PS Engineering PMA7000M-S Installation Manual - Manual (Page 12)

PS Engineering
PMA7000M-S Series Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-070-0012 Page 2-5 Rev. 12, Sept. 2000
2.4.10 Backlighting
The PMA7000M-S has an automatic dimming of the pushbutton annunciator LEDs and marker lamps con-
trolled by a photocell. Control of the unit backlighting is through the aircraft avionics dimmer. Connect the
dimmer control line to J1 pin D for 14 volt systems, and to J1 pin F for 28 volt systems. Pin E is light
ground.
If an external dimmer control is not used, a constant low level back light illumination can be established for
nighttime viewing. Pin D or F (depending on system voltage) must be tied to power (J1, pin 20) for the back
lighting system to work. The photocell mounted in the unit face will automatically adjust the intensity of the
push-button annunciator LEDs.
2.4.11 Unswitched inputs
J1, pin T is the unswitched input number 1 and J1 pin 17 is unswitched input 2. These inputs are presented
to the pilot and copilot regardless of the audio configuration, and will always mute the entertainment inputs.
These 510Ù inputs can be used for altimeter DH audio, GPS waypoint audio, autopilot disconnect tones,
air-to-ground (Flitefone) telephone ringer or any other critical audio signal. This input is not related to the
cellular telephone interface.
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 exter-
nal public address system to prevent feedback during transmissions.
2.4.13 Public Address Function (J2, Pin 18)
A PMA7000MS with serial numbers above “D” for the top board (second set of serial numbers) has a Pub-
lic Address function. 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 feedback.
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.
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 functionally
tested. All hardware is included.
2.4.15.1 Entertainment Input
N O T E : U s e t h e l o w l e v e l o u t p u t o f a n y e n t e r t a i n m e n t d e v i c e t o c o n n e c t t o t h e a u d i o
p a n e l . M a x i m u m s i g n a l l e v e l i s 2 V A C p - p .
D O N O T u s e a s p e a k e r - l e v e l o u t p u t , t h i s w i l l c a u s e i n t e r n a l d a m a g e i n t h e a u d i o p a n e l .
2.4.15.1.1 Stereo entertainment (7000S, 7000MS)