Front Panel Controls; Status Bar Of Leds; Link Switch; Override Button - Pro Intercom MS300 Instructions

The left section of the front panel contains controls which affect all circuits.
The 'mains' switch connects or completely disconnects the MS300 from the AC source.
The 4-pin male XLR is used to connect a headset, a handset or a gooseneck microphone.
Pins 1 & 2 are the input, with pin 1 being ground. Pins 3 & 4 are the output with pin 3 being
'low'. When a gooseneck microphone is being used, the speaker and controls on the right
side of the chassis are used to listen. Communication is duplex, simultaneous talk/listen no
matter what device is connected. If a handset is used and it has a push-to talk bar, the bar
should be locked On or internally wired for constant On. If a gooseneck microphone is used,
particular attention should be paid to instructions regarding Sidetone, below.
The Status Bar of LEDs contains four green LEDs. The top LED indicates that the power
supply section of the MS300 is delivering 24VDC to the operating section. The green LEDs
below it are bi-color and turn red if there are any problems on Circuits A, B or C. The
most likely problems are a short circuit between the power pin (2) and ground in one of
the interconnecting cables, or a pin 1/3 reversal in the wiring which often happens when
attaching different gender connectors to opposite ends of a cable. The fact that a microphone
cable works with a microphone does NOT assure that it will work in an intercom system. An
out-of-phase microphone will still work, if poorly. An out-of-phase intercom system will not
work at all and may damage components. If the problem on the circuit is serious enough
to damage the MS300, the circuit will shut down until the problem is removed. The other
circuits will not be affected.
Below the status bar is a switch which allows you to link the circuits, either A+B or ALL.
This will put all the stations on the linked circuits on a common circuit as may be desirable
during a sound check or rehearsal. The normal position is Off.
Above and to the right of the Link switch is a button marked Override. Pro Intercom
Loudspeaker stations have a built-in circuit which restores their front panel controls to
preset functions, regardless of how they may have been adjusted locally. Units turned Off
are turned On, volume is restored to an audible level, etc., all determined by internally set
jumpers. The Override button activates that circuit. For example, a Loudspeaker station that
has been turned down locally could have its volume restored and an important message
heard.
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