57
Vega’s C-
6124
Crosspatch squelch enabled
JP2
B
Crosspatch squelch disabled
JP2
A
7.3.5 PARALLEL LINE OFF-HOOK
The green LED in the Instant PTT switch on the front panel of the Switch Bus Module will light when a
parallel line is off-hook. PSTN lines usually stay at –48VDC when on-hook. During the off-hook condition
the line voltage will drop to about –10VDC. The Parallel off-hook detector will activate when this line
voltage is less than –25VDC. If the PLM is connected to a PABX which works off a lower voltage (-24VDC
typical) the parallel line detect will stay lit.
7.4 LEVEL ADJUSTMENTS
The above figure shows a top view and side view of the PLM card with the adjustment points labeled. The
side view is the view one would have if the back cover of either the Switch Bus Module (SBM) or the End
Bus Module (EBM) were removed for card adjustments. The potentiometers that are most likely to be
adjusted are available without taking the card out of the chassis.
RV14
RV9
RV4
RV1
TP9
TP11
RV3
TP17
RV2
RV8
TP3
TP12
TP6
TP2
RV13
RV12
RV11
RV10
TP10
RV1: RX INPUT LEVEL
TP9: RX INPUT LEVEL
RV4: TX OUTPUT LEVEL
TP10: TX MONITOR LEVEL
RV9: LAM LEVEL
RV14: RECORDER OUTPUT
