Dolby Laboratories 430 - Manual (Page 13)

3-2
Similarly there is a slot in the back of each two-channel frame and the other connectors should be mated,
(bump upwards) with these observing the warning about excessive force. The channel frames can be
stacked with the control unit at the top or bottom.
Next, the 15 meter shielded cable should be located and plugged into the 15-way D connector on the back
of the control unit. The other end of this cable connects directly to the rear of an optional Cat. No. 428
three-channel remote housing or to the flat cable which links three freestanding remote control units for
console mounting.
Next, the audio in/out connections should be made. The connectors for this are standard XLR type 3-pin
audio connectors. Connect audio cables to the inputs and outputs using two-conductor shielded cable.
Connect shields at one end only to avoid ground loop problems.
The XLR connectors are wired with pin 1 as ground and pins 2 and 3 as an electronically balanced pair.
Phase continuity is preserved with the same pin numbers used for input and output. In an installation where
the source and/or load are unbalanced, avoid ground loops by using two-conductor shielded cable exactly
as for balanced circuits and ensure that the unbalancing (connecting one of the two balanced signals to
ground) occurs only at the end remote from the Model 430. Both audio signals must be connected; neither
may be left open. In the interests of maintaining international standardization, we suggest that you follow
the IEC convention: XLR pin 2 signal is “high/hot” and pin 3 signal is “low/cold.”
GROUNDING–To ensure conductivity between all the cases of the modules making up the system,
the green/yellow jumper links should be attached to the lugs provided in the middle of the back of
each module in a daisy chain fashion. This should be done even in rack mounted installations since
paint and anodizing can prevent a low impedance path from existing between the modules.
It is normal practice to connect program (audio) ground to power line ground for many reasons,
including safety. On occasion (particularly with long signal lines or incorrect wiring of the cable
shields) induced hum can sometimes be reduced by separating the two grounds. A link behind the
front panel of the control unit provides this feature. There is always a 1 k ohm resistor across the
link so that the audio ground is never totally isolated from the chassis ground.
Verify that all connectors are securely mated and read the safety information on page 3-5. When you are
confident that you have observed its provisions, connect the power cable between the control unit and a
power outlet.
Power up the unit. The LEDs on the front of the control unit should indicate that channels 1 to 3 are present
and that there are no errors. Errors are channels which have no remote addressed to them or remotes with
no channels to control. As shipped, the frame with a pair of modules installed will have the addresses set to
channels 1 & 2 and the frame with a single module will have its module address set to channel 3. (If errors
are found at this stage, see Channel Number Assignment in Section 3.3.)
The unit powers up with processing off. To verify which remote unit controls which channel, the button on
the bottom of the remote unit should be pressed to see which channel responds by changing the state of its
front panel LEDs. An audio signal should be applied to each channel in turn and the effect of moving the
various controls verified.
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