Signet PDA500, Руководство по эксплуатации и инструкция

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Page 3
Doc No. DCP0000518 JH 12/7/99 rev2
Read this manual throughally before start-
ing installation, the following procedure should
be used.
1. Install the loop (see page 6)
2. Before connecting a loop to the amplifier use a
multimeter to check the loop is not shorted to
ground at any point, (it will almost certainly
damage the amplifier if it is).
3. Connect music or speech input signal to the
amplifier. The peak line level of this signal
should be approximately 1V.
4. Ensure input levels controls and drive control
are fully anti-clockwise. .
5. Increase the input level controls until the ‘limit’
LED is just flashing. This indicates that the
dynamic range processor is receiving a signal
of the correct level. If you are using both inputs
the level controls act as a simple mixer.
6. Adjust the drive control until the required cur-
rent peak is produced. (see page 5). Care
should be taken when doing this to ensure
the current is within the recommended
rating of the cable. The average current
output should be approximately one quar-
ter of the maximum peak.
7. Using an induction loop receiver (eg SigNET
Rxti2), listen to the signal inside the loop. It is
also advisable to check the system with a field
strength meter. Please note that the orientation
of the field strength meter may influence the
reading.
Mains Hum
Background hum can sometimes be heard
when testing an installation especailly when test-
ing with a induction loop reciever. This is not
caused by the loop system and will NOT nor-
mally be heard by hearing aid users, due to built
in filtering in most hearing aids.
The source of the hum is most likely to be
mains wiring, particularly in old buildings where
Live and Neutral cables may take different
routes, thus creating an induction loop radiating
at 50Hz.
If the client complains of mains hum simply
disconnect the loop to prove that the source is
unrelated.
Installation Input connections
Two input connectors are standard 3pin
XLR. One input is for line level the other for mic.
level signals. For pin connections use the follow-
ing chart or see the back of the unit which has
the pin outs marked next to the relavent connec-
tor.
LIne Input
Microphone input
Unbalanced Balanced
pin1 ground pin1 ground
pin2 signal pin2 Hot
pin3 link to pin1 pin3 Cold
Unbalanced Balanced
pin1 ground pin1 ground
pin2 signal pin2 Hot
pin3 link to pin1 pin3 Cold
Phantom is supplied on pins 2 and 3,
44V, 5mA maximum per pin.