Simpson 372-3 User Manual

Model 372

Series 3 Ohmmeter

INSTRUCTION MANUAL

About this Manual

To the best of our knowledge and at the time written, the information contained
in this document is technically correct and the procedures accurate and adequate
to operate this instrument in compliance with its original advertised specications.

Notes and Safety Information

This Operator’s Manual contains warning headings which alert the user to check for
hazardous conditions. These appear throughout this manual where applicable and
are dened below. To ensure the safety of operating performance of this instrument,
these instructions must be adhered to.

Warning, refer to accompanying documents.

Caution, risk of electric shock.

Technical Assistance

SIMPSON ELECTRIC COMPANY oers assistance Monday through Friday,
8:00 am to 4:30 pm Central Time. Contact Technical Support or Customer
Service at [phone] or visit our website at http://www.simpsonelectric.com

Warranty and Returns

SIMPSON ELECTRIC COMPANY warrants each instrument and other articles manu­factured by it to be free from defects in material and workmanship under normal use
and service, its obligation under this warranty being limited to making good at its
factory or other article of equipment
such instrument or other article of equipment to the original purchaser be returned
intact to it, or to one of its authorized service centers, with transportation charges
prepaid, and which its examination shall disclose to its satisfaction to have been
thus defective; this warranty being expressly in lieu of all other warranties expressed
or implied and of all other obligations or liabilities on its part, and SIMPSON
ELECTRIC COMPANY neither assumes nor authorizes any other persons to assume for
it any other liability in connection with the sales of its products.

This warranty shall not apply to any instrument or other article of equipment which
shall have been repaired or altered outside the SIMPSON ELECTRIC COMPANY
factory or authorized service centers, nor which has been subject to misuse, negli­gence or accident, incorrect wiring by others, or installation or use not in accord with
instructions furnished by the manufacturer.

This manual represents your meter as manufactured at the time of publication. It
assumes standard software. Special versions of software may be tted, in which
case you will be provided with additional details.

which shall within one (1) year after delivery of

The apparatus has been designed and
Requirments for Electrical Equipment for Measurement, Control and Laboratory Use.”
This operating guide contains information and warnings that must be followed by
the user to ensure safe operation and to maintain the apparatus in a safe condition.

We reserve the right to make changes and improvements to the product without
obligation to incorporate these changes and improvements into units previously
shipped.

tested in accordance with EN 61010-1, “Safety

2

SHOCK HAZARD: As

Requirements for Electrical & Electronic Measuring & Controlling Instrumenta­tion, a shock hazard shall be considered to exist at any part involving a potential

in excess of 30 volts RMS (sine wave) or 42.4 volts DC or peak and where a
leakage current from that part to ground exceeds 0.5 milliampere, when mea­sured with an appropriate measuring instrument
ANSI C39.5.

NOTE: The proper measuring instrument for the measurement of leakage cur­rent consists essentially of a network of a 1500 ohm non-inductive resistor shunted
by a 0.15 microfarad capacitor connected between the terminals of the measur­ing instrument. The leakage current is that portion of the current that
the resistor. The Simpson Model 229-Series 2 AC Leakage Current Tester meets
the ANSI C39.5 requirements for the measurement of AC leakage current and
can be used for this purpose. To measure DC Leakage current, connect a 1500
ohm non-inductive resistor in series with a Simpson 0-500 DC microammeter
and use this as the measuring instrument.

in American National Standard, C39.5, Safety

in Section 11.6.1 of

through

3

Contents

1. GENERAL DESCRIPTION

2. INITIAL ADJUSTMENTS...................................................................

3. RANGE SELECTION ........................................................................

4. ZERO ADJUSTMENT .......................................................................

5. MEASURING THE RESISTANCE ......................................................

...............................................................

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6
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1. GENERAL DESCRIPTION

The Simpson Ohmmeter Model 372 Series 3 is a six range instrument. It
measures values from 0.2

For in-circuit measurements, turn

.

to 50 M

with an accuracy of ±3% of arc.

circuit power and discharge capacitors
before taking measurements. Small residual voltages can
measurements 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,
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

) mark on the meter scale. (This is a mechanical adjustment for

(

meter movement zero.)

of

3. RANGE SELECTION

Set the range selector switch to the desired range. For optimal results choose a
range for a
maximum test currents, and open circuit voltages are given in the table below for
reference.

Range

RX1

RX10

RX100

RX1000

RX10K

RX100K

Zero Ohms adjust control set properly for the above readings
*Nominal battery voltage of a new battery may be slightly higher

near center scale. Ranges, center scale readings,

Table 3-1

Center

(Ohms)

5

50

500

5 K

30 K

300 K

Maximum Current

(Zero Ohms)

340mA

30mA

3mA

0.3mA

0.65mA

65μA

Maximum Voltage

(Open Circuit)

1.5V*

1.5V*

1.5V*

1.5V*

21.5V

21.5V

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4. ZERO ADJUSTMENT

1. Insert test leads into ohmmeter jacks and short lead tips together.

2. Adjust ZERO OHMS control until the pointer rests over the zero division on
the meter scale.

NOTE: When the meter can no longer be adjusted to zero on the RX1 through
RX1000 ranges, replace the Size “C”, 1.5V battery. When the meter can no longer
be adjusted to zero on the RX10,000 or RX100,000 ranges, replace

18V battery pack, Simpson Part Number 00840.

5. MEASURING THE RESISTANCE

1. The Model 372 Ohmmeter incorporates two scales.

a) The top scale (Black) is used for the 0-500Ω, 0-5KΩ, 0-50KΩ, 0-500KΩ ranges.
Center Scale values are : 5Ω, 50Ω, 500Ω, 5KΩ respectively.
b) The Bottom Scale (Green) is used for the 0-5 MegΩ and 0-50 MegΩ ranges.
Bottom Center Scale values are 30KΩ and 300KΩ respectively.

2. Attach the test leads across the component to be measured. Read value
indicated on the meter scale and multiply reading by the appropriate factor
for the range selected to obtain the actual resistance.

3. For best results, select the range in order that the attained readings are near
mid scale.

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NOTES

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SIMPSON ELECTRIC COMPANY

520 Simpson Avenue, Lac Du Flambeau, WI

[phone] FAX [phone]

www.simpsonelectric.com

Printed in U.S.A. Part No. 06-114979 Edition 8, 12/11