Audio Developments AD 245, Manual, Page: 23 / 26

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BBC scale - using the tone generator and millivoltmeter as described above, adjust
mixer levels for a reading of 0dBu, on the millivoltmetez, from a main output.
Select
the meters to L-R and adjust VR1 for a reading of 4. Increase the output signal to
+8dBu and adjust VR2 for a reading of 6.
Decrease the output signal to -8dBu and
adjust VR3 for a reading of 2. Repeat this procedure until an accurate set of readings
is obtained without further adjustment to any of the presets being required.
Now
check all points 1 to 7 on the scale to determine whether they are within specification.
N10 scale - for a meter calibration of TEST = 0dBu. With a main-output signal
of -6dBu, adjust VR1 to give a meter reading at -6. Increase the signal to +6dBu and
adjust VR2 to obtain a meter reading at +6.
Lower the output signal to -18dBu and
adjust VR3 to obtain a meter reading at -18. Repeat this procedure to obtain an
accurate reading at each of these three points. Now check the calibration of all meter
points.
SDR scale - with a main-output signal level of -6dBu, adjust VR1 to obtain a reading
of -12.
Increase the output signal to +6dBu and use VR2 to obtain a reading of 0 on
the meter. Lower the output signal to -18dBu and adjust VR3 to give a reading of -
24. Repeat the procedure to obtain an accurate reading at each of these three points.
Now check the calibration of all meter points.
L-R/MON switch - To enable the meters to read monitor output rather than mono
output when in the MON position a set of links on the main printed circuit card of the
output module have to be broken and another set of links made.
Referring to the diagrams below. Shown is the section of the printed circuit card
containing the link mechanism. Cut links marked ‘X’ and add links in the places
marked ‘Y’. It may be necessary to clear the solder mask from the printed circuit pads
before new links (Y) can be soldered into place.
X (cut) Y(add)