supported by a
main station with a master level control, turn the master gain control on the
Main Station fully counterclockwise. Newer Main Stations and Power Supplies
do not have a master gain.
1. Turn both gain controls on the AC-701 to the 10 o’clock position.
2. Plug a standard Clear-Com headset into the 4-pin XLR-type connector
marked “Headset” on the AC-701 front panel.

AC-701 TELEPHONE AND 2-WIRE INTERFACE 1-3
3. While listening on the headset, push the A balance momentary switch and
adjust the A balance trimpot for minimum tone in the headset. Repeat this
procedure with the B balance switch and trimpot. If the unit starts to
oscillate or motor-boat, back off both gain controls slightly and re-balance.
4. Disconnect the test headset.
3-/4-WIRE MODE BALANCING: The procedure is the same as for the 2-wire
mode, except the B balance is inoperative.
ADDITIONAL NOTES
1. The test tone levels heard in the system are affected by the Transmit and
Receive gain control settings.
2. Attempting to get too much gain from either system can cause instability and
oscillation.
3. If you are interfacing to a TELCO line and cannot obtain a satisfactory null
on the B balance, the value of capacitor C39 should be increased. Your
authorized Clear-Com dealer can try adding from .05 uF to .1 uF across the
existing cap.
PHONE HOLD
The AC-701 can interface Clear-Com with standard telephone systems.
The AC-701 is intended for use on closed/PBX type telephone exchanges.
The user may dial an outgoing call from a telephone extension, switch the
AC-701 to “Phone Hold”, and then hang up the receiver to keep the party
on-line for intercom purposes.
Likewise, an incoming call may be answered by the AC-701 that’s in the “Hold”
condition (instead of lifting the telephone receiver off the hook). When the
phone rings, set the ‘Phone Hold’ switch (on AC-701 front panel) to the “Phone
Hold” position. The AC-701 effectively answers the phone, connecting the caller
to the intercom system. The red LED adjacent to the switch glows to indicate
that the telephone line is seized.
The AC-701 provides a simulated termination to maintain its stability. This
termination is automatically applied when the DC voltage on the TELCO line
input is removed.
For proper operation, the holding coil circuit should be used only on a standard
TELCO line “wet” pair, i.e. a telephone line with a DC voltage across it. For
interfaces with non-TELCO “dry” two wire lines, the holding coil is not needed
and the internal switch on the holding coil module should be set to “bypass”.
Warning: To prevent damage to the Holding Coil Circuitry; when the AC-701 is
used as an interface to TW (RTS type) systems, the internal slide switch
(S1 on the PCB) MUST be set to “BYPASS”.

AC-701 TELEPHONE AND 2-WIRE INTERFACE
1-4

AC-701 TELEPHONE AND 2-WIRE INTERFACE 2-1
TECHNICAL SPECIFICATIONS
AC-701 TELEPHONE AND 2-WIRE INTERFACE TECH-
NICAL SPECIFICATION
dBu is an absolute measurement. 0 dBu is referenced to 0.775 volts RMS
2-Wire Mode
Frequency Response Line - Party Line 100 -3 KHz ± 3dB
Frequency Response Party Line - Line 100 - 14KHz ± 3dB
Output Impedance to Line <=600
Ω
Max output Level to Line >=8dBu
3/4 Wire Mode
Frequency Response Line - Party Line 100 -10 KHz ± 3dB
Frequency Response Party Line - Line 100 - 15KHz ± 3dB
Output Impedance to Line <=600
Ω
Input Impedance 4-Wire Side >=400 Ω
Max output Level to Line >8dBu
Power
Input Voltage Range 20-30 VDC
Rear Panel Connectors
Intercom: (1) XLR-3F
4-Wire (4) Binding post connectors
Front Panel Connectors
Headset: (1) XLR-4M
Front Panel Controls & Indicators
(1) Phone hold switch
(1) Phone hold indicator
(1) 2-Wire/4-Wire mode switch
(2) Line balance switches
(1) Receive level control
(1) Transmit level control
Environmental
32 - 122
o
F (0 - 50
o
C)
Dimensions
19 in. W x 1.75 in. H x 7.5 in. D
(483 mm x 44.5 mm x 190.5 mm)
2

AC-701 TELEPHONE AND 2-WIRE INTERFACE
2-2
Weight
2.53 lbs. (1.15 Kg)
Notice About Specifications
While Clear-Com makes every attempt to maintain the accuracy of the
information contained in its product manuals, that information is subject to
change without notice. Performance specifications included in this manual are
design-center specifications and are included for customer guidance and to
facilitate system installation. Actual operating performance may vary.

