Valcom v-9933a Service Manual

Issue 2

V-9933A

NOISE SENSING VOLUME CONTROL

GENERAL

The V -9933A is designed to electronically adjust the
level of a page by monitoring ambient noise levels in
an area of a building.

SPECIFICATIONS

Purpose

The V -9933A provides automatic paging level
adjustments in areas where ambient noise levels are
continuously changing.

Application

• Valcom one-way paging systems

Features

• Solid-state design

• Low power requirements

• Self-contained or optional remote sensing device

Capacity

Each V -9933A will control the audio for up to 150
Valcom one-way amplified speaker assemblies in a
single zone. Multiple V -9933A units can be used
within the same zone.

Additional Materials Required

At the time of installation, the installer should provide
the following materials:

• 24VDC power supply (If existing supply is

inadequate)

• Optional V -9934, Remote Sensing Device (Up to 4

units)

Dimensions/Weight

The V -9933A is designed to be wall mounted.

• 7.30" H x 4.50" W x 2.00" D
(18.54cm H x 11.43cm W x 5.08cm D)

• 0.9 lbs. (.41kg)

Power Requirements

Power Requirement: -24VDC Filtered Battery
Operating Current: 150mA

Nominal Specifications

1 947933

Automatic Level Adjustment Range: See Chart 1
Power Output: -10dBm
Frequency Response: 50-12kHz +3dB
Input Impedance: 25k Ohms
Output Impedance: 8 Ohms
Operating Temperature: 0 to +50 degrees C
Power Requirements: -24VDC signal battery
Monitor Reset: 5 seconds

OPERATION

The V -9933A, Noise Sensing Volume Control,
continuously monitors the surrounding area noise by
utilizing a built-in or optional remote microphone.
When a page is made, the V -9933A electronically locks
onto the last area noise sample. A -23dBm signal or
higher is required on the input before the
V -9933A will activate and lock.

Once activated, the amplifier is automatically set to the
proper gain level for the amount of background noise.
The amplifier will remain locked at that gain level for
the duration of the page.

After the page is made, there is a five (5) second delay
before the V -9933A starts monitoring the area noise
levels. Refer to Figure 3 for a simplified schematic of
the V -9933A.

INSTALLATION

These instructions cover only the installation
procedure of the Valcom V -9933A. Please consult

applicable instructions for control equipment or any
other equipment used.

Precautions

All precautions have been taken at the factory to
insure that the equipment functions properly. Please
observe the following precautions or the equipment
may be damaged and the warranty voided.
a. Unplug the power supply before connecting any

wires or cables to the control units connecting
block. With power ON, accidental bridging of two
terminals with a wiring tool may damage electronic
circuits.

b. Do not use a lamp tester to check signals. Use a

voltmeter. A lamp tester, when first applied is a
short circuit to electronic circuits.

c. Do not apply power to the control unit until all

connections have been double-checked.

NOTE: The V-9933A cannot be used to control
music or on an audio zone with background
music.

Mounting

a. Select mounting location central to the noise

producing equipment.

b. Carefully unpack the unit from the carton and

inspect.

c. Unsnap cover from base and mount base to wall

using pan head screws.

Connections

Refer to Figure 2 while performing the following:
a. Connect the page control uni t speaker output to T

and R input of V -9933A.

b. Connect the input of amplified speaker to T and R

output of V -9933A.

c. Connect power supply -24VDC(-) and GND(+) to

-24VDC and GND terminals on V -9933A.

d. Connect optional remote microphone (V -9934) to

“Ext Mic In” terminals.

Set-Up and Adjustment

a. Complete all connections to page control unit, V -

9933A, one-way amplified speakers and power
supply. Do not activate power supply until step c.

b. 1) Set the sensitivity adjustment fully clockwise

for minimum ambient noise environment.

2) Turn dip switch 1 ON (Setup) and set dip
switches 2 and 3 to the desired range; typical
range would be 2 OFF, 3 ON=30dB (See
Chart 1).

TABLE 1 - TROUBLESHOOTING CHART

3) Set switch 4 to appropriate use.
c. Apply power to the V -9933A. LEDs 8, 4, 2 and 1

should briefly light in sequence and then go off. If
any LEDs remain lit, then a failure is indicated;
repeating setup steps is recommended.

d. With the ambient noise at a minimum and no

active program on the input, turn the sensitivity
adjustment counter -clockwise until LED 1
illuminates. Make a test page and adjust the page
volume controls to a suitable volume. If
necessary, the sensitivity adjustment may be
increased. However, it is not desirable for all 4

LEDs to be lit during normal operation.
e. Return dip switch 1 to the OFF position.
f. Installation and set-up now complete.

NOTE: After adjusting “sensitivity adjust”
(microphone gain), wait 20 seconds before
executing a test page (See Troubleshooting
Chart, Table 1).

TECHNICAL ASSISTANCE

When trouble is reported, verify that power is being
supplied to the unit and there are no broken
connections. Check voltages for proper polarity on
terminals.

Table 1 identifies symptoms of some possible problems
with solutions. If a spare unit is available, continue to
troubleshoot by substituting the spare unit for the
suspected defective unit.

Assistance in troubleshooting is available from the
factory. When calling, you should have a VOM and a
telephone test set available and be calling from the job
site. Call [phone] and ask for Technical Support,
or call [phone] for Valcom 24-hour Faxback
System or visit our website at http://www.valcom.com.

The V -9933A is not field repairable. Valcom equipment
contains no user serviceable parts inside. Valcom,
Inc. maintains service facilities in Roanoke, VA.
Should repairs be necessary, attach a tag to the unit
clearly stating your company name, address, phone
number, contact person and the nature of the problem.
Send the unit to:

Valcom, Inc.

Repair and Return Dept.

5614 Hollins Road

Roanoke, VA 24019-5056

SYMPTOMS POSSIBLE SOLUTIONS

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