Generac Power Systems 55, 75, 65 manual Short to Ground, Battery Charge Rectifier

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Section 7

DIAGNOSTIC TESTS

Short to Ground:

4.Set the VOM to measure resistance. Connect the positive (+) test lead to the case housing of the BCR. Connect the negative (-) test lead to an outer terminal. “Infinity” should be measured. Now connect the negative test lead to the BCR center terminal. “Infinity” should be measured. Next, connect the negative test lead to the remaining outer BCR terminal. Once again “Infinity” should be measured.

Figure 7-10. – Battery Charge Rectifier

RESULTS:

1.If any of the previous steps has failed, replace the Battery Charge Rectifier.

2.If the BCR tests good, go to Test 17.

TEST 17 - CHECK BATTERY CHARGE

WINDINGS / BATTERY CHARGE RESISTOR

DISCUSSION:

The Battery Charge Winding (BCW) produces AC voltage that is delivered to the Battery Charge Rectifier. The Battery Charge Winding is a center tapped winding consisting of the following Stator Leads: Wire 66, Wire 77 and Wire 55. The Battery Charge Resistor is used as a current limiting resistor.

PROCEDURE:

1.Disconnect the Stator Leads (Wire 66 and Wire 77) from the Battery Charge Rectifier. (Be sure to disconnect Stator Lead Wire 66 “Black” from Wire 66 “Blue” connector for this test). Disconnect the Stator Lead Wire 55 from the Battery Charge Resistor.

2.Set the VOM to measure resistance at the “R x 1” scale. Connect one test lead to Stator Lead Wire 66. Connect the other test lead to Stator Lead Wire 55. Normal Battery Charge Winding resistance should be measured.

3.Connect one test lead to Stator Lead Wire 77. Connect the

other test lead to Stator Lead Wire 55. Normal Battery Charge Winding resistance should be measured.

4.Connect one test lead to Stator Lead Wire 55. Connect the other test lead to Stator Leads Wire 11 & 33 at the back of CB1. “Infinity” should be measured.

5.Connect one test lead to Stator Lead Wire 55. Disconnect Stator Lead Wire 2 from the DPE circuit breaker (CB3) and connect the other test lead to Wire 2. “Infinity” should be mea- sured.

6Connect one test lead to Stator Lead Wire 55. Connect the other test lead to frame ground. “Infinity” should be measured.

7.Connect one test lead to the Battery Charge Resistor terminal that Wire 55 was removed from. Connect the other test lead to frame ground. One (1) ohm should be measured. If 1 ohm was not measured, remove Wire 0 from the Battery Charge Resistor. Connect one test lead to Wire 0 and the other test lead to frame ground. “Continuity” should be measured. Repair or replace Wire 0 if defective and retest the Battery Charge Resistor.

BATTERY CHARGE WINDING RESISTANCE *

QP55 (Model 4702/4703)

ACROSS WIRES:

OHMS

 

55 & 66

0.100Ω − 0.116Ω

 

55 & 77

0.100Ω − 0.116Ω

 

BATTERY CHARGE WINDING RESISTANCE *

QP65 (Model 4704/4705)

ACROSS WIRES:

OHMS

 

55 & 66

0.104Ω − 0.120Ω

 

55 & 77

0.087Ω − 0.101Ω

 

BATTERY CHARGE WINDING RESISTANCE *

QP75 (Model 4706/4707)

ACROSS WIRES:

OHMS

 

55 & 66

0.092Ω − 0.107Ω

 

55 & 77

0.076Ω − 0 . 0 8 8 Ω

 

*Resistance values In ohms at 20° C. (68° F.). Actual readings may vary depending on ambient temperature. A tolerance of plus or minus 5% is allowed.

RESULTS:

1.For Steps 2 & 3, keep in mind that the resistance values are very low. Depending upon the quality of the VOM, it may read “Continuity” across these windings. Exercise good judgement with these values.

2.If Steps 2, 3, 4, 5 & 6 fail any test, replace the Stator.

