AIR TRACTOR AT-502A, Maintenance Section

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Air Tractor, Inc. Maintenance Page 55
AT-502A/502B/504 March 14, 2018
Charging System Troubleshooting Guide
GENERAL CONSIDERATIONS - As a general rule if the Starter Generator functions normally in the Start
mode there will be nothing wrong with it that would prevent it from functioning in the Generate mode.
Before attempting to correct any problem with this system first read and understand the DESCRIPTION
and THEORY OF OPERATION sections and acquaint yourself with the location and function of the various
components. Look for obvious problems such as overheating, burned wires, loose components, and loose
electrical connections. Disconnect the Cannon plug and inspect it and all other electrical connections for
corrosion. Correct any of these problems before proceeding.
EQUIPMENT
1) A multimeter capable of .01V resolution in the 0-2.5V range, .15V resolution in the 0-30V range and
capable of reading from a fraction of an OHM to several KILOHMS will be required. An autoranging digital
instrument is ideal but any good quality unit will work. For point-to-point ringout the ohmmeter function will be
used.
2) A Breakout Box - This is not absolutely essential but it is very effective in localizing many problems. It
can be fabricated per Fig. 1 or it is available from PFT Inc. at a reasonable price.