COVER 5218768 - Caterpillar

Introduction
Check for loose or corroded terminals. Make sure wire connections are correct. Check the accuracy of the voltmeter and frequency meter/tachometer.To reduce troubleshooting time, simplify the system or circuit by eliminating non-essential components. If, at this point, it is determined that the basic system is functioning, the circuits or components can be added back in, one at a time until the problem is located.If elimination of non-essential components does not correct the problem, the troubleshooting procedure will check components in the basic system. If all other basic components (i.e. rotating field assembly, exciter stator etc.) are operating correctly, then replace the VR4 regulator. As a last step after confirming correct operation under no load conditions, operate the generator under a load.The VR4 regulator will be serviced as a complete unit. Its fuse is the only replaceable part. VR4 regulators must be checked through the bench test before making a claim on warranty (see Bench Test).Problem List
Problem 1 - No AC Voltage.Problem 2 - Low AC Voltage.Problem 3 - High AC Voltage.Problem 4 - Unstable AC Voltage.Problem 1 - No AC Voltage
Procedure A - Check AC voltage at regulator between terminals 20 and 22.* If above 200 volts: Check meters.* If 0 volts: Flash the field. See SR4 Generator Service Manual, SENR3985.* If 0 to 15 volts: Go to Procedure B. Procedure B - Isolate RegulatorDisconnect leads from regulator terminals F1 and F2. Connect a 12 volt automotive type battery across exciter leads F1 (+) and F2 (-). Operate generator at half of the rated speed.