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• Do not block the ventilation slots in the unit's cover.

Doing so may cause heat to build up inside the unit
and result in fire.

• Avoid installing the unit in humid or dusty locations,

in locations exposed to the direct sunlight, near the
heaters, or in locations generating sooty smoke or
steam as doing otherwise may result in fire or
electric shock. 

When the Unit is in Use 

• Do not place heavy objects on the unit as this may

cause it to fall or break which may result in
personal injury and/or property damage. In
addition, the object itself may fall off and cause
injury and/or damage.

• Make sure that the volume control is set to

minimum position before power is switched on.
Loud noise produced at high volume when power is
switched on can impair hearing. 

• Do not operate the unit for an extended period of

time with the sound distorting. This is an indication
of a malfunction, which in turn can cause heat to
generate and result in a fire.

• Contact your TOA dealer as to the cleaning. If dust

is allowed to accumulate in the unit over a long
period of time, a fire or damage to the unit may
result. 

• If dust accumulates on the power supply plug or in

the wall AC outlet, a fire may result. Clean it
periodically. In addition, insert the plug in the wall
outlet securely.

• Switch off the power, and unplug the power supply

plug from the AC outlet for safety purposes when
cleaning or leaving the unit unused for 10 days or
more. Doing otherwise may cause a fire or electric
shock. 

2. GENERAL DESCRIPTION 

Equipped with Priority function, Chime function, and 2 Zone selector switches, TOA's A-1803, A-1806, and A-
1812 PA Amplifiers are designed to suit PA system applications such as paging announcements,
intercommunications, BGM and broadcasting in schools, offices and shops.

3. FEATURES 

• Power output of 30 W (A-1803), 60 W (A-1806), and 120 W (A-1812).

• Built-in chime unit (1-tone chime, 2-tone chime, and ascending 4-tone chime)

• Chime can be sounded on use of the MIC 1 input (an optional PM-660D Paging Microphone connectable) or

on Telephone paging.

• Priority function provided for inputs as follows:

Emergency input has the highest priority to all inputs. (Contact activation)
Telephone Paging input has precedence over the inputs other than Emergency input.
MIC 1 input has precedence over the inputs other than Emergency and Telephone Paging inputs.

• Emergency function performs as follows:

Closing the contact at the Emergency Control input terminals turns ON the unit's power even if it is OFF, and
both Zone selector switches.

• Following audio signal inputs suitable for the intended applications: 3 Microphone inputs, 3 AUX inputs, 1

Emergency input, and 1 Telephone Paging input.

• Phantom-powered Microphone inputs (power ON/OFF switchable).

• Combined XLR/phone jack Microphone inputs for convenient use.

• Electronically-balanced Microphone inputs.

• Speaker selectors for 2-zone broadcast.

• Tone controls (bass and treble).

• Output level meter.

• Master volume control for overall input (excluding the Emergency input) signal level adjustment.

• AC and DC power source.

An all-pole mains switch with a contact separation of at least 3 mm in each pole shall be incorporated in
the electrical installation of the building. 

Summary of Contents for A-1803

Page 1: ...G INSTRUCTIONS PA AMPLIFIER A 1803 A 1806 A 1812 Please follow the instructions in this manual to obtain the optimum results from this unit We also recommend that you keep this manual handy for future reference ...

Page 2: ... Telephone Paging Input voice activated priority 10 8 2 Microphone Input voice activated priority 10 8 3 Paging Microphone Input 10 8 4 Emergency Control Input 10 8 5 Telephone Paging Control Input 10 9 SPEAKER ZONE SELECTION 11 10 INSTALLATION 11 11 RACK MOUNTING 11 12 CONTROL SETTINGS 12 13 DIMENSIONAL DIAGRAM 12 14 INTERNAL MODIFICATIONS 14 1 Turning On Off LINE OUT 1 2 in conjunction with ZONE...

Page 3: ...al to avoid electric shock Never ground to a gas pipe as a catastrophic disaster may result Avoid installing or mounting the unit in unstable locations such as on a rickety table or a slanted surface Doing so may result in the unit falling down causing personal injury and or property damage When the Unit is in Use Should the following irregularity be found during use immediately switch off the pow...

Page 4: ...SCRIPTION Equipped with Priority function Chime function and 2 Zone selector switches TOA s A 1803 A 1806 and A 1812 PA Amplifiers are designed to suit PA system applications such as paging announcements intercommunications BGM and broadcasting in schools offices and shops 3 FEATURES Power output of 30 W A 1803 60 W A 1806 and 120 W A 1812 Built in chime unit 1 tone chime 2 tone chime and ascendin...

Page 5: ...reble control Adjusts treble response Rotate clockwise to increase treble output and counterclockwise to reduce it The center position provides flat characteristics 7 Zone indicators Light to indicate the broadcast zone zone1 2 selected with the Zone selector switches Both Zone selector switches 8 are turned on their indicators are lit even if off while the EMERGENCY or TEL control input terminals...

