Guardian Technologies Understanding DPE Winding Diagnostic Tests for Portable Generators
Page 42

Section 7

DIAGNOSTIC TESTS

3.Set the Start-Stop Switch to “START.” During cranking only, measure DC voltage. It should read 3-5 VDC. Reconnect Wire 4 to the Voltage Regulator. If voltage is measured, it can be assumed that the Field Boost is working. Stop testing. If volt- age is not measured, proceed to Step 4.

4.Test D2 diode: Place a VOM to measure continuity. Place one test lead on one end of the diode and the other test lead on the other end. Check for continuity, then reverse the leads and retest. Continuity should only be measured in one direction, and when it is measured, it should have a single beep and not a constant tone. If continuity is measured in both directions then the diode will need to be replaced. If diode tests good, proceed to Step 5.

5.Test R2 resistor: Place a VOM to measure resistance. Disconnect wires going to the terminals of the resistor. Place the test leads on each terminal of the resistor. Resistance should be 20 Ohms. If resistance is bad, replace the resistor. If resistor is good, proceed to Step 6.

6.Test Wire 14: Place a VOM to measure continuity. Disconnect Wire 14 from the R2 resistor. Unplug the BH2 connector. Place one test lead on the Wire 14 end that was previously on the resistor. Place the other test lead on Pin 7 of the BH2 con- nector. Continuity should be measured. If wire is open, replace it. If wire is good, disconnect Wire 14 from the circuit board located on Terminal 11. Place one test lead on this end and the other test lead on the other BH2 connector Pin 7. Continuity should be measured. If continuity is not measured, replace the wire. If continuity is measured, make sure that the connection on BH2 is good. If the connection appears to be good, then replace the circuit board.

RESULTS:

1.If field boost voltage checks good in step 3, than replace the voltage regulator.

2.If field boost is not measured, replace failed parts in Steps 4-6.

TEST 7 - TEST STATOR DPE WINDING

DISCUSSION:

An open circuit in the Stator excitation windings will result in a loss of unregulated excitation current to the Voltage Regulator. The flow of regulated excitation current to the Rotor will then terminate and the unit's AC output voltage will drop to a value that is equal to the rotor’s residual magnetism (about 5 - 12 VAC).

PROCEDURE:

1.Disconnect Wire 2 from the Excitation Circuit Breaker.

2.Disconnect Wire 6 from the Voltage Regulator.

3.Set a VOM to its “Rx1” scale and zero the meter.

2

6

2

6

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A. Schematic

B. Pictorial

Figure 7-4. – Stator Excitation Winding

4.Connect the VOM test leads across the terminal ends of Wires 2 and 6. The VOM should indicate the resistance of the Stator Excitation (DPE) Windings.

EXCITATION “DPE” WINDING RESISTANCE *

(Measured Across Wires 2 & 6)

MODEL QP75D

1.24 OHMS

*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.

5.Now, set the meter to its “Rx1 K” or “Rx10,000” scale and zero the meter. Test for a “short-to-ground” condition as follows:

a.Connect one meter test lead to Stator lead No. 2, the other test lead to a clean frame ground.

b.The meter should read “Infinity”. Any other read- ing indicates a “short-to-ground” condition and the Stator should be replaced.

6.Test for a short between windings as follows:

a.Meter should be set to its “Rx1 K” or “Rx10,000” scale.

b.Connect one meter test lead to Stator Wire 2, the other test lead to Stator lead No. 11. The meter should read “Infinity”.

c.Connect one VOM test lead to Stator lead No. 2 the other test lead to Stator lead No. 33. “Infinity” should be indicated.

d.Connect one VOM test lead to Stator lead No. 2 and connect the other test lead to Stator lead No. 66. “Infinity” should be indicated.

RESULTS:

1.If the Stator excitation (DPE) windings are open or shorted, replace the Stator assembly.

2.If the excitation windings are good, perform “Insulation Resistance Test”, page 13.

