22. TRIM controls
A continuous rotary control allowing the input gain to be t/-10dB about its nominal value. In LINE mode
this may be used to accommodate both consumer and professional levels, while in MIC mode the unit may be
adapted (“on-the-fly” if necessary) to different user and microphone characteristics.
23. General Purpose Input & Output Controls (GPIO)
This 25 pin D connector provides interconnectivity to external equipment. There are 6 relay outputs and 7 loop
input circuits. The 6 relay outputs provide indication when the 3 mic circuits are on and when the 3 talkback/
intercom circuits are on. The 7 inputs provide external control of the 3 mic on circuits, a global off air control, and 3
inputs for illuminating the 3 incoming intercom source LEDs.
Switch Options
Units supplied after June 2008 are fitted with enhanced firmware that allows the operation of some front panel
controls to be altered by the user. This allows the functionality of the unit to be tailored to meet changing
requirements and fulfil different tasks. Older units can be retro fitted with this software.
Changes are made by holding down specific combinations of front panel buttons
as power is applied to the unit
.
For safety reasons the unit only responds to change instructions at the moment of power-up and applying the
switch combinations at any other time will have no effect other than the usual functions of the switches involved.
Combinations of switches other than those detailed below are ignored.
Only one change may be made at a time – to make multiple changes, remove power from the unit after each
change then reapply it while holding down the next switch combination required. Apart from the restrictions
described, the number of changes is unlimited and they may be applied at any time.
The unit configuration is stored in internal non-volatile memory and retained even when the unit is unpowered.
Supported options:
-
Holding both C ON and TALK3-C selects normal operation of the TB switches, whereby brief depressions
of the switches toggle talkback on and off and longer presses engage talkback for only as long as the
switch is pressed. This is the default mode of operation.
-
Holding both C ON and TALK4-C selects momentary-only operation of the TB switches, whereby talkback
is only engaged for as long as the switch is pressed.
-
Holding both C ON and TALK5-C selects latching-only operation of the TB switches, whereby each
depression of the switch, however long or short, toggles talkback from on to off or vice versa.
-
Holding both C ON and B ON toggles whether the channel A and C microphone signals are muted when
one of their corresponding talkback channels is active. The default mode of operation is for muting to be
enabled.
A Further firmware revision was made to allow the switch operation of the Talkback and Microphone circuits to be
linked together. This firmware is fitted to all versions with a serial no: 642 or higher.
-
Holding both A ON and C ON allows the A & C mic switches to be linked.
-
Holding both TALK3-A and TALK3-C allows the TALK3 switches to be linked.
-
Holding both TALK4-A and TALK4-C allows the TALK4 switches to be linked.
-
Holding both TALK5-A and TALK5-C allows the TALK5 switches to be linked.
-
Holding both B ON and TALK3-A allows the B ON switch to toggle all the switches between linked switches
and normal operation. When in this mode if the B ON switch is on then any pairs of switches that have
been set to be linked will operate in the linked mode and if the B ON switch is off then these same switches
will operate individually.
-
NOTE: The above programming operations 'toggle' between turning the facility on and off.