Page 6: ...600 Ω unbalanced Connect to the line input of other equipment Continuously outputs signals irrespective of the zone selector switch settings Factory preset Internal modification can change this operation as follows Turning on off the LINE OUT 1 and 2 can be interlocked with the Zone 1 and 2 selector switches respectively For this modification p 13 for details please consult your TOA dealer 24 AUX ...

Page 7: ...V terminals cannot be used at the same time Impedances indicated in the figures represent the total speaker system load impedances 24 V C C 4 16Ω DIRECT 100 V INPUT ZONE 2 100 V ZONE 1 100 V 24 V WARNING 5 2 Remote Power ON OFF Control Connection The optional P 1812 PA Amplifier s power can be remotely switched ON or OFF with the power switch operation of the A 1800 series This remote control oper...

Page 8: ...ENCY P 1812 Connect this cable when requiring remote power ON OFF control While the Emergency control input terminals remain shorted the power of all the connected A 1800 series and P 1812s is turned on and the A 1800 s ZONE 1 and 2 speaker outputs are enabled allowing only Emergency input signals to go through bypassing the master volume control Opening the control input terminals automatically r...

Page 9: ...Chime Selection Table below 6 FUNCTION SWITCH SETTINGS Set the rear mounted Function switch as shown below 1 2 ON 3 4 5 6 7 8 Switch No 2 3 OFF OFF ON OFF OFF ON ON ON Chime Tone 4 Tone Chime 2 Tone Chime 1 Tone Chime OFF Chime Selection Table 7 CHIME FUNCTION 7 1 MIC 1 Chime Tone When using the MIC 1 s DIN plug shorting its Pins 4 and 5 allows the chime of type selected with the Function switch s...

Page 10: ...to the original level 8 4 Emergency Control Input Shorting the Emergency Control input terminals turns on the power even if off and enables both ZONE 1 and 2 speaker outputs muting all input signals other than the Emergency input signals which go through bypassing the master volume control Opening the control input terminals automatically returns the muted signals to the original level Internal mo...

Page 11: ...ff allowing the Emergency or Telephone Paging input signals to be broadcast from both ZONE 1 and 2 speaker outputs Opening the control input terminals automatically returns the operation to the original status 10 INSTALLATION Keep the unit s all sides over 10 cm away from objects that may obstruct air flow to prevent the unit s internal temperature rise 11 RACK MOUNTING To mount the unit in a stan...

Page 12: ... corresponding volume control so that the red indicator doesn t light Note that the sound quality is downgraded when the red indicator remains lit To prevent the accidental change of the settings of input volume and tone Bass and Treble controls remove their knobs after setting them to the desired position and attach the optional YA 920 Volume Control Covers instead MIC 1 BASS MIC 2 Control knob Y...

Page 13: ...ch the transformer case to be installed in the next step Step 2 Install and solder the optional IT 453A Input Transformer in place of T400 indication on the Control circuit board 14 2 Turning the Power Off to Disable Broadcast with EMRGENCY Control Activation Install the SJP102 jumper to OFF position 14 1 Turning On Off LINE OUT 1 2 in conjunction with ZONE 1 2 Selector Switch To interlock LINE OU...

Page 14: ... for chime circuit ZONE 2 ZONE 1 ZONE 1 100 V ZONE 2 100 V Zone 2 Zone 1 POWER TEL EMERGENCY 220 230 V AC or 240 V AC 50 60 Hz PT Fuse Fuse Output level meter JP OT DIRECT 100 V 4 16 Ω 24 V INPUT C C REC OUT 0 dB 600 Ω LINE OUT 0 dB 600 Ω 0 dB 1 2 ON OFF ON OFF 20 dB 20 dB 20 dB 20 dB 0 dB 0 dB 0 dB BASS TREBLE MASTER volume Interlocked with Relay 1 ZONE 1 Relay 1 Relay 2 Interlocked with Relay 2 ...

Page 15: ...ed RCA pin jack LINE 1 2 4 0 dB 2 600 Ω unbalanced RCA pin jack MOH 0 dB 2 600 Ω transformer balanced M3 screw terminal 1 SPEAKER SELECTOR 2 zone high impedance 5 100 V line individual selector switch M4 screw terminal 1 DIRECT SPEAKER OUT High impedance 5 100 V line M4 screw terminal 1 Low impedance 4 16 Ω M4 screw terminal 1 Note Both Low and High impedance terminals cannot be used at the same t...

Page 16: ... to change without notice for improvement Accessories AC power cord 1 Terminal cover 1 Terminal cover mounting screw M4 x 8 2 Optional products Rack mounting bracket MB 25B Volume control cover YA 920 Input transformer IT 453A Available as a service part whose part code is 114 03 118 30 Model No A 1803 A 1806 A 1812 Priority EMERGENCY Overrides other inputs TEL Overrides other inputs except EMERGE...

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