LUDLUM MODEL 3, Technical Manual

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Model 3 Technical Manual
Section 7
Ludlum Measurements, Inc. Page 7-2 April 2016
SYMPTOM
no power (or meter
does not reach
BAT
TEST
or
BAT OK
mark) (continued)
nonlinear readings
meter goes full scale
or “pegs out”
POSSIBLE SOLUTION
3.
Check battery contacts. Clean them
with rough sandpaper or use an
engraver to clean the tips.
4.
Remove the can and check for loose
or broken wires.
1.
Check the high voltage (
HV
) using a
Ludlum Model 500 Pulser (or
equivalent). If a multimeter is used to
check the
HV
, ensure that one with
high impedance is used, as a standard
multimeter could be damaged in this
process.
2.
Check for noise in the detector cable
by disconnecting the detector,
placing the instrument on the lowest
range setting, and wiggling the cable
while observing the meter face for
significant changes in readings.
3. Check for “sticky” meter movement.
Does the reading change when you
tap the meter? Does the meter needle
“stick” at any spot?
4. Check the “meter zero.” Turn the
power
OFF
. The meter should come
to rest on 0.
1.
Replace the detector cable to
determine whether or not the cable
has failed, causing excessive noise.
2.
Check the
HV
, and if possible, the
input threshold for proper setting.