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Contents Diagnostic Repair Manual Safety Replacement PartsTable of Contents 57-59 Magnetism Electromagnetic FieldsElectromagnetic Induction Simple AC Generator More Sophisticated AC GeneratorGenerator Operating Diagram Field Boost Generator AC Connection SystemLine Breakers 120 VAC only Connection for 120/240 VAC Dual Voltage Rotor Assembly LIC Grit or Abrasive to Clean Slip RingsExcitation Circuit Components Battery Charge ComponentsBrush Holder General162 Adjust POT LEDAdjustment Procedure Voltage RegulatorControl Panel Component Identification Control Panel ComponentsDrying the Generator Cleaning the GeneratorEffects of Dirt and Moisture Insulation Resistance TestersCloth or Compressed AIR Brushing and Vacuum CleaningStator Insulation Resistance Stator SHORT-TO-GROUND TestsTesting Rotor Insulation MegohmmeterMeasuring AC Voltage MetersVOM Measuring DC VoltageMeasuring AC Frequency Measuring CurrentMeasuring Resistance Electrical Units Ohms LAWIntroduction Operational AnalysisCircuit CONDITION- OFF Circuit CONDITION- PRE-HEAT Circuit CONDITION- Cranking Circuit CONDITION-RUNNING Circuit CONDITION- Shutdown Circuit CONDITION- Fault Shutdowns Battery Engine Control Circuit BoardCharging a Battery Effects of TemperatureChecking Battery State of Charge Adding WaterAMP Fuse Preheat SwitchSTART/STOP Switch Starter Contactor & MotorFuel NOZZLES/INJECTORS Engine GovernorFuel Injection Pump Glow PlugsEngine Protective Devices LOW OIL Pressure Switch High Coolant Temperature SwitchAdapter LOW OIL Pressure Switch Overspeed ProtectionTroubleshooting Flowcharts Troubleshooting Flowcharts Problem 3 No Battery Charge Output Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Test 2 Check & Adjust Test 1- Check NO-LOAD Voltage FrequencyTest 3- Test Excitation Circuit Breaker Test 4- Fixed Excitation TEST/ROTOR AMP DrawTest 6- Check Field Boost Test 5- Wire ContinuityRe-connect Wire 11 and Wire 22 to the Voltage Regulator Set a VOM to its Rx1 scaleTest 7 Test Stator DPE Winding Model QP75D159W Test 8- Check Sensing Leads / Power WindingsTest 9- Check Brush Leads 184WTest 11- Check Rotor Assembly Tance Tests ProcedureTest 10 Check Brushes & Slip Rings Test 13- Check Load Voltage Frequency Test 15 Check Battery Charge OutputTest 12 Check Main Circuit Breaker Test 14- Check Load Watts & AmperageTest 16 Check Battery Charge Rectifier Battery Charge Rectifier BCR is a full wave rectifierShort to Ground Test 18 TRY Cranking the Engine Test 19- Test PRE-HEAT SwitchSet a VOM to read battery voltage 12 VDC Test 20- Check Fuel PumpDisconnect the connector from the wires of the fuel pump Test 22- Check Battery & CablesTest 23- Check Power Supply to Circuit Board Test 21- Check 14 AMP FuseTest 24 Check START-STOP Switch Not ActivatedTest 26- Test Starter Contactor Test 27 Check Starter MotorConditions Affecting Starter Motor Performance Tools for Starter Performance Test Checking the PinionPinion Measuring CurrentTest Bracket Testing Starter MotorTachometer Starter motor test bracket may be made as shown in FigureIf Wire 18 checks GOOD, proceed to Problem 8 Section Test 29 Check Wire 14 Power SupplyTest 30 Check Wire Test 28- Check Fuel SupplyTest 32- Test Preheat Contactor Test 33- Test Glow PlugsTest 34- Test D1 Diode Test 35- Check Valve Adjustment Remove the valve cover from engine Disconnect the batteryTest 36- Fuel Injector Pump Down Test / Compression Test If fuel is noted, proceed to next step in flowchartAdjust the regulated pressure on the gauge to 80 psi Repeat Steps 1 through 8 on remaining cylinderTest 38 Check OIL Pressure Switch Test 40- Test Water Temperature SwitchTest 39- Check Circuit Board for Ground Test 43 Check Wire 15 for Short to Ground If continuity is measure, replace the switchComponents for Short to Ground Major Disassembly RE-ASSEMBLY Belt TensioningLine Corner UP Between 5˚ to 10˚ FAN BeltSection Exploded Views / Part Numbers Flywheel Assembly Rotor AssemblyStator Assembly Bearing Carrier, FrontBase Frame Drawing No D2357-A Base Frame Weldment Door, Service RearDoor, Service Front Slide Latch FlushEnclosure Drawing No D2358-D Gasket, Electrical Access Cover, Access LiftCover, Access Electrical Decal, Battery +Views / Part Cover Plate, Scroll Weldment 25 26 Rectifier, Battery Charging Assembly, Potted RegulatorAssembly Marine Control Board Wire Assembly #Intake and Exhaust System Drawing No D2362-B Air Filter Exhaust GasketChamber Air Intake Hose, Air InletViews / Part Numbers Cable, Battery Fuel Pump AssemblyBoot, Battery Cable Wire Assembly, Black #4 GroundCustomer Controls Assembly Drawing No D2364-D Boot / Nut / Preheat Switch Start / Stop SwitchSwitch, Pushbutton Spst Boot, Circuit BreakerKEY Camshaft AssemblyCamshaft Gear Gear2630 Liter Diesel Cylinder Head Drawing No D2794 Liter Diesel Crankshaft, Piston and Flywheel Drawing No -B Thrust Washer Idler Gear AssemblySpring OIL Pump CoverIntake Rocker ARM Rocker ARM AssemblyIncludes ALL Components Shown below Exhaust Rocker ARMLiter Diesel Injector Pump Drawing No -C Tank Return Model 04270 To Injection Pump To Fuel Pump 27 25 19 18 HOUSING, Timing Gear 3114 Liter Diesel Water Pump Drawing No Charts Engine Specifications Generator SpecificationsROTOR/STATOR Resistance Values Type Quietpact ModelPage Data Data Electrical Data Schematic Drawing No C4945-A Model C4945Electrical C4946-ASheet 2 OF4996 REV. O
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