4
Contents
1. GENERAL DESCRIPTION ................................................................ 5
2. INITIAL ADJUSTMENTS ................................................................... 5
3. RANGE SELECTION ........................................................................ 5
4. ZERO ADJUSTMENT ....................................................................... 6
5. MEASURING THE RESISTANCE ...................................................... 6
5
1.
GENERAL DESCRIPTION
The Simpson Ohmmeter Model 372 Series 2, V2 is a six range instrument. It
measures values from 0.2
⍀
to 50 M
⍀
with an accuracy of ±3% of arc.
For in-circuit measurements, turn off circuit power and discharge capacitors be-
fore taking measurements. Small residual voltages can affect accuracy of mea-
surements and greater voltages can damage the Instrument.
Study the circuit under test before making any measurements to determine if the
voltage or current supplied by the Model 372 (see Table 3-1) can cause damage
or changes in any of the associated components (transistors, diodes, filaments,
low voltage capacitors, I.C.’s, etc.).
DO NOT
use this Instrument to test explosive devices or circuits.
2.
INITIAL ADJUSTMENTS
1.
Place the ohmmeter in the desired operating position with the test leads
disconnected.
2.
Observe the pointer position, then turn the zero adjust screw on the face of
the meter until the pointer rests directly over the division to the right of the
infinity (
) mark on the meter scale. (This is a mechanical adjustment for
meter movement zero.)
3.
RANGE SELECTION
Set the range selector switch to the desired range. For optimal results choose a
range for a pointer deflection near center scale. Ranges, center scale readings,
maximum test currents, and open circuit voltages are given in the table below for
reference.
Table 3-1
Max. D.C. Test
Ohms
Ohms
Max. D.C. Test
voltage* (Open
Range
Center
Current At Zero
:
:
:
:
:
Circuit)
RX1 (0-500
:
:
:
:
:
)
5
:
:
:
:
:
300 mA
1.5V
RX10 (0-5 K
:
:
:
:
:
)
50
:
:
:
:
:
30 mA
1.5V
RX100 (0-50 K
:
:
:
:
:
)
500
:
:
:
:
:
3 mA
1.5V
RX1000 (0-500 K
:
:
:
:
:
)
5 K
:
:
:
:
:
0.3 mA
1.5V
RX10k (0-5 M
:
:
:
:
:
)
50 K
:
:
:
:
:
0.03 mA
30V
RX100k (0-50 M
:
:
:
:
:
)
500 K
:
:
:
:
:
0.003 mA
30V
Zero Ohms adjust control set properly for the above readings
*Nominal battery voltage of a new battery may be slightly higher
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