3M 701 User Manual

CALIBRATION AND VERIFICATION TEST PROCEDURE
FOR 3M 701 MEGOHMMETER
1. INTRODUCTION
This Specification defines the suggested method of calibration and
performance verification for the 3M 701 Megohmmeter. It also defines the
test equipment to be used.
2. TEST EQUIPMENT and DOCUMENTATION
A. A Keithley Model 619 Electrometer or equivalent (input impedance ≥ 1
x 10
9
Ω).
B. A decade box with a range of 1OOKΩ to 10GΩ ±1 % or the following
individual resistors:
100KΩ ±1%
1MΩ ±1%
100MΩ ±1%
100MΩ ±1%
1GΩ ±1%
10GΩ ±1%
C. Figure 1 - Calibration adjustments
Figure 2 - Main PC Board Assembly issue 1
Figure 3 - Main PC Board Assembly - issue 2
Figure 4 - Main PC Board Assembly - issue 3
3. VERIFICATION PROCEDURE
A. Place selector switch in the OFF position and adjust the mechanical
zero to the left end of the scale.
B. Place selector switch in the BATTERY TEST mode. Verify that pointer
is in the green (100V) area on the BATTERY TEST scale.
C. Place the 100KΩ resistor across the input. Switch the unit to
CONTINUITY TEST. Verify that the unit reads within limits (± 2° of
100KΩ mark on the CONTINUITY TEST scale. Short the input; verify
that the unit has full-scale deflection.
D. Remove the short; place the decade box across the input. Verify that
the unit reads within limits for 10GΩ and 1 MΩ in both the 10V and
100V SURFACE TEST modes. (Tolerances for the 1 MΩ / 10 GΩ

3M 701 Specifications

General

Category	Measuring Instruments
Accuracy	±5%
Display	LCD
Battery	9V battery
Operating Temperature	0°C to 50°C
Storage Temperature	-20°C to 60°C

Summary

Introduction to 3M 701 Megohmmeter

Test Equipment and Documentation

Keithley Model 619 Electrometer

Required electrometer or equivalent with specified input impedance for testing.

Decade Box and Resistors

Decade box or individual resistors (100kΩ to 10GΩ) for calibration and verification.

Reference Figures for Calibration

Figures illustrating calibration adjustments and PC board assemblies.

Verification Procedure

Mechanical Zero Adjustment

Set selector to OFF and adjust mechanical zero to the left end of the scale.

Battery Test Verification

Check pointer in the green area of the BATTERY TEST scale.

Continuity Test Verification

Verify 100kΩ resistor reading and full-scale deflection with a short.

Surface Test Mode Verification

Verify 10GΩ and 1MΩ readings in 10V and 100V SURFACE TEST modes.

Output Voltage Verification

Verify Keithley 619 output is 93V-107V in 100V SURFACE TEST mode.

Calibration Procedures

Initial Calibration Setup

Install batteries and set selector to BATTERY TEST position.

R10 Adjustment for Voltage Output

Adjust R10 for 10.00V ± 0.01V between U2 Pin 7 and ground.

R23 Adjustment for High Voltage

Adjust R23 for 100.0V ± 0.1V between SW1 Pin 12 and ground.

R21 Adjustment for Full Scale

Adjust R21 for full-scale pointer reading in 100V SURFACE TEST mode.

R36/R8 Adjustment for Battery Scale

Adjust R36 (or R8 for Issue 1) for 100V mark on BATTERY TEST scale.

Final Resistance Verification

Verify resistance readings (100kΩ-10GΩ) in 10V and 100V SURFACE TEST modes.

Continuity Test Final Check

Confirm proper readings with short and 100kΩ in CONTINUITY TEST mode.