Performance Tests

Table A-1. Test Equipment Required (Cont’d)

Current Sampling	100 mΩ 0.1% 15 W	Measure output current
Resistor (Shunt)

Variable Voltage	Range : 85-130 and 200-260	Vary ac input.
Auto Transformer	Volts

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.

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-2. Line Voltage Selector (set for 115 Vac)

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.)

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