PS Engineering PMA7000B Installation Manual - Manual (Page 13)

PS Engineering
PMA7000B Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-780-0005 Page 2-6 Rev. 10, December 2012
2.4.11 Unswitched inputs
J1, pins T, 17, U and X are unswitched, unmuted inputs. These inputs are presented to the pilot and copi-
lot regardless of the audio configuration, and will always mute the entertainment inputs. These 510 Ω
inputs can be used for altimeter DH audio, GPS waypoint audio, autopilot disconnect tones, or any other
critical audio signal. J1Pin T is provided to the pilot’s headset even when the unit is off, or in fail-safe
mode.
If the KMA 24 installation includes “External Speaker” or “Internal Speaker” connections to J1 Pins X
and U respectively), these will have to be disconnected to avoid interference with the Unswitched inputs
#3 and #4.
NOTE: Inputs 1, 2 and 4 are fixed (1:1), and any audio level adjustments must be made at the input
source. Input 3 (Bottom Connector pin U) has adjustable attenuation.
2.4.12 PA Mute (J1, Pin 18)
Pin 18 of J1 is a TTL logic output that is pulled low during PTT operation. This serves as an input to ex-
ternal public address system to prevent feedback during transmissions.
2.4.13 Public Address Function (J2, Pin 18)
By connecting the top connector (J2), Pin 18 to ground, the pilot’s microphone audio is placed on the
cabin speaker output. When the pilot’s PTT is activated, his voice is heard over the speaker. The copilot
can continue to use the selected com.
We recommend installing a toggle switch to connect the cabin speaker output (pin W, bottom connector)
to a rear or public address speaker instead of the cockpit speaker close to the pilot. This will prevent feed-
back.
2.4.14 Control Output (J2, Pin A)
Pin A of the top connector is pulled to ground whenever the AUX button is depressed. This serves as a
control line for external devices, such as a entertainment system that the pilot wishes to control.
This could be used in conjunction with a PA to control J2, Pin 18, as well as an external relay to change to
the cabin speaker from the cockpit.
This pin can also be used to control passenger Karaoke Mode, by connecting to pin V of the J2.
2.4.15 Intercom wiring
The top connector (J2) is for the intercom and additional functions. See Appendix for intercom connection
configurations. It is critical to the proper operation of this system to have this connector wiring made in
accordance with these diagrams. Use 2- and 3-conductor, MIL-spec cable as shown. Connect the shields at
the audio panel end only, and tie to the audio low inputs as shown.
NOTE: The top connector harness can be custom made by PS Engineering, Inc. Simply call the factory
and obtain a wire harness work-sheet. The harness will be made to your specifications and fully function-
ally tested. All hardware is included.
2.4.15.1 Alternate Intercom Mode (Bottom connector Pin 14)
(Units with serial number beginning with (“J” or above)
If an external switch is installed between pin 14 of the bottom connector and ground, the PMA7000B can
be placed into “Alternate Intercom Mode.” In this mode, when the ICS is in “ALL” mode, the passengers
will not hear aircraft radio. In addition, the passengers’ microphones are not heard by the crew when the
radios are active.