Agilent Technologies 6612B, Service Manual, Page: 15 / 74

Verification and Performance Tests - 2
15
CV Source Effect
This test measures the change in output voltage that results from a change in ac line voltage from the minimum to
maximum value within the line voltage specifications.
a. Turn off the supply and connect the ac power line through a variable voltage transformer.
b. Connect the output as shown in Figure 2-1a with the DVM connected between the +S and the -S terminals. Set
the transformer to nominal line voltage.
c. Turn on the supply and program the current to the maximum programmable value and the output voltage to the
full-scale value .
d. Adjust the load for the full-scale current value as indicated on the front panel display. The CV annunciator on
the front panel must be on. If it is not, adjust the load so that the output current drops slightly.
e. Adjust the transformer to the lowest rated line voltage (e.g., 104 Vac for a 115 Vac nominal line voltage input).
f. Record the output voltage reading on the DVM.
g. Adjust the transformer to the highest rated line voltage (e.g., 127 Vac for 115 Vac nominal line voltage input).
h. Record the output voltage reading on the DVM. The difference between the DVM reading is steps (f) and (h) is
the source effect voltage and should not exceed the value listed in the performance test record chart for the
appropriate model under CV SOURCE EFFECT.
CV Noise (PARD)
Periodic and random deviations (PARD) in the output (ripple and noise) combine to produce a residual ac voltage
superimposed on the dc output voltage. CV PARD is specified as the rms or peak-to-peak output voltage in the
frequency range specified in the User’s Guide.
a. Turn off the supply and connect the output as shown in Figure 2-1a to an oscilloscope (ac coupled) between the
(+) and the (-) terminals. Set the oscilloscope's bandwidth limit to 20 MHz and use an RF tip on the oscilloscope
probe.
b. Turn on the supply and program the current to the maximum programmable value and the output voltage to the
full-scale value.
c. Adjust the load for the full-scale current value as indicated on the front panel display.
d. Note that the waveform on the oscilloscope should not exceed the peak-to-peak limits in the performance test
record chart for the appropriate model under CV NOISE (PARD).
e. Disconnect the oscilloscope and connect an ac rms voltmeter in its place. The rms voltage reading should not
exceed the RMS limits in the performance test record chart for the appropriate model under CV NOISE
(PARD).