Installation

VM102 MASTER STATION ADJUSTMENTS
SETTING PRESET INTERCOM AUDIO LEVELS
Set the slide volume controls at all Room Station to approximately level "4."
Disconnect speaker at Door Station.
Adjust VR2 at Door Station so that the chime rings at an acceptable level at the Room
Stations.
Reconnect Speaker at door.
Adjust VR1 on the Door Station, so the chime rings quietly at the Door Station.
Adjust the blue hand fitted trim pot on Master Intercom PCB (above and to the right of the
Master speaker) so the chime rings at the same level at the Master as it does at the Room
Stations.
MICROPHONE GAIN
Microphone Gain is adjusted by means of a miniature trim-pot on the Intercom PCB, which
is the PCB above and to the right of the speaker, on the rear of the Master fascia.
The trim-pot is labelled VR2 and is located towards the top of the PCB.
This pot is normally set to 50% and will rarely require adjustment.
Adjustment will only be necessary on larger systems (15 to 20 stations) where the
accumulated loading effects of all the Room Stations will result in lower communication
levels.
Where adjustment is necessary, use the correct flat bladed screwdriver with a blade width
of between 2 and 2.5mm to avoid damaging the pot.
There are no detectable start and stop positions on this pot, which means that it can be
unknowingly rotated past maximum, where it immediately returns back to minimum.
The best way to adjust this pot to maximum is by measuring its resistance with an ohmmeter,
with power to the system turned off.
The resistance can be measured across the bottom two pins of the pot.
The resistance reading of the pot in the standard 50% position is typically between
2200 and 2300 ohm.
While measuring the two bottom pins of the pot, rotate the pot clockwise until its resistance
reads between 10 and 100 ohm. This position represents maximum microphone gain.
NOTE: Where this pot requires adjustment, the same adjustment is normally done at all
other stations on the system, including the Door Station.
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