wheelock AA-20-40 Schematic
273 Branchport Avenue
Long Branch, N.J. 07740 Thank you for using our products.
(800) 631-2148
www.wheelockinc.com
AUDIOLINK SERIES
INSTALLATION INSTRUCTIONS
MODELS AA-20/AA-40 PAGING AND COMMERCIAL PA AMPLIFIERS
Use this product according to this instruction manual. Please keep this instruction manual for future reference.
GENERAL APPLICATION INFORMATION:
Wheelock's AudioLink Series Model AA-20 and AA-40 Amplifier are output rated at 20 watts RMS and 40 watts RMS respectively.
These amplifiers afford a choice of four different inputs: two low impedance microphone inputs, one telephone paging input, and one
high impedance auxiliary input. Three input channels allow these inputs to be used actively at one time: one microphone input, a
choice of a telephone paging input or a second microphone input, and an auxiliary input. Note that the auxiliary input (i.e.,
background music, tone generator, etc) may be automatically soft muted whenever a telephone page is generated or a microphone is
used. After completion of the page, the music will rapidly return to its original level. This function is switch selectable.
A built-in limiter circuit compensates for the varying voice levels and paging styles of the people who have access to telephone
paging or a microphone. The limiter maintains rated output without distortion. This function is switch selectable.
The amplifiers feature tamper-resistant individual input volume controls, as well as a master volume control, individual treble and
bass controls, a low-cut horn protect switch, one input selector switch, a power on indicator, a limiter ON-OFF switch, a music mute
ON-OFF switch, a peak level indicator, and a line output jack.
Both models operate from 115 volts, 60Hz as well as 230 volts, 50Hz, switch selectable, and have a power consumption of 65 watts
(AA-20) and 115 watts (AA-40). The units have a thermal breaker in the power transformer as well as a thermal cut-off and current
limiting for overload protection on the output. The thermal breaker in the transformer is automatically resettable.
NOTE: All CAUTIONS and WARNINGS are identified by the symbol
. All warnings are printed in bold capital letters.
CAUTION: In the event the transformer's thermal breaker does not reset, have the trouble investigated by an authorized service
technician or return unit to the factory.
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS UNIT TO RAIN
OR MOISTURE.
UNPACKING:
The amplifier was carefully checked before leaving the factory. Inspect shipping container and unit carefully for indication of
improper handling. If the unit has been damaged, make an immediate claim to the carrier.
MOUNTING INSTRUCTIONS:
The amplifiers are designed for either shelf or wall mounting. For surface wall mounting, use the 2 keyhole slots in the chassis cover.
Be sure to use hardware suitable for the mounting surface. Do not block air flow to top, front, back or bottom. Blocking the air flow
will cause automatic thermal shutdown.
CAUTION: These devices are not intended for use in hazardous locations as defined by the National Electrical Code (NEC) and
by the National Fire Protection Association (NFPA).
WARNING: DO NOT USE THIS UNIT IN LIFE-SAFETY APPLICATIONS. THIS UNIT IS UL 813 LISTED AND
CUL LISTED FOR COMMERCIAL AUDIO ONLY.
POWER AND GROUNDING:
The 115 VAC line cord has a three-prong plug which should be plugged into a three wire grounded electric outlet. It is very
important to maintain the amplifier ground for safe and trouble-free operation. If there is no grounded electric outlet, use a 2 prong to
3 prong plug adapter, with grounding lead, and connect the grounding lead to a metallic bond on the outlet; (i.e. the screw which
secures the outlet's wall plate).
VOLTAGE SELECTION:
Factory set @ 115VAC for U.S. market; units for export are set @ 230VAC. Make absolutely certain that the voltage selection
switch, located on the side of the amplifier, is set for the intended line voltage (i.e., 115VAC or 230VAC). Improper voltage selection
can result in permanent damage to, or failure of, the unit.
Copyright 1995, 1998, 1999 Wheelock, Inc. All rights reserved.
