TMA44 Audio Panel Installation Manual
7 November 2017
01849-00 Issue
AB
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Trig Avionics Limited
15
Included with this product is a power dropping resistor to be connected in
series with the power input, bottom connector, pin 43. This dropping resistor
is supplied for 28 volt systems so that unnecessary heat dissipation inside the
TMA44 can be avoided.
NOTE: To reduce the amount of heat dissipated in the audio selector
panel, when used in a 28 volt aircraft, a 15
, 15 watt dropping
resistor (p/n 701-015-1501) must be installed in series with the power
input. This resistor should be mounted to aircraft structure to
dissipate heat.
5.3.7
"Swap" Mode (J1 pin 11)
When a normally-open, momentary, push-button switch is connected between
pin 29 on the connector and aircraft ground, the user can switch between Com
1 and 2 by depressing this switch without having to change the mic selector.
This yoke mounted switch eliminates the need of removing your hands from
the yoke to change transceivers.
5.3.8
Backlighting (J1 pin 41)
The brightness of the green audio selection indicators is automatically
controlled by a photocell located in the centre of the unit. The brightness of
the buttons is set by the dimmer control input on pin 41. The unit has an
internal jumper to select between 14 volt and 28 volt electrical systems; when
shipped from the factory it is set to 14 volts. To change to 28 volts, follow the
instructions in section 5.3.9.
If the dimmer control is not connected, a constant low level illumination of the
buttons will be provided for night-time viewing.
5.3.9
Backlight Voltage Adjustment
As shipped from the factory, the TMA44 is configured for 14V dimmer
systems. For 28V dimmer systems remove jumper J9.
NOTE: Take precautions to prevent ESD damage prior to servicing unit
1.
Remove the 4 Phillips head screws from the TMA44.