Extended Tests; Output Drift Tests - Agilent Technologies 6622A Service Manual

c. Program the current of the selected output to 1.9 amps
and the output voltage to 20.2 volts by sending the
following strings:
ISET < ch >, 1.9
VSET <ch>, 20.2
This test must be performed with a resistive load only. The
use of an electronic load will invariably inject extra ripple
and may cause the CC RMS noise to be out of specification.
d. Adjust the load resistor to about 10 ohms so that the
output voltage is close to 19 volts. Check that the CC
annunciator is on.
e. Note that the reading on the rms voltmeter should be
less than 10 mV (equivalent to 1mA RMS).
f. Repeat this test (steps a through e) for each output in
your supply.
3-28 Performance Test Record
All of the performance test specifications for the power
supply listed are in Tables 3-4 and/or 3-5. Table 3-4 covers
the 40WLV and 80WLV outputs; Table 3-5 covers the
40WHV and 80WHV outputs.

3-29 EXTENDED TESTS

These tests are similar to the Performance Tests except they
have a much longer duration and are conducted with
controlled temperature conditions.
3-30 Output Drift
The tests are divided into two parts: short term and long
term drift. For all drift tests, place the supply to be tested in
a temperature chamber or in a temperature controlled
environment such as a standards room.
3-31 Short Term Voltage Drift Test. This test measures the
change in output voltage within the first 30 minutes of a
change in the line voltage or the load.
a. Turn off the supply and connect the output to be tested
as shown in Figure 3-3 with the load switch closed and
the short switch opened. Connect the supply to the ac
power line through a variable voltage transformer and
adjust it for the nominal value.
b. Turn on the supply and select the output to be tested
(OUTPUT SELECT key on front panel).
c. Program the current of the selected output to the Low
Range Maximum Programmable Current value and the
output voltage to the Low Range Full Scale value (see
Table 3-2).
d. Adjust the load for slightly less than Low Range Full
Scale Current as read on the display. Check that the CV
annunciator is on.
NOTE
e. Adjust the transformer to 13% below the nominal line
voltage.
f. Wait 30 minutes for the output to stabilize under these
initial conditions and then record the output voltage
value.
g. Adjust the transformer to 6% above the nominal line
voltage.
h. Wait 30 minutes and record the output voltage value
again. The difference in the readings taken in steps f
and h should be less than 5.0 mV for 40WLV/80WLV
outputs and 10.4 mV for 40WHV/80WHV outputs.
i. Open the load switch and immediately record the
output voltage reading.
j. Wait 30 minutes and record the output voltage reading.
The difference in the readings taken in steps i and j
should be less than 5.0 mV for 40WLV/80WLV outputs
and 10.4 mV for 40WHV/ 80WHV outputs.
k. Repeat steps a through j for each output in your supply.
3-32 Short Term Current Drift Test. This test measures the
change in output current within the first 30 minutes of a
change in the line voltage or the load. Place the supply to be
tested in a temperature chamber or in a temperature
controlled environment such as a standards room.
a. Turn off the supply and connect the output to be tested
as shown in Figure 3-3 with the DVM connected across
the current monitoring resistor, the load switch closed,
and the short switch opened. Connect the supply to the
ac power line through a variable voltage transformer
and adjust it for the nominal value.
b. Turn on the supply and select the output to be tested
(OUTPUT SELECT key on front panel).
c. Program the current of the selected output to the Low
Range Full Scale Current value and the output voltage
to the Low Range Maximum Programmable Voltage
value (See Table 3-2).
d. Adjust the load until the output enters the CC mode
with the displayed output voltage slightly less than the
Low Range Full Scale Voltage value. The CC annuciator
must be on.
e. Adjust the transformer to 13% below the nominal line
voltage.
f. Wait 30 minutes for the output to stabilize under these
conditions and record the output current (DVM reading
X 10).
g. Adjust the transformer to 6% above the nominal line
voltage.
h. Wait 30 minutes and record the output current. The
difference in the readings taken in steps f and h should
be less than the values given below for the particular
output type being tested.
Output
40WLV
80WLV
40WHV
80WHV
3-13
Drift
9.5 mA
19 mA
6.2 mA
12.4 mA