TROUBLESHOOTINGTESTING AND ADJUSTINGPOSSIBLE CAUSESVERIFICATION PROCEDURE(Continued)resistance will be seen. As a charge from the ohmmeter is put onthe capacitor the resistance will increase to a constant reading. Setohmmeter scale to RX1000. For more information, see TESTINGPOWER RECTIFIERS AND CONTROLLED RECTIFIERS.13. Loss of Residual MagnetismCheck AC voltage at terminals (20) and (22) of regulatorassembly. Less than 4 to 5 volts at 50 hertz or 8 to 9 volts at 60hertz is an indication that residual magnetism has been lost.See FLASHING THE FIELD.14. Controlled Rectifier (CR9) HasDisconnect controlled rectifier (CR9) by removing connections ata Defectspade terminals (10, 11 and 19) of rectifier module (A2). Theohmmeter scale must be on RX1000. Check forward and reverseresistance of (CR9) by connecting the positive cable of the meterto spade terminals (11) and the negative cable to terminal (19).Read the value of resistance. Reverse the cables and read theresistance again. Typical resistance in both directions is 300.000ohms. NOTE: Controlled rectifier (CR9) is connected in parallelwith resistance-capacitance circuit in rectifier module (A2). Whenthe ohmmeter test cables are first connected to the circuit, a lowresistance will be seen. As a charge from the ohmmeter is put onthe capacitor the resistance will increase to a constant highindication.Check the continuity of the gate to cathode circuit of (CR9).Connect the positive cable of ohmmeter to spade terminal 10,and the negative cable to spade terminal (11). Typical resistance !s10 to 200 ohms.The gate circuit can be checked with the continuity tester(8S4627). Connect the positive cable to spade terminal (191 andthe negative cable to spade terminal (11). There must be no lightor meter indication. Place a separate wire connection betweenspade terminals (19) and (10). Remove the wire connection assoon as the light comes on. The light will be on until theconnection at either terminal (19) or (10) is broken. This is a testof the ability of (CR9) to "turn on." For more information, seeTESTING POWER RECTIFIERS AND CONTROLLED RECTI-FIERS.15. Rectifier Module (A2) Has aDisconnect rectifier module (A2) by removing the wires on spadeDefectterminals (6, 8, 10, 11 and 19). Check the continuity of theconnections inside of (A2) with an ohmmeter or 8S4627Continuity Tester.Check the following:FROMTOSpade Terminal (19)Heat Sink (E3)Spade Terminal (11)Cathode terminal of (CR9)Spade Terminal (10)Gate terminal of (CR9)Cathode terminal of (CR9)Heat Sink (E4)Spade Terminal (6)Anode terminal of (CR10)Spade Terminal (8)Heat Sink (E4)(Continued on next page)65
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
