HP 6033A series Service Manual page 27

Load Effect (Load Regulation). Constant current load effect is the change in dc output current (Io) resulting from a
load-resistance change from short-circuit to full-load, or full-load to short-circuit. Full-load is the resistance which develops
the maximum rated output voltage at current Io. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-5. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to minimum.
b. Turn the unit's power on, and, using DISPLAY SETTINGS pushbutton switch, turn up voltage setting to full output.
c. Turn up output current to:
10Adc (6033A).
3Adc (6038A).
d. Increase the load resistance until the output voltage at +S and -S decreases to:
20Vdc (6033A).
60Vdc (6038A).
Check that the CC LED is lighted and AMPS display still reads ≈ 10 amps.
e. Short-circuit the load and allow the voltage across Rm to stabilize.
f. Record voltage across Rm.
g. Disconnect short across load.
h. When the reading settles (≈ 10s), record the voltage across Rm again. Check that the two recorded readings differ no
more than:
± 100µVdc (6033A).
± 530µVdc (6038A).
Source Effect (Line Regulation). Constant current source effect is the change in dc output current resulting from a change
in ac input voltage from the minimum to the maximum values listed in the Specifications Table in the Operating Manual.
Proceed as follows:
a. Connect the test equipment as shown in Figure 2-5. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to minimum.
b. Connect the unit to the ac power line through a variable autotransformer set for nominal line voltage.
c. Switch the unit's power on and turn up output voltage setting to full output.
d. Turn up output current to:
30Adc (6033A).
10Adc (6038A).
e. Increase the load resistance until the output voltage between + S and - S decreases to:
7.0Vdc (6033A).
20.0Vdc (6038A).
Check that the CC LED is still on.
f. Adjust autotransformer to the minimum for your line voltage.
g. Record the voltage across Rm.
h. Adjust autotransformer to the maximum for your line voltage.
i. When the reading settles record the voltage across Rm again. Check that the two recorded readings differ no more than:
90µVdc (6033A).
300µVdc (6038A).
PARD Ripple And Noise. Periodic and random deviations (PARD) in the unit's output (ripple and noise) combine to
produce a residual ac current as well as an ac voltage super-imposed on the dc output. The ac voltage is measured as
constant-voltage PARD, Page 23. Constant-current PARD is specified as the root-mean-square (rms) output current in a
frequency range 20Hz to 20MHz with the unit in CC operation. To avoid incorrect measurements, with the unit in CC
operation, caused by the impedance of the electronic load at noise frequencies, use a:
0.25Ω (6033A)
2.3Ω (6038A)
load resistor that is capable of safely dissipating 200 watts. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-9.
b. Switch the unit's power on and turn the output voltage all the way up.
c. Turn up output current to:
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