Radio Suppression Capacitor Open or Short Test

NOTE: This is an open or short circuit test only and does not measure capacitance value. Actual capacitance value should be measured on a capacitance bridge at 1 kHz at a maximum voltage of 350 mV rms.

The radio noise suppression capacitor is built into the rectifier assembly and cannot be serviced by itself. To test the capacitor, place the ohmmeter, Rotunda or equivalent, Multiply-By setting at 1000 and zero the meter.

NOTE: Text values shown in brackets [ ]___ are referenced to Rotunda Model 059-00010 and may be different if another tester is used.

CAUTION: Digital meters cannot be used to perform this capacitor test. The rectifier assembly must be dry.

1. Contact one probe to the rectifier assembly B+ terminal and contact the other probe to the rectifier assembly ground. REVERSE the probes and repeat the test. One position should give an infinite reading, indicating the reverse current direction through the diodes, and the other position should give a reading of about [1000] ____ohms, indicating the forward current direction. The SAME reading in both directions indicates an inoperative rectifier assembly.
2. To check the capacitor, contact the probes to the rectifier assembly B+ terminal and ground in the FORWARD current [1000] ____ ohms reading direction. While observing the meter indicator needle, REVERSE the probes and again contact them to the rectifier assembly B+ terminal and ground. The indicator needle should jump slightly (indicating that the ohmmeter batteries are charging the capacitor) and then return to its original position (infinite reading). If the needle does NOT jump, the capacitor is OPEN. Replace the rectifier assembly.