Generac Power Systems 5413 Section DIAGNOSTIC TESTS, Test 1 - Check No-Load Voltage and Frequency

Section 7

DIAGNOSTIC TESTS

Introduction

The “Diagnostic Tests” in this chapter may be per- formed in conjunction with the “Flow Charts” of Section 6. Test numbers in this chapter correspond to the numbered tests in the “Flow Charts”.

Tests 1 through 13 are procedures involving problems with the generator’s AC output voltage and frequency (Problems 1 through 3 in the “Flow Charts”).

Tests 14 through 41 are procedures involving prob- lems with engine operation (Problems 3 through 10 in the “Troubleshooting Flow Charts”).

You may wish to read Section 4, “Measuring Electricity”.

NOTE: Test procedures in this Manual are not nec- essarily the only acceptable methods for diagnos- ing the condition of components and circuits. All possible methods that might be used for system diagnosis have not been evaluated. If you use any diagnostic method other than the method presented in this Manual, you must ensure that neither your safety nor the product’s safety will be endangered by the procedure or method you have selected.

Test 1 – Check No-Load Voltage and

Frequency

DISCUSSION:

The first step in analyzing any problem with the AC generator is to determine the unit’s AC output volt- age and frequency. Once that has been done, you will know how to proceed with specific diagnostic tests.

PROCEDURE:

3.If AC output voltage and frequency are both “zero”, go to Test 11.

4.If the no-load voltage and frequency are within the stated limits, go to Test 12.

NOTE: The term “low voltage” refers to any voltage reading that is lower than the unit’s rated voltage. The term “residual voltage” refers to the output voltage supplied as a result of Rotor residual magnetism (approximately 5-12 VAC).

Test 2 – Check Stepper Motor Control

*Caution! Do not stand in front of carburetor when checking the stepper motor movement due to possible backfire from the carburetor.

PROCEDURE:

1.Remove air cleaner cover to access stepper motor.

2.Physically grab the throttle and verify the stepper motor, linkage and throttle do not bind in any way. If any binding is felt, repair or replace components as needed. Some resistance should be felt as the stepper motor moves through it’s travel.

3.Physically move the throttle to the closed position by pulling the stepper motor arm towards the idle stop.

a.Press the Start-Stop switch (SW1) to “START” and watch for stepper motor movement. It should move to the wide open (down) position during cranking. Once the unit starts the stepper motor should move the throttle to a position to maintain 60.0-60.5 Hertz.

1.Set a volt-ohm-milliammeter (VOM) to read AC voltage. Connect the meter test leads across cus- tomer connection leads T1 (Red) and T2 (White).

2.Disconnect or turn OFF all electrical loads. Initial checks and adjustments are accomplished at no- load.

3.Start the engine, let it stabilize and warm up.

4.Read the AC voltage.

5.Connect an AC frequency meter across AC output leads T1 (Red) and T2 (White). Repeat the above procedure.

RESULTS:

For units rated 60 Hertz, no-load voltage and fre- quency should be approximately 122-126 VAC and 60.0-60.5 Hertz respectively.

1.If AC voltage and frequency are BOTH corre- spondingly high or low, go to Test 2.

2.If AC frequency is good but low or residual volt- age is indicated, go to Test 4.

IDLE
STOP	THROTTLE
	ARM
UP	DOWN
CLOSED
	OPEN
THROTTLE
LINKAGE
STEPPER
MOTOR

Figure 7-1. Throttle Position

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