HP 3478A, Technical Manual

Page: 48 / 150

TM 11-6625-3071-14
3478A
then the AUTO/MAN (3) button. Check the reading.
12. (Step #15.) Select the 3478A’s 5 Digit Display
by pressing the blue Shift button and then the
Downrange (5) button.
13. Remove the DC Volts Standard and Digital
Voltmeter from the 3478A and set the multimeter back
to the Single Trigger mode (press the SGL/TRIG
button).
s. (Step #15 and 16.) Short the 3478A’s HI and LO
INPUT Terminals. Set the instrument to the 30V Range.
t. Calibrate the 30V Range (applying zero and full
scale inputs) by using the procedure in steps e to 1. The
only exception is that the DC Volts Standard is set for an
output (in step i) of + 30V instead of + 30mV.
u. If no performance checks for the 30V range are to
be made, remove the DC Volts Standard and Digital
Voltmeter from the 3478A. Continue with step w.
v. If the performance checks for the 30V Range
are to be made, do the following:
1. Set the 3478A to the Internal Trigger Mode by
pressing the INT/TRIG button.
2. (Step #17.) Set the DC Volts Standard for a + 3V
output.
3. Using the Digital Voltmeter as the standard,
check and make sure the 3478A reading is within the
specified limits shown in Table 4-8.
4. (Step #18.) Set the DC Volts Standard for a +
IOV output. Check the reading on the multimeter.
5. (Step #19.) Set the DC Volts Standard for a +
30V output.
6. With + 30V applied to the 3478A, turn Autozero
off by pressing the blue Shift button and then the
INT/TRIG (AUTO/ZERO) button. Check and make
sure the reading is within 11 counts of the + 30V
calibration source.
7. (Step #20.) Turn Autozero on by pressing the
blue Shift button and then the INT/TRIG
(AUTO/ZERO) button.
8. Remove the DC Volts Standard and Digital
Voltmeter from the 3478A and set the multimeter back
to the Single Trigger Mode (press the SGL/TRIG
button).
w. (Step #20 and 21.) Short the 3478A’s HI and LOW
INPUT Terminals. Set the instrument to the 300V
Range.
x. Calibrate the 300V Range (applying zero and full
scale inputs) by using the procedure in steps e to I. The
only exception is that the DC Volts Standard is set for an
output (in step i) of + 300V instead of + 30mV.
y. If no DC Common Mode Rejection Test is to be
made, turn the output of the DC Volts Standard off and
remove it and the Digital Voltmeter from the 3478A.
z. If the DC Common Mode Rejection Test is to be
made, do the following:
1. Set the 3478A to the 30mV Range.
2. Connect a 1K ohm resistor (-hp- Part No. 0698-
1021) between the 3478A’s HI and LO INPUT
Terminals.
3. Note the 3478A’s reading.
4. With the DC Volts Standard’s output off, connect
the standard to the 3478A as shown in Figure 4-3.
5. Set the DC Volts Standard for 500V output and
then turn its output on. Check and make sure the
3478A’s reading is within .05OmV of the reading noted
in step 3.
6. Turn the DC Volts Standard’s output off and then
disconnect it from the 3478A. This completes the DC
Volts Test (and Calibration). If any test fails, go to
Section VII of this manual for troubleshooting.
4-90. DC Current Calibration and Test
4-91. Make sure the DC Volts Calibration and Test
(paragraph 4-86) has been done before doing the DC
Current Calibration and Test. Refer to Table 4-9 for the
DC Current Calibration Signals, Performance Test
Signals, and Performance Test Limits. Each step in the
table is shown in parenthesis in the procedure. All test
Signals are applied to the 3478A’s A (Amps) and LO
INPUT Terminals.
Table 4-9. DC Current Calibration and Test
4-15