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7
The connections between the Headset Jack and PTT Switch Cables
and the hook-up wire should be soldered and insulated for reliability.
Do not use crimp type splices. They can become intermittent over
time. Use a good quality electrical tape, or better yet, use heat shrink
tubing to cover the soldered connections. The connections to the
headset jacks and PTT switches will also have to be soldered. See
Figure 3 for jack terminal identification.
We also do not recommend using screw type terminal strips for
intercom connections. There have been several instances where
terminal strips introduced high levels of electrical noise like alter-
nator whine into the intercom system. It is acceptable however
to tie the intercom red and green power wires to existing vehicle
terminal strips.
The best place to run the wiring between the unit and the jack and
PTT switches is out of sight. It should be run behind vehicle panels
and/or up in the headliner. This will reduce the chance of personnel
or equipment catching on or damaging the wiring. Wire routing
should take into account normal vehicle operations. Wires should
not interfere with any of the vehicle’s controls, compartments, or
doors. If the vehicle’s cab tilts up for engine servicing, run wiring
along the existing vehicle wiring bundle. Make sure that wiring does
not interfere or restrict the tilting operation. Also, make sure that
the tilting operation will not cut or sever the wiring.
Make sure that the wiring does not rest on sharp edges. Over time
the vehicle’s vibration may cause a sharp edge to cut into the wire.
Use the provided wire grommets wherever the four conductor wire
goes through the hole into a jack box. Use wire ties or tie wraps to
secure and strain relieve the wire.
At this time do not put the covers on the jack boxes or tighten up
the PTT switches. You will need to verify the correct operation of
the system before you close everything up.
Power Connections:
The UltraSound unit will run on 11-16 VDC. CAUTION: UltraSound
units are designed for negative ground vehicles only. They can
be used on positive ground vehicles only if a Sigtronics Positive
Ground Adapter is used. Contact your Sigtronics dealer on pricing
and availability.
Make sure that the vehicle power is turned off before connecting
the UltraSound power wire. The power for the UltraSound unit
comes in on the red and green wires on the Headset Jack and PTT
Switch Cable.
Connect the red wire to vehicle power. (Try not to use a power buss
that also runs electrical motors such as fans or light bars with rotat-
ing lights.) Connect the green wire to the vehicle chassis ground.
INTERCOM WIRING CHECK OUT
System Setup:
Before you connect the vehicle’s radios, check out the system oper-
ation. Do the following without the vehicle’s engine running:
First plug all headsets into the respective headset jacks. Put on one
of the headsets and position the boom mic close to the mouth, as is
the practice with hand-held microphones. Voice clarity is best when
the mic is about ¼ inch away and slightly off center from the lips.
Turn the volume control on the headset, all the way up (clockwise).
On the UltraSound unit, set both the intercom VOLUME control and
SQUELCH control to full clockwise position.
Now turn vehicle power on. Verify that you can now hear yourself
in your headset. Verify also that you can hear all the other headsets
and that they can hear you. If everything is OK, skip to the “PTT
Test” section. Otherwise, if something is not working right, see the
following troubleshooting guide to find and fix the problem before
going on with the installation:
NO INTERCOM IN ANY OF THE HEADSETS:
1. Make sure the UltraSound VOLUME and SQUELCH controls are
set to full clockwise position.
2. Make sure the vehicle power is on.
3. Check the in-line fuse in the UltraSound Headset Jack and PTT
switch Cable.
4. Check the power connection – red wire.
5. Check the ground connection – green wire.
6. Check for a short or open on the headphone wire (Blue wire on
the Headset Jack and PTT Switch Cable). The problem could be
anywhere along the blue wire connection between the headset
jacks and the UltraSound unit.
INTERCOM IN SOME HEADSETS BUT NOT IN OTHERS:
1. Make sure that UltraSound controls are set as above.
2. Make sure that none of the PTT buttons are pressed.
3. Make sure that none of the PTT wires (white/red, white/blue,
white/green or yellow if applicable) are shorted to ground.
4. Check specific “bad” headset jack wiring for:
a) Microphone wire (jack ring terminal) open or shorted to
ground.
b) Headphone wire (jack tip wire) open or shorted to ground.
c) Incorrect wiring - wires switched either at the jack or at the
point where the hookup wire connects to the Headset Jack
and PTT Switch Cable.
LOUD SQUEAL IN THE HEADSETS ALL THE TIME:
1. First make sure all headset plugs are plugged in all the way and
that no part of any headset jack is physically touching any metal.
2. Check headset jack wiring at all jacks. For example, incorrect
wiring such as reversing the jack tip and ring wires will cause a
squeal.
3. Check for open headset jack barrel connection (black wire).
The open could be anywhere along the black wire connection
between the jack and the UltraSound unit.