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Contents Diagnostic Repair Manual Safety Replacement PartsTable of Contents Section Specifications & Charts Section Exploded Views / Part NumbersMagnetism Electromagnetic FieldsElectromagnetic Induction Simple AC Generator More Sophisticated AC GeneratorGenerator Operating Diagram Field Boost Generator AC Connection SystemLine Breakers 120 Volts only Connection for 120 Volts Only Reconnection for Dual Voltage OutputRotor Assembly Stator AssemblyBattery Charge Components Brush HolderExcitation Circuit Components GeneralAdjustment Procedure Crankcase BreatherVoltage Regulator DescriptionInstall Breather Install oil vapor collector and retainerControl Panel Component Identification Check BreatherCleaning the Generator Effects of Dirt and MoistureInsulation Resistance Testers Drying the GeneratorBrushing and Vacuum Cleaning Stator Insulation ResistanceCloth or Compressed AIR Stator SHORT-TO-GROUND TestsTesting Rotor Insulation Testing Stator InsulationTesting Rotor Insulation MegohmmeterMeters VOMMeasuring AC Voltage Measuring DC VoltageMeasuring AC Frequency Measuring CurrentMeasuring Resistance Electrical Units Ohms LAWAmpere VoltIntroduction Operational AnalysisCircuit CONDITION- Rest Circuit CONDITION- Priming Circuit CONDITION- Cranking Circuit CONDITION-RUNNING Choke Heater CHCircuit CONDITION- Shutdown Circuit CONDITION- Fault Shutdown Sure Switch LOPBattery Recommended BatteryBattery Cables Engine Controller Circuit BoardFuel Primer Switch START-STOP SwitchAMP Fuse Starter Contactor Relay Starter Motor Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Procedure Test 1- Check NO-LOAD Voltage FrequencyTest 2- Check Engine Governor DiscussionGovernor Adjustment Test 3- Test Excitation Circuit BreakerTest 4- Fixed Excitation TEST/ROTOR AMP Draw If continuity was indicated, go to TestTest 5- Wire Continuity Re-connect Wire 11 and Wire 22 to the Voltage RegulatorSet the VOM to measure AC voltage Set a VOM to its Rx1 scaleTest 6- Check Field Boost Test 7 Test Stator DPE WindingIf field boost checks good, replace the Voltage Regulator Test 8- Check Sensing Leads / Power Windings Across Wires Ohms11S 22S Model OhmsTest 9- Check Brush Leads Test 10 Check Brushes & Slip RingsTest 11- Check Rotor Assembly Tance Tests ProcedureTest 12 Check Main Circuit Breaker Replace the Rotor if it fails the testTest 15 Check Battery Charge Output Test 16 Check Battery Charge RectifierBattery Charge Rectifier BCR is a full wave rectifier Test 13- Check Load Voltage Frequency10. Battery Charge Rectifier Short to GroundTest 19- Test Primer Switch Set a VOM to read battery voltage 12 VDCAlso see Fuel Primer Switch, Test 18 TRY Cranking the EngineTest 20- Check Fuel Pump 13. The LPG Fuel Solenoid FSTest 22- Check Battery & Cables Test 23- Check Power Supply to Circuit BoardTest 21- Check 7.5 AMP Fuse Test 24 Check START-STOP Switch 17. Start-Stop SwitchTest 26- Check Starter Contactor Relay Set a VOM to measure DC voltage 12 VDCTest 26A Check Starter Contactor Test 27 Check Starter MotorConditions Affecting Starter Motor Performance Checking the Pinion Tools for Starter Performance TestMeasuring Current TachometerTesting Starter Motor Test 28- Check Fuel SupplyTest Bracket Remove Starter Motor28 LP Gas Carburetion Diagram Discussion LPG ModelsTest 29 Check Wire 14 Power Supply Test 30 Check WireBattery voltage is not measured, proceed to Step Crank the engine. The meter should indicate battery voltageTest 31 Check Fuel Solenoid Gasoline Models Test 32 Check Ignition SparkCylinder Balance Test Conclusion No cylinder is weakest of the two cylindersTest 34 Check and Adjust Ignition Magnetos Test 33 Check Spark Plugs37. Setting Ignition Magneto Armature Air Gap Test 35 Check Valve Adjustment Adjusting Valve ClearanceChecking Flywheel Magnet Flywheel KEYInstall Rocker ARM Cover Test 36 Check CarburetionTest 37 Check Choke Solenoid 43. Connector Adjust the regulated pressure on the gauge to 80 psi Down Test / Compression TestRepeat Steps 1 through 8 on remaining cylinder Check CompressionTest 39 Check OIL Pressure Switch Test 40 Test OIL Temperature SwitchIf all steps check GOOD, go to Test Test 41 Test Choke Heater Test 42 Check LPG Fuel SolenoidShort to Ground 49. Fuel Solenoid Major Disassembly ENCLOSURE/PANEL RemovalStator Removal Rotor RemovalBelt Tensioning Engine RemovalStarter Removal FLYWHEEL/MAGNETO Removal Page Section Exploded Views / Part Numbers Part NO. QTY Description Enclosure Drawing No E1011-B QTY Description Sheet Metal Drawing No E1012-E QTY Description Flywheel Assy GT-990Control Panel Drawing No E1013-A Wire ASM GRD STD Conn Switch Spdt ON-MOM-ONSwitch 6A Spdt Not Shown PANEL, TOP ControlTwin Engine Drawing No E1014-B ASSEMBLY, Crankcase RV ASSEMBLY, BreatherASSEMBLY, Head #1 ASSEMBLY, OIL Fill CAPLP Regulator Drawing No E1530 CASTING, Twin Regulator Housing Washer Flat M4SOLENOID, Twin Regulator SPRING-SOLENOID PlungerSpecifications & Charts Generator Specifications Nominal Resistances of Generator Windings AT 68FEngine Speeds and Voltage Specifications Page Electrical Data Electrical Data PO BOX 297 WHITEWATER, WI

65, 75, 55 specifications

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