HP 6268B Operating And Service Manual

5-3 TEST EQUIPMENT REQUIRED
5-4 Table 5-1 lists the test equipment required to
perform the procedures described in this section.
5-5 PERFORMANCE TEST
5-6 The following test can be used as an incoming
inspection check. Appropriate portions of the test can
be repeated either to check the operation of the instrument
after repairs or for periodic maintenance tests. The tests
are performed using a 230Vac 60Hz single-phase input
power source. If the correct result is not obtained for a
particular check, do not adjust any internal controls;
instead proceed to troubleshooting (paragraph 5-49).
5-7 CONSTANT-VOLTAGE TESTS
5-8 Connect all of the measuring devices used in
the constant voltage performance tests directly to the
power supply sensing terminals (±S). For best accuracy,
the sensing terminals must be used rather than the output
terminals, since the measuring instruments must be
connected to the same pair of terminals to which the
feedback amplifier within the power supply is connected.
This is particularly important when measuring the regula¬
tion, transient response, or ripple of the power supply.
Note that the measuring instruments should not be
connected across the load. A measurement made across
the load includes the impedance of the leads to the load
and such lead lengths can easily have an impedance several
orders of magnitude greater than the supply impedance
(typically less than 1 milliohm at dc), thus invalidating
the measurement.
5-9 To avoid mutual coupling effects, connect each
monitoring device to the sensing terminals by a separate
pair of leads. Use twisted pairs or shielded two-wire cables
to avoid pickup on the measuring leads. Connect the load
resistor across the output terminals as close to the supply
as possible. When measuring the constant-voltage perfor¬
mance specifications set the current controls well above
(at least 1 0% above) the maximum output current the
supply will draw, since the onset of constant-current
operation will cause a drop in output voltage, increased
ripple, and other performance changes not properly
ascribed to the constant-voltage operation of the supply.
5-10 Voltage Output and Voltmeter Accuracy. To
check that the supply will furnish its rated output voltage,
proceed as follows:
a. Connect load resistor (Rj_) indicated in Figure 5-1
across output terminals of supply.
b. Connect digital voltmeter across +S and —S terminals
of supply, observing correct polarity.
c. Turn CURRENT controls fully clockwise.
d. Turn on supply and adjust VOLTAGE controls until
front panel meter indicates exactly maximum rated output
voltage.
e. Digital voltmeter should indicate:
6259B, 6260B 10±0.2Vdc
6261 B 20 ±0.4Vdc
6268B, 6269B 40 ±0.8Vdc
5-11 Load Effect (Load Regulation).
Definition: The change AEQyj in the static value of
dc output voltage resulting from a change in load resistance
from open circuit to a value which yields maximum rated
output current, or vice versa.
5-12 To check the constant-voltage load effect, proceed
as follows:
a. Connect test setup shown in Figure 5-1.
b. Turn CURRENT controls fully clockwise.
c. Turn on supply and adjust VOLTAGE controls until
front panel meter indicates exactly maximum rated output
current.
d. Read and record voltage indicated on digital voltmeter.
e. Disconnect load resistor.
f. Reading on digital voltmeter should not differ from
reading recorded in step (d) by more than:
6259B, 6260B 1.2mV
6261B 2.2mV
6268B, 6269B 4.2mV
Figure 5-1. Constant-Voltage Load Regulation Test Setup
5-2

HP 6268B Specifications

General

Brand	HP
Model	6268B
Category	Power Supply
Language	English