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TECHNICAL SPECIFICATIONS:
# PARAMETERS AA-20 AA-40 TOLERANCE COMMENTS
1 Power Output
@ 1KHz
2 Total Harmonic
Distortion
20 Watts RMS 40 Watts RMS ±1dB 115VAC 60Hz ±5%
230VAC 50Hz ±5%
Less than 1% THD
+1%
Same as above
@ Rated Output
3 Outputs 8 OHMS, 25V, 70.7V, 100V ±1.5dB Bal. or Unbal.
4 Line Output 1.1V ±20% RL = 150 OHMS
INPUTS TELEPHONE MIC 1/MIC 2 AUX ------ ------
5 Impedance 600 OHMS 600 OHMS 12K OHMS ------ @ 1kHz
6 Sensitivity
-20dBM
(77.5mV -
-16 +20)
1mV
220mV
TEL ±2dB
MIC ±.5mV
AUX ±20%, -50%
To Produce
Rated Output
7 Frequency Response 300Hz-5kHz 50Hz-15kHz 50Hz-15kHz ±3dB Ref. 1kHz @ 1W
25kHz MAX.
8 Signal to Noise Ratio 65dB 60dB 70dB -4dB +10dB Not Weighted
9 Type of Input
10 Controls TEL/MIC 1, MIC 2, AUX, BASS, TREBLE, MASTER VOLUME,
Transformer
Isolated/Bal.
Balanced or
Unbalanced
Unbalanced
------
TEL/MIC 1 SW., LIMITER ON/OFF SW., AUX MUTE ON/OFF SW.
------
Front Panel
Mount
LO CUT SWITCH Front Panel
Mount
11 Indicators Green LED - Power ON Red LED - Peak Level Front Panel
Mount
12 Protection Transformer thermal circuit breaker, no-load, low-load, short circuit and
thermal overload protection on output and supply regulators.
------
# PARAMETERS AA-20 AA-40 TOLERANCE COMMENTS
13a Treble Control -10.5dB TO +10.5dB @ 12kHz ±4dB -----13b Bass Control +10.5dB TO -10.5dB @ 100Hz ±4dB -----14 Lo-Cut Switch -6dB @ 250Hz +1dB, -2dB -----15 Automatic Limiter
For Paging
±4dB output level maintained without clipping,
even while exceeding rated input level up to
------
Paging Inputs
20dB.
16 Automatic Mute
Operation
Output level 1 watt for 40dB muting Min. Mute of music output
while page is activated
17 Regulation No load to full load output less than 2dB ------ Stability of amp. with
or without load
18 RFI Protection RFI test: use CB transmitter output in same room
- minimum 20ft. from amplifier.
19 Consumption @
65 Watts 115 Watts ±5% @ 115VAC, 60Hz,
FRO
------
No Pickup
±5%
INPUT CONNECTIONS: (Figures 1 & 2)
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Sheet 2 of 9
CAUTION: Disconnect power prior to connecting or disconnecting to either the inputs or the outputs. Failure to disconnect
power when connecting or disconnecting inputs or outputs could cause internal damage.
Telephone Paging Input (Figure 1)
: Connect telephone wires to the input screw terminals marked TIP and RING. Set TEL/MIC 1
Switch (on front panel) to TEL position. For Tip and Ring connections to various types of telephone paging access, see Figures 7A,
B & C. NOTE: This input is a transformer isolated, line level input and may be used for applications other than telephone paging
(i.e. tone signaling).
Microphone Inputs (Figure 1)
: Connect balanced low-impedance microphone wires to the input screw terminals marked LO-Z. The
shield must be connected to the GND screw terminals. An unbalanced microphone may be connected to the same screw terminals.
However, one of the two LO-Z terminals for that input must be connected to the adjacent screw terminal marked GND. Install a
jumper wire, between one LO-Z screw terminal and the GND screw terminal.
NOTE: To avoid noise pick-up, the microphone input cable should be a shielded cable, with the shield connected to the input GND
terminal.
MIC 2 is a low impedance (LO-Z) microphone input channel. TEL/MIC 1 is a switch selectable telephone paging, or low impedance
(LO-Z) microphone input channel.
Input Connections
Figure 1.
Auxiliary Input (Figure 2)
:
To connect an FM tuner, CD player, tape player, tone generator, or any other line level program source (i.e., mic/line mixer) to the
AUX input jack on the side panel, use a single conductor shielded cable terminated in a standard RCA type phono plug.
AUX input is a high impedance (HI-Z) input channel.
Aux High Impedance (Hi-Z) Input
OUTPUT CONNECTIONS:
(Figures 3 & 4)
Referring To Figure 3
:
Figure 2:
(AA-40 Shown - AA-20 Similar)
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