720A Operation and Maintenance Manual – Rev S – January 25, 2019
Page 11
13231 Rooster Springs Rd.,
Austin, TX 78737
T:
(512) 858-4045
E:
amptec.com
If your unit has autorange, you can still use the range switches to manually select your
range of measurement. Simply press the appropriate range switch and the unit will exit
autorange mode. For more information on how the autorange feature works along with
the range switches, please visit section D-2.5 on the following page.
D-2.3 Display
The unit features a 4 ½ digit red LED display (refer to item 3 within
Figure 1
on page 9).
The unit’s display should engage and light up automatically when the unit is turned on.
All resistance measurements made by the unit are presented on this display up to
20,000 counts. The 720A’s display is durable and high quality, meaning it should have a
life lasting many years. Should the display become damaged or stop operating properly,
it can be replaced at an AMPTEC facility.
D-2.3.1 Low Battery Indicator
This feature is only present in the 720-BAT version of the 720A meter. The above
Figure 3
demonstrates the low battery indicator on the unit’s front panel. Whenever the
unit’s batteries are nearly depleted (having only 4V or less of remaining power) the unit
will indicate this with a dash appearing on the leftmost LED of the display. Once the
unit’s low battery indicator is triggered, the unit has approximately 30 minutes of usage
left before the batteries will be entirely depleted.
D-2.3.2 Overload/Overrange Indicator
If you attempt to take a measurement that is too high for the range you have selected,
the unit will enter overrange mode. An example of this would be if you were to attempt
measuring 500 mΩ on the 200 mΩ range. The unit’s way of letti
ng the end user know
that it is not in the correct range to take a measurement will be to enter overrange
mode. Once in overrange mode, this will be indicated by the display flashing four zeros
on the screen. The unit will automatically exit overrange mode if you press the
appropriate range switch for the measurement being taken.
If your unit has the autorange feature it will automatically select the appropriate range of
measurement and will not enter overrange mode unless you are attempting to take a
resistance reading over 200 KΩ.
Figure 3
Low Battery Indicator on 720A Front Panel
