720A Operation and Maintenance Manual – Rev S – January 25, 2019
Page 24
13231 Rooster Springs Rd.,
Austin, TX 78737
T:
(512) 858-4045
E:
amptec.com
If you or another authorized individual would like to replace the batteries in a 720A
meter without sending the unit to our facility, please contact AMPTEC for information on
how to complete this process.
E-3.2 Current Source Diagnostic Test Routine
The following steps can help determine if the current source circuitry is faulty:
1) Select the 2
Ω
Range.
2) Put output leads across a 1
Ω resistance standard (0.005% or better).
3) Measure the voltage drop with a DC Voltmeter. It should be 0.100V.
If the above test proves untrue, then the current source circuitry is possibly faulty and
may need replacing. See section E-2 for more information about sending your product
in for repair.
E-3.3 Digital Voltmeter (DVM) Test Routine
The following steps can help determine if the DVM circuitry is faulty:
1) Select the 200 m
Ω
Range.
2) Short the output leads.
3) Check for a reading of 0.000 (± 5 counts).
4) Put the output leads across a 0.100
Ω resistance standa
rd.
5)
The display should read 100.00 mΩ
(± 10 counts depending on the resistor’s
accuracy).
If the above test proves untrue, then the DVM circuitry is possibly faulty and may need
replacing. See section E-2 for more information about sending your product in for repair.
E-4 720A Calibration Procedure Overview
This section of the manual contains information regarding calibration of the AMPTEC
720A Digital Micro-Ohmmeter. Total calibration of your instrument should be performed
on a regular basis to ensure continued accuracy. The recommended calibration interval
is 1 year, but the unit may be calibrated more often if desired. When calibrating the
720A meter, the unit should warm up for at least 30 minutes prior to calibration. If
battery powered, the unit should be fully charged. If possible, the unit should ideally be
calibrated in a room with optimal ambient temperature (21º - 25 º C), optimal humidity
(37% - 42%), and minimal RF interference.
Please note that opening of the unit in any fashion (including doing so to complete the
calibration procedure) will void the unit’s warranty, so if there are concerns about
voiding the warranty it is best to return the unit to AMPTEC’s facility for recalibration.
More detailed instructions on how to begin the calibration procedure of your unit will
commence on the following page.
