Agilent Technologies E3620A Service Manual download pdf (Page 9)

A-3

to the full rated value of power supply.

b. Connect the unit to the ac power line through a variable

autotransformer which is set for low line voltage(104 Vac for

115 Vac).

c. Turn the unit's power on and turn CURRENT control fully clock-

wise.

d. Turn up output voltage to the full rated value as read on the dig-

ital voltmeter.

e. Record the output voltage at the digital voltmeter.

f. Adjust autotransformer to high line voltage(127 Vac for 115

Vac).

g. When the reading settles, record the output voltage again.

Check that the two recorded readings differ no more than

0.01% of output voltage plus 2 mV.

Load Transient Recovery Time

Definition: This is the time for the output voltage to return to within a

specified bend around its voltage following a step change in load.

Test Parameter:

Measured Variable: Output Voltage Transients

Expected Results: Less than 50 usec (at 10 mV from base line)

Test Procedure:

a. Connect the test equipment as shown in Figure A-2, but

replace the DVM with the oscilloscope. Operate the electronic

load in constant current mode.

b. Turn the unit's power on and turn CURRENT control fully clock-

wise.

c. Turn up output voltage to the full rated value.

d. Set the electronic load to transient operation mode between

one half of unit's full rated value and unit's full rated value at a 1

KHz rate with 50% duty cycle.

e. Set the oscilloscope for ac coupling, internal sync and lock on

either the positive or negative load transient.

f. Adjust the oscilloscope to display transients as in Figure A-3.

g. Check that the pulse width of the transients at 10 mV from the

base line is no more than 50 usec as shown.

PARD(Ripple and Noise)

Definition: Periodic and random deviation(PARD) in the unit's output

ripple and noise combine to produce a residual ac voltage superim-

posed on the dc output voltage. Constant voltage PARD is specified

as the root-mean-square(rms) or peak-to-peak(pp) output voltage in a

frequency range of 20 Hz to 20 MHz.

PARD(RMS) Measurement

Test Parameter:

Measured Variable: Output Voltage(rms)

Expected Results: Less than 200 uV rms

Test Procedure:

a. Connect the test equipment as shown in Figure A-4.

b. Turn the unit's power on and turn CURRENT control fully clock-

wise.

c. Turn up output voltage to the full rated value. Check that the

unit's CV indicator remains lighted. Reduce VOLTAGE control

if not lighted.

d. Check that the rms noise voltage at the true rms voltmeter is no

more than 200 uV.

Figure A-3. Load Transient Recovery Waveform

1 2 3 4 5 6 7 8 9 10 11 12 13 14 ... 17 18

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Agilent Technologies E3620A Service Manual Page 9

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