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Current Sampling
Resistor (Shunt)
Variable Voltage
Auto Transformer
Operation Verification Tests
The following tests assure that the power supply is per-
forming properly. They do not, however, check all the speci-
fied parameters tested in the complete performance test
described below. Proceed as follows:
a. Perform turn-on checkout procedure given in page 1-7.
b. Perform the load regulation performance tests given in
the following paragraphs.
Line Voltage Option Conversion
To convert the supply from one line voltage option to another,
the following three steps are necessary:
a. After making certain that the line cord is disconnected
from a source of power, remove the top cover from the
supply and set the two sections of the line voltage selec-
tor switch for the desired line voltage (see Figure A-2).
b. Check the rating of the installed fuse and replace it with
the correct value, if necessary. For Option OE3, use a
slow-blow 1.0-amp fuse. For standard and Option OE9,
use a slow-blow 1.6-amp fuse.
c. Mark the instrument clearly with a tag or label indicating
the correct line voltage to be used.
Figure A-2. Line Voltage Selector (set for 115 Vac)
PERFORMANCE TESTS
The following paragraphs provide test procedures for verify-
ing the power supply's compliance with the specifications of
Table 1. Proceed to the troubleshooting procedures if you
observe any out of specification performance.
Before applying power to the supply, make certain
that its line voltage selector switch (S2) is set for the
line voltage to be used. (See CAUTION notice in
operating section for additional information on S2.)
Table A-1. Test Equipment Required (Cont'd)
100 mΩ 0.1% 15 W
Range : 85-130 and 200-260
Volts
Measure output current
Vary ac input.
General Measurement Techniques
Connecting Measuring Devices. To achieve valid results
when measuring load regulation, ripple and noise, and tran-
sient response time of the supply, measuring devices must be
connected as close to the output terminals as possible. A
measurement made across the load includes the impedance
of the leads to the load. The impedance of the load leads can
easily be several orders of the magnitude greater than the
supply impedance and thus invalidate the measurement. To
avoid mutual coupling effects, each measuring device must
be connected directly to the output terminals by separate
pairs of leads.
When performance measurements are made at the front ter-
minals (Figure A-3) the load should be plugged into the front
of the terminals at (B) while the monitoring device is con-
nected to a small lead or bus wire inserted through the hole in
the neck of the binding post at (A). Connecting the measuring
device at (B) would result in a measurement that includes the
resistance of the leads between the output terminals and the
point of connection.
Figure A-3. Front Panel Terminal Connections
Selecting Load Resistors. Power supply specifications are
checked with a full load resistance connected across the sup-
ply output. The resistance and wattage of the load resistor,
therefore, must permit operation of the supply at its rated out-
put voltage and current. For example, a supply rated at 20
volts and 0.5 amperes would require a load resistance of 40 Ω
at the rated output voltage. The wattage rating of this resistor
would have to be at least 20 watts.
Electronic Load. Some of the performance test procedures
use an electronic load to test the supply quickly and accu-
rately. An electronic load is considerably easier to use than a
load resistor. It eliminates the need for connecting resistors or
rheostats in parallel to handle the power, it is much more sta-
ble than a carbon-pile load. It is easier to switch between load
conditions as required for the load regulation and load tran-
sient response tests.
A-3
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