Toa W-912A Service Manual - Manual (Page 13)

13
9. OPERATION
Be sure to complete all connections before operation.
9.1. Basic Operation Procedure
Step 1. Press the power switch to turn on the power.
The power indicator lights. The amplifier comes into operation about 5 seconds after the power has
been switched on.
Step 2. Adjust the individual input and master volume controls for the optimum level.
Turn the knob clockwise to increase the output level and counterclockwise to decrease it. Sound
quality is downgraded when the Peak Indicator remains lit.
Step 3. Adjust the graphic equalizer.
The one-octave graphic equalizer allows more precise frequency adjustments response to room
acoustics, reducing feedback opportunities and improving intelligibility.
Characteristic of this equalizer is on p.14. Adjust it to obtain the desired frequency response by
actually hearing the sound or by using pink noise.
To make the adjustment, place the EQ switch in the IN position.
If a control knob is moved up, center frequency is boosted and if down, it is cut. Placing the EQ switch
in the OUT position bypasses the equalizer circuit and makes frequency response flat.
9.2. Filter ON/OFF
When the HIGH PASS FILTER switch is in the ON position, low frequency is cut. In this event, low frequency
below 180 Hz may be cut at a 12 dB/OCTAVE rate. When LOW PASS FILTER switch is in the ON position,
high frequency of 7 kHz or higher may be cut at a 12 dB/OCTAVE rate.
To bypass the filter, place the filter switch in the OFF position.
9.3. Compressor ON/OFF
If the COMPRESSOR CONTROL switch is set to
OFF, it bypasses the compressor circuit. Turn it
clockwise to activate the compressor and to
adjust the limiting level. Since turning it fully
clockwise limits the output level to the maximum,
be sure to turn it to the appropriate position so
that the Peak indicator does not light.
9.4. Adjusting release time
Compressor release time is factory-preset at 2
seconds. Adjust the release time with the
Release time control as needed. Turn the control
to the MAX position to increase the release time,
and to the MIN position to decrease it.
9.5. Replacing Fuse
Each amplifier has an output fuse to protect the amplifier from short-circuiting at the output or overloading.
Check the fuse when speakers connected do not sound. If the fuse blew, replace with the same type fuse
after confirming the following points.
• Speaker cables are not short-circuited or the load does not exceed the rating specified.
• Wiring is correctly done at the output terminal board.
Output
Input
Clip
OFF
HALF
MAX
COMPRESSOR
CONTROL
Rated
1/2
MIN MAX
Release time control
VR303
VR302
CN302
VR301
Equalizer printed
circuit board