Calibration Procedures; Front Panel Inputs; Dc Volts Offset Calibration - HP 3457A Service Manual

3457A
Calibration
f. Lay the plug-in support assembly over the front panel to gain access t o the AC convertor frequency
response adjustment (Qain/Flatness A3C332).
g. Reconnect power to the instrument and turn it ON.
h. Run the AC Auto-Gal routine.
(Press the AUTO C A L corfiguratiort key, enter the rrurrrber 2 and press the E N T
key
1-
i. Enable Diagnostic Routine number 8.
(Press the Blue S H I F T key then the AUTO Z E R O
/
I)
configuration
key. Use the
4
scroll key t o display D I A G N O S T I C . Enter the number 8 and press the E N T key).
j Use an insulated adjustment tool to adjust A34332 (Qain/Flatness adj) until the display reads
PASSED 0 .
k. Exit the Diagnostic Routine.
(Press and hold the
+
/
R E S E T display key until a tone is heard).
1. Turn the instrument OFF and remove the power cord.
m. Replace the plug-in support assembly, top cover and terminal or terminal block assembly.
n. Reconnect power and turn the instrument ON.
5-19. CALIBRATION PROCEDURES
-
FRONT PANEL INPUTS
5-20. Calibration of the 3457A from the front input terminals consists of calibrating the offset and gain of
each range for the DCV, 2-Wire Ohms, 4-Wire Ohms and DCI Functions and gain of each range for the
ACV and ACI Functions. The FREQ Function is calibrated at one frequency.
The Preliminary Calibration Procedures shorild be completed before attempting
the following proct~drirrs.
5-21. DC Volts Offset Calibration
-
Front Terminals
5-22. Equipment Required. A low thermal short (copper wire) is required for this procedure.
a. Select the DC Voltage Function.
(Press the DCV function key).
b. Connect a short between the front panel
HI
and LO input terminals.
c. Use the following procedure to calibrate the front terminal offset on the 30 mV, 300 mV, 3
V,
30
V and 300 V ranges beginning with the 300 V range and ending on the 30 mV range.
1. Set the 3457A t o the appropriate voltage range.
(Use the
t
or
4
scroll key t o select the proper voltage
range).
2. Access the Calibration Command.
(Press the Blue S H I F T key, then the OFFSET C O M P
/
C configura-
tion key).
The display will show CAL
3. Enter the value of the input; in this case 0.
(NOTE: I f the security feature has not been disabled, (set t o
0 ) i t will be necessary t o enter the input value, the delimiter ( ) and the security code).