WARRANTY i
LIMITED WARRANTY
Vitec Group Communications (VGC) warrants that at the time of purchase, the
equipment supplied complies with any specification in the order confirmation
when used under normal conditions, and is free from defects in workmanship
and materials during the warranty period.
During the warranty period VGC, or any service company authorized by VGC,
will in a commercially reasonable time remedy defects in materials, design, and
workmanship free of charge by repairing, or should VGC in its discretion deem it
necessary, replacing the product in accordance with this limited warranty. In no
event will VGC be responsible for incidental, consequential, or special loss or
damage, however caused.
WARRANTY PERIOD
The product may consist of several parts, each covered by a different warranty
period. The warranty periods are:
• Cables, accessories, components, and consumable items have a limited
warranty of 90 days.
• Headsets, handsets, microphones, and spare parts have a limited warranty of
one year.
• UHF wireless IFB products have a limited warranty of one year.
• UHF wireless intercom systems have a limited warranty of three years.
• All other Clear-Com and Drake brand systems and products, including
beltpacks, have a limited warranty of two years.
The warranty starts at the time of the product’s original purchase. The warranty
start date for contracts which include installation and commissioning will
commence from the earlier of date of the Site Acceptance Test or three months
from purchase.
TECHNICAL SUPPORT
To ensure complete and timely support to its customers, VGC’s User Support
Center is staffed by qualified technical personnel. Telephone and email technical
support is offered worldwide by the User Support Center.
The User Support Center is available to VGC’s customers during the full course
of their warranty period.
Instructions for reaching VGC’s User Support Centers are given below.
Telephone for Europe, Middle East and Africa: [phone] or +44 1223
815000
Return Material
Authorization (RMA)
numbers are required for all
returns.
Both warranty and
non-warranty repairs are
available.

WARRANTY
ii
Telephone for the Americas and Asia: [phone]
Email: [e-mail]
Once the standard warranty period has expired, the User Support Center will
continue to provide telephone support if you have purchased an Extended
Warranty.
For latest contact information please refer to the Service and Support section at
www.clearcom.com.
WARRANTY REPAIRS AND RETURNS
Before returning equipment for repair, contact a User Support Center to obtain a
Return Material Authorization (RMA). VGC representatives will give you
instructions and addresses for returning your equipment. You must ship the
equipment at your expense, and the support center will return the equipment at
VGC’s expense.
For out-of-box failures, use the following contact information:
Europe, Middle East and Africa
Tel: [phone] Email: cust[email protected]
North America, Canada, Mexico, Caribbean & US Military
Tel: [phone] Email: [e-mail]
Asia Pacific & South America
Tel: [phone] Email: [e-mail]
VGC has the right to inspect the equipment and/or installation or relevant
packaging.
For latest contact information please refer to the Service and Support section at
www.clearcom.com.
NON-WARRANTY REPAIRS AND RETURNS
For items not under warranty, you must obtain an RMA by contacting the User
Support Center. VGC representatives will give you instructions and addresses for
returning your equipment.
You must pay all charges to have the equipment shipped to the support center
and returned to you, in addition to the costs of the repair.
EXTENDED WARRANTY
You can purchase an extended warranty at the time of purchase or at any time
during the first two years of ownership of the product. The purchase of an
extended warranty extends to five years the warranty of any product offered with
a standard two-year warranty. The total warranty period will not extend beyond
five years.

WARRANTY iii
Note: VGC does not offer warranty extensions on UHF wireless intercom
systems, or on any product with a 1-year or 90-day warranty.
LIABILITY
THE FOREGOING WARRANTY IS VGC'S SOLE AND EXCLUSIVE
WARRANTY. THE IMPLIED WARRANTY OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE AND ANY OTHER
REQUIRED IMPLIED WARRANTY SHALL EXPIRE AT THE END OF
THE WARRANTY PERIOD. THERE ARE NO OTHER WARRANTIES
(INCLUDING WITHOUT LIMITATION WARRANTIES FOR
CONSUMABLES AND OTHER SUPPLIES) OF ANY NATURE
WHATSOEVER, WHETHER ARISING IN CONTRACT, TORT,
NEGLIGENCE OF ANY DEGREE, STRICT LIABILITY OR OTHERWISE,
WITH RESPECT TO THE PRODUCTS OR ANY PART THEREOF
DELIVERED HEREUNDER, OR FOR ANY DAMAGES AND/OR LOSSES
(INCLUDING LOSS OF USE, REVENUE, AND/OR PROFITS). SOME
STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF
INCIDENTAL OR CONSEQUENTIAL DAMAGES OR THE
LIMITATION ON HOW LONG AN IMPLIED WARRANTY LASTS, SO
THE ABOVE LIMITATIONS MAY NOT APPLY TO YOU. IN ANY
EVENT, TO THE MAXIMUM EXTENT PERMITTED UNDER
APPLICABLE LAW, VGC'S LIABILITY TO CUSTOMER HEREUNDER
SHALL NOT UNDER ANY CIRCUMSTANCES EXCEED THE COST OF
REPAIRING OR REPLACING ANY PART(S) FOUND TO BE
DEFECTIVE WITHIN THE WARRANTY PERIOD AS AFORESAID.
This warranty does not cover any damage to a product resulting from cause other
than part defect and malfunction. The VGC warranty does not cover any defect,
malfunction, or failure caused beyond the control of VGC, including
unreasonable or negligent operation, abuse, accident, failure to follow
instructions in the manual, defective or improperly associated equipment,
attempts at modification and repair not approved by VGC, and shipping
damage. Products with their serial numbers removed or defaced are not covered
by this warranty.
This warranty does not include defects arising from installation (when not
performed by VGC), lightning, power outages and fluctuations, air conditioning
failure, improper integration with non-approved components, defects or failures
of customer furnished components resulting in damage to VGC provided
product.
This limited warranty is not transferable and cannot be enforced by anyone other
than the original consumer purchaser.
This warranty gives you specific legal rights and you may have other rights which
vary from country to country.

WARRANTY
iv