SBS AT10.1 SERIES, Operating And Service Instructions

Page: 40 / 104

OPERATING THE AT10.1
34
Adjusting Ground Detection Sensitivity
The AT10.1 ground detection alarm
sensitivity is adjustable from 5 to 30 k
Ω
. You
must have a small jeweler's screwdriver for
adjustment, along with a "test resistor" whose
Ohmic value is sized for the required ground
sensitivity.
The ground detection sensitivity is adjusted
equally (+/-) from 5 to 10 k
Ω
, but slightly less
equally from 10 to 30 k
Ω
. Adjustments are
made via potentiometer labeled RA3 SENS ,
located on the Main Control PC Board (A1),
as shown in the figure at the right.
NOTICE
Do not try to adjust the upper potentiometer labeled RA2
BALANCE . This adjustment is made at the factory for proper
circuit operation.
!
CAUTION
Before connecting or disconnecting a test resistor to the AT10.1,
de-energize and lock out all ac and dc voltage sources.
Check with a voltmeter before proceeding. Restart the AT10.1
only when necessary to make the sensitivity adjustment. If your
battery is grounded, do not attempt this procedure.
Remove the Plexiglas safety shield
at the I/O panel board. Connect the
test resistor between
TB1(+)
and
ground.
Adjust
RA3
counter-clockwise
until the front panel indicator goes
out, then adjust clockwise until the
POS GND
indicator just lights.
Make this adjustment slowly, since
the indicator is only updated once
every 4 seconds.
De-energize and lock out power to the AT10.1. Remove the test resistor
at
TB1(+) and verify the POS GND indicator goes out. Connect the test
resistor between
TB1(-)
and ground. Verify that the
NEG GND
indicator
lights. If not, adjust RA3 clockwise until it just does.
Remove the test resistor and return the AT10.1 to normal operation.