Guardian 4721, Repair Manual

Page: 23 / 115

Page 19
PART TITLE PAGE
2.1 Description and Major Components 20
2.2 AC Output Operational Analysis 24
2.3 AC Output Troubleshooting Flow Charts 26
Problem 1 - Generator Produces ZeroVoltage or
ResidualVoltage 26
Problem 2 - Generator Produces
LowVoltage at No-Load 28
Problem 3 - Generator Produces High
Voltage at No-Load 28
Problem 4 -Voltage and Frequency Drop
ExcessivelyWhen Loads Are Applied 29
2.4 AC Output Diagnostic Tests 30
TABLE OF CONTENTS
1.5 LITER PREPACKAGED
HOME STANDBY
GENERATORS
PART 2
PREPACKAGED
LIQUID-COOLED
AC GENERATORS
TEST DESCRIPTION ......................................PAGE
1 Check Main Circuit Breaker ................................ 30
2 Check AC Output Voltage .................................. 31
3 Test Excitation Circuit Breaker .......................... 31
4 Test Thermal Protector ...................................... 32
5 Fixed Excitation Test/Rotor
Amp Draw Test .................................................. 32
6 Wire Continuity .................................................. 33
7 Check Field Boost .............................................. 33
8 Testing the Ststor with a VOM ............................ 34
9 Resistance Check of Rotor Circuit .................... 35
TEST DESCRIPTION ......................................PAGE
10 Check Brushes
and Slip Rings .................................................... 35
11 Test Rotor Assembly .......................................... 35
12 Check AC Output Frequency ............................ 36
13 Check and Adjust Governor Board
and Stepper Motor .............................................. 36
14 Check and Adjust
Voltage Regulator .............................................. 38
15 Check Voltage and Frequency Under Load ...... 38
16 Check for Overload Condition ............................ 38
17 Check Engine Condition .................................... 38