8 Service and MaintenanceConstant Voltage (CV) Verifications198 E364xA User’s and Service Guide10 Record the value displayed on the controller. This valueshould be within the limit of (DVM ±15 mV)[1] or(DVM ±35 mV)[2] for output1, or (DVM ±45 mV)[1] or(DVM ± 85 mV)[2] for output2.11 Repeat step 1 through step 10 for the other output.CV load effect (load regulation)This test measures the immediate change in the outputvoltage resulting from a change in the output current fromfull to no load.1 Turn off the power supply and connect a digital voltmeterbetween the (+) and (–) terminals of the output as shownin Figure 8- 2.2 Turn on the power supply. Select the output to be testedand the high voltage range (20 V/1.5 A)[3], enable theoutput, and set the display to the limit mode. When thedisplay is in the limit mode, program the output currentto the maximum programmable value and the voltage tothe full rated value (20.0 V)[3].3 Operate the electronic load in constant current mode andset its current to be the same as the power supply fullrated value (1.5 A)[3]. Check that the front panel CVannunciator remains lit. If not lit, adjust the load so thatthe output current drops slightly until the CV annunciatorlights up. Record the output voltage reading on the digitalvoltmeter.4 Operate the electronic load in open mode (input off).Record the output voltage reading on the digital voltmeterimmediately. The difference between the digital voltmeterreadings in step 3 and step 4 is the CV load regulation.The difference of the readings during the immediatechange should be within the limit of (5 mV)[1] or(9 mV)[2].[1] For the E3646A/E3648A model.[2] For the E3647A/E3649A model.[3] For the E3646A model. For other models, refer to Table 8-5.
