Model 737 Soundtrack Loudness Meter - Leq(m) Operation and Features
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2.4 Mains Power
The Model 737 uses a mains transformer that converts incoming AC to 24 VAC. The
transformer has 1 meter leads and should be placed at the base of the equipment rack in
which the unit is mounted. The tr ansformer should not be operated with the 24 V leads
shorted. Transformer units are available for 200–240 VAC input and 100–125 VAC input.
Please ensure that the correct transformer is ordered for your local mains voltage.
•For 110 VAC, Dolby part number is 54058
•For 230 VAC, Dolby part number is 54057
In some countries, the primary cable for the module may not have a mains plug fitted.
These unterminated leads must be properly wired to a mains plug in accordance
with the following international code:
•Brown wire: Live or hot
•Blue wire: Neutral
CAUTION: If you are uncertain about the wiring of your mains outlet do not use it.
Consult a qualified electrician.
2.5 Interface
The connections for remote start/stop control are normally wired to a relay across the
projector motor or to a console-mounted toggle switch. When the contacts close or the
Stop button is pressed, the display flashes the last measured value. When the contacts
open again, or the Start button is pressed, the unit enters measurement mode. Pressing
the Cal button causes the unit to enter calibration mode, regardless of the last function
pressed. To remotely start a measurement from calibration mode, the contacts must
close and then open again. The contacts should be capable of passing 10 mA and should
not have contact with other circuits. A simple toggle switch or a pair of uncommitted
relay contacts is ideal.

2.5.1 Grounding

There is no connection between the audio common inside the unit and the metalwork.
For most grounding schemes, a link of 16 AWG between pins 4 and 7 of the power/
control connector provides a satisfactory grounding scheme. If this induces hum be-
cause of a loop via the rack mounting, the link can be removed.
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