Sigtronics SCI-6 - Manual (Page 4)

TABLE 1 - P1/J1 - See Wiring Instructions
PIN WIRE COLOR FUNCTION CONNECT TO
1 White/Black Pilot Mic Input Ring Terminal of Pilot Mic Jack
2 White/Red
Pilot Transmit Switch
Input
Pilot Transmit Switch (PTT)
(Switch to Ground to Transmit)
3 Blue *1 Radio Headphone Input Radio Headphone Output
4 Black *2
Intercom Central
Grounding Point “A”
Aircraft Chassis Ground
5 White
Radio Transmit Key
Output
Tip Terminal of Aircraft Hand
Mic Jack, or Key Input of Aircraft
Radio or Audio Panel
6 Brown
Transmit Mic Audio
Output
Ring Terminal of Aircraft Hand
Mic Jack or Mic Input of Aircraft
Radio or Audio Panel
7 Red *3
12 through 28 VDC
Power Input
Intercom Circuit Breaker
8 Tan *4 Passenger #1 Mic Input
Ring Terminal of Passenger #1
Intercom Mic Jack
9 Tan *4 Passenger #2 Mic Input
Ring Terminal of Passenger #2
Intercom Mic Jack
10 White/Blue
Co-Pilot Transmit
Switch Input
Co-Pilot Transmit Switch (PTT)
(Switch to Ground to Transmit)
11 White/Orange Co-Pilot Mic Input
Ring Terminal of Co-Pilot Mic
Jack
12 N/C None No Connection
13 Tan *5 Passenger #3 Mic Input
Ring Terminal of Passenger #3
Intercom Mic Jack
14 Tan *5 Passenger #4 Mic Input
Ring Terminal of Passenger #4
Intercom Mic Jack
15 N/C *5 None No Connection
TABLE 2 - P2/J2 - See Wiring Instructions
PIN WIRE COLOR FUNCTION CONNECT TO
1 Green
Pilot Intercom
Headphone Output
Tip Terminal of Pilot Headphone
Jack
2 Gray
Co-Pilot Intercom
Headphone Output
Tip Terminal of Co-Pilot
Headphone Jack
3 Yellow
Passenger Intercom
Headphone Output
Tip Terminal of Passenger
Headphone Jacks
*1. The blue wire from Pin 3 must be connected to the aircraft radio
headphone output - NOT the speaker output.
*2. Connect all intercom mic jack grounds to a single aircraft
chassis ground point - Point “A” - as shown in Figure 4. (Use
the black washers supplied to insulate the intercom mic jacks
from aircraft chassis ground). Note this intercom central
grounding point is used to eliminate any unwanted electrical
noises, such as alternator whine or strobe noise, from being
induced into the intercom system through the grounds. All
intercom mic jack barrels must be insulated from ground where
they are mounted and connected back to Point “A” on their own
individual ground wire. Similarly, both intercom ground wires
(pin 4) and the push-to-transmit switch grounds must also be
connected back to Point “A”. It is not necessary, however, to
connect the headphone jack barrels to Point “A”. They can
either be grounded where they are mounted or some place
nearby.
*3. The red wire may be connected to either 12V (14V) or 24V
(28V) power source. No switching or adjustments are required
to operate from either source.
*4. Tan wires (pins 8 and 9) are only used on installations that
require extra intercom positions.
*5. Provided on SCI-6 units only.
Skip down to the INSTALLATION CHECK OUT AND ADJUST-
MENTS section on this page.
UPGRADING A SPA INSTALLATION TO A SCI
Chassis Mounting
The SCI-4 is specifically designed to easily replace a SPA-400.
Similarly, the SCI-6 can replace a SPA-600. The panels are exactly
the same dimensions (1” x 2.5”), however the SCI units are 1 3/4”
longer than the SPA units. You will have to make sure that you
have the extra depth required behind your panel. Five mounting
holes are exactly in the same positions. The center hole will have
to be enlarged from 1/4” to 7/16”, the two outer holes will have to
be enlarged to 9/16”, and two additional holes drilled to 3/16” (As
per template).
To upgrade, first remove the SPA unit from the aircraft panel. This
is done by unscrewing the two Phillips head screws and the nut on
the ON/OFF switch. Remove the printed SPA panel. Pull the SPA
unit out and unplug the white connector from the wiring harness.
Next, drill the center hole in the aircraft panel out to 7/16”. Then drill
the two outer holes to 9/16”, then use template to mark the position
of the final two holes and drill. Finally mount the SCI chassis (see
Figure 2 on page 2):
1. Remove the knobs from the Volume and ALL/ISO/CREW
controls using a 0.050” Allen wrench. NOTE: DO NOT REMOVE
the nuts from the Volume/Squelch (VOL/ SQ) or ALL/ISO/CREW
controls.
2. Insert the SCI unit from the rear of the aircraft panel with the
appropriate arrow on the unit chassis pointing upwards. The
squelch indicator lights (LED’s) should easily fit through their
respective holes.
3. Install the printed SCI panel and lightly thread the two 4-40
screws through the holes in intercom panel. The nuts on the
Volume/Squelch and ALL/ISO/CREW controls should fit inside
the aircraft panel holes.
4. Tighten the two screws. Make sure LED’s have unrestricted
movement in aircraft panel holes.
5. Put the knobs on the Volume and Squelch control shafts and
tighten the Allen screws.
Wiring Change
The wiring changes to an existing SPA installation is as follows.
Re-wire the pilot, co-pilot, and passenger(s) headphone lines. You
will not need the 4 foot interface cable (12 or 15 pin) that comes
with the SCI system. You will use the SPA harness already in the
aircraft and the 4 foot headphone/intercom interface cable (3 pin).
In an SPA installation, the tip terminals of the pilot, co-pilot, and
passenger headphone jacks are wired to the blue wire (pin 3).
They need to be disconnected from there and connected to their
respective pins on the headphone/intercom interface harness. (see
Figure 4 on page 3). Make sure that the blue wire (pin 3) is still
connected to the tip of the radio headphone line.
INSTALLATION CHECK-OUT AND ADJUSTMENTS
After the unit is installed, again check that the SCI unit chassis,
jacks, and wiring harness are clear of all aircraft operating controls
and cause no interference with them. Next, to check out the SCI
unit installation plug in all the headset mic and phone plugs into the
respective intercom jacks. Put on the pilot’s headset and position
the boom mic close to the mouth, as is the practice with a hand-
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