Amptec Research 620A 4R, Operation And Maintenance Manual

D-1.

General Operation

A diagram and description of the front panel 
controls, connection instructions, and the theory 
behind resistance measurement is discussed in 
this section. This section of the manual contains 
complete operating instructions for the 
AMPTEC 620A 4R Igniter Tester.  

D-2.  Front Panel Features and Operation

Power Switch

When the front panel power switch is placed in 
the OFF/CHARGE position, all circuitry is 
removed from the Igniter Testers panel mount 
banana jacks, and the battery pack is connected 
to the charging circuit.  The battery charger may 
then be connected to the 620A-4R charging 
jack, in order to facilitate charging the batteries. 
For Safety reasons/purposes, when the power 
switch is placed in the “ON” position, the 
battery pack circuitry is disconnected from the 
charging circuit and the front panel charging 
jack.  

Range Switches

The AMPTEC 620A 4R input range is selected 
by depressing the desired range switch 
(protected with the given silicone rubber boot 
for water resistance) on the front panel. Just 
above each resistance range switch (silicone 
rubber boot covered) is a red L.E.D. which 
illuminates when any one of the four given 
ranges is selected. The pushbutton for the (20 
Ohm ) lowest resistance range is just below the 
display on the left, (see item 11 of the 620A 4R 
Front Panel Diagram.). When a given range is 
selected an indicator LED informs the user. Also 
note that 

a resistance range must be selected 

after first powering up

 the 620A 4R in  order to 

place it in an 

operational mode

, that is when 

first turned on a range must first be selected. If 
no range is selected upon first “powering up” 
the instrument may randomly set itself to a 
range that may not be desired until the operator 
selects the desired range. 

Calibration Access Screws

Around the perimeter of the 620A 4R front 
panel you will note there are 10 screws (phillips 
head type) that are used for calibration access. 
These screws are meant to remain intact and 
should only be removed by authorized 
personnel (i.e. Calibration Lab staff).

A 0.1 ohm resistor can be used to check the 
620A 4R’s zero offset. The AMPTEC 620A 
4R’s zero offset can be adjusted while the test 
leads are connected to the 0.1 ohm resistor. The 
620A 4R zero offset can be adjusted until the 
620A 4R display shows 0.1 ohms. (see the 
calibration chapter)   

Refer the AMPTEC 620A 4R to qualified 
service personnel (i.e Calibration Lab) if you 
suspect (i.e large error) the 620A 4R 
measurement display readings don’t agree with 
a test resistors value. Do not attempt to repair 
the 620A 4R unless you are qualified.

See Next Page for a Detailed 
620A-4R Front Panel Diagram

CHAPTER  D - OPERATION,  FUNCTIONAL 
SELF- TEST  AND  USE