HP 3457A Service Manual page 134

Calibration 3457A
a. Remove the two screws attaching the Strain Relief/Wiring Block Assembly to the rear panel and
disconnect it from the instrument. (Refer to Figure 5-3, Step 1).
b. Remove the Strain Relief Plate from the bottom of the Strain Relief Assembly (Figure 5-3, Step 2).
c. Remove the Wiring Block from the Strain Relief Housing (Figure 5-3, Step 3).
d. Install copper shorting wires from INput HI to INput LO, from INput HI to Q Sense HI, and from
INput LO to Q Sense LO on 4-Wire Q input channel 10. Securely tighten the appropriate retaining
screws. (Refer to Figure 5-4 for wire connections).
e. Connect the prepared Wiring Block Assembly to the HP 44491A General Purpose Relay Assembly.
SHORTING WIRES
4 WIREQ
| LARS | 7-4
T
2 WIRE 44491A RELAY
Figure 5-4. 44491A Wiring Block Connections
5-58. DC Volts Offset Calibration - HP 44491A
5-16
a. Select the DC Voltage function. (Press the DCV function key ).
b. Select the Scanner Input. (Press the TERM configuration key, enter the number 2 and press the ENT key ).
c. Select channel 0. (Press the CHAN configuration key, enter the number 0 and press the ENT key ).
d. Use the following procedure to calibrate the DC offset on the 300 V, 30 V, 3 V, 300 mV and
30 mV ranges beginning with the 300 V range.
1, Set the 3457A to the appropriate range. (Use the { or | scroll key's to select the proper range).
2. Access the Calibration Command. (Press the Blue SHIFT key, then the OFFSET COMP / C configura-
tion key). The display will show CAL.
3. Enter the value of the input - in this case 0. (NOTE: If the security feature has not been disabled (set to
0), it will be necessary to enter the input value, the delimiter (, ) and the security code).
4. Press the ENT key. The display will show CALIBRATING while the calibration routine is
running.