iET PRS-330 series, Operation Manual, Page: 51 / 67

MAINTENANCE
PRS-330 Series
39
R36 72.2 k Ω
R37 147.0 k Ω
R38 300.0 k Ω
R39 600.0 k Ω
R40 1.23 M Ω
R41 2.48 M Ω
R42 5.0 M Ω
R43 10.0 M Ω
During the adjustment process the fi rmware
cycles through each resistor and the technician
can enter the measured resistance value in
ohms. This should be done with a minimum
of 7 ½ digits of resolution. The accuracy of
measurement should be significantly more
accurate than the ±(70 ppm + 1 m
Ω ) for all
resistance values.
8.1.5 Calibration Menu and Process
To enter into the calibration process, press the
MENU key, push in the CAL ENABLE key
and keep pressed, and then select Instrument
Calibrate .
Figure 8-1 Main Menu with CAL ENABLE
pressed
Only when the CAL. ENABLE key is pressed
does the Instrument Calibration selection
become available.
Select Instrument Calibration and press
ENTER . The menu in Figure 8-2 will be shown.
Once this menu is displayed the CAL. ENABLE
key can be released.
Figure 8-2 Instrument Calibration Menu
Full Calibration allows calibration of 1 or all 43
resistors.
Trace Calibration is only required if the PRS-330
requires service which involves changing of the
relay board, or internal wiring between binding
post and the relay board. This compensates for
the buss wire resistance between the main board
and binding posts.
Calibration History allows the history of each
resistor to be reviewed showing resistance at
each calibration date.
8.1.6 Full Calibration (adjustment)
Full Calibration can be performed by selecting
Full Calibration and pressing the
ENTER key.
A password is required as shown in Figure 8-3.
Figure 8-4 shows entry of the password which is
IET . note tapping twice on the alpha keys will
select the second letter.
At the end of the process select all calibration
values will be saved into memory.
At anytime pressing the
MENU key will exit
calibration without making any changes.