F-1.
General
This section of the manual contains routine
maintenance information regarding the
AMPTEC RESEARCH 620LM Igniter tester.
Calibration should be performed on a regular
basis to ensure continued instrument accuracy
or following a main PCB electronic component
repair/replacement. The recommended
calibration interval is 1 year.
The AMPTEC 620LM igniter tester is a four
wire Kelvin ohmmeter.
The AMPTEC
Igniter Tester must be calibrated using four
wire Kelvin connections to the resistance
standard
in order to eliminate lead resistance
and contact resistance errors. The rear panel
terminal strip (
V
high,
I
high,
V
low,
I
low) 4-wire
configuration must be maintained up to the
point of the connection to the resistance
standard (for any range below 200Kohm).
F-2.
Required Test Equipment
Following standard resistors are required to
calibrate the 620LM Igniter Tester .
Precision Resistors:
0.01 ohm ± 0.01% Accuracy or better
1.0 ohms ± 0.005% Accuracy or better
10 ohms ± 0.005% Accuracy or better
1.0 Kohm ± 0.005% Accuracy or better
10 MegOhm ± 0.10% Accuracy or better
14 Kohm ± 0.10% Accuracy or better
Test Leads:
Rear panel connected 4-wire Kelvin Test
Lead wiring (
V
high,
I
high,
V
low,
I
low) is
needed to eliminate in-series resistance errors or
offsets (for calibration and accuracy purposes).
F-3.
Calibration Procedure
The AMPTEC
620LM should be calibrated but
first it should be allowed to
warm-up
for a
minimum of
15 minutes
before beginning the
calibration procedure.
620LM
The calibration trimpot adjustments are
accessed by removing the screws in the feet of
the unit, then lifting off the lid. This provides
access to the main PCB trimpots. The locations
of the adjustments are shown on drawing
number 620-600 at the back of this manual. The
meter’s ranges are selected via (computer
command) the optically isolated RS232C serial
interface.
F-3-1. Zero Offset Adjustment
(20 ohm and
higher ranges)
1.
Connect the rear panel 4 Wire Kelvin
measurement leads to the 10 ohm standard
resistor. Using the RS232C interface
(commands) select the 2 KOhm range.
2.
Adjust potentiometer RV2 for a display
indication of 0.0100 KOhms .
Do not over
adjust RV2 past a 0.0100 reading
.
F-3-2. Full Scale Adjustment
(20 ohm and
higher ranges)
1.
Still on the 2.0 Kohm range. Connect the
Kelvin leads to the 1.0 Kohm standard resistor.
2.
Adjust RV1 for a display reading of 1.0000
Kohm.
F-3-3 2.0 ohm range Zero adjustment
1.
Using the RS232C interface (commands)
select the 2 ohm range. Connect the 4 wire
Kelvin leads to the 0.01 ohm standard resistor.
2.
Adjust potentiometer RV5 for a display
indication of 0.0100 Ohms .
F-3-4. 2 ohm range Full Scale Adjustment
1.
Select the 2 ohm range. Connect the rear
panel
test leads or wiring to the 1.00 ohm standard
resistor.
2.
Adjust
RV6
for a display reading of 1.0000
Ohm.
