D-7.
Battery Monitoring Circuitry
The 630 series igniter tester display has a ±
polarity display indicator preceding the
unit’s regular 4 ½ digit numeric display.
The negative polarity display LED (see
item 6 of the 630 series igniter tester Front
Panel Diagram) is used as a Low Battery
indicator.
If the low battery LED is illuminated, 630ES
readings should not be trusted. An
overnight recharge should be performed
before using the 630 series igniter tester for
critical testing.
It is possible for the user to receive a low
battery indication on a single range only
(particularly the 20 ohm range), while the 630
series igniter tester remains well within
operating limits on other ranges.
Unless the
user observes a continuous low battery
indication during measurement, readings
are still valid.
Notice for Cal Lab:
The variable
potentiometer - RV3 is factory adjusted to
have the low battery indicator come on at
4.50 VDC. To make this adjustment, and
remove the fuse
from the fuseholder. With
an adjustable DC power supply, set the
power supply output to be 4.50 VDC. Be
sure to observe power supply polarity.
Connect the power supply to the test points
labeled “
MAIN
” + pos. and - neg. located
in the rear section of the 620A MAIN PCB.
(i.e po power supply output to the
anode side). Adjust trimpot RV3 to have the
low battery indicator just come on (negative
sign on display). An increase in power
supply voltage to 4.52 VDC should have the
low battery indicator go out. Finally,
disconnect the power supply, and return the
fuse to the fuse holder in the rear panel.
D-8 Zero Pot
The Zero Pot on the 630 series igniter tester
Front panel (see item #8 on 630 series
igniter tester Front Panel Diagram) is used
to adjust linearity, which effectively adjusts
the “zero” of the meter. The zero can be
adjusted using the “zero knob” per the
maintenance section of this manual. The
zero knob can also be used to counteract the
2 wire resistance offset encountered with
some test lead harnesses. Checking the
630ES “zero offset” should be one of the
first items a user does if one encounters an
unusual or unexpected resistance level.
