TM 9-2350-256-20CHAPTER 6:MAINTENANCE OF ELECTRICAL SYSTEMS AND CIRCUITS6-13 REPLACE/REPAIR SWITCHING RELAY BOX ASSEMBLY (SINGLE VOLTAGEREGULATOR)-Continued3Remove cap assembly (32) from end of switching relay box (3), loosen rheostat locknut (45) with screwdriver,and turn rheostat (38) fully counterclockwise.4Connect only, the 61A leads (3) of resistor beneath switching relay box (3), leaving 61AC (46) open5Start main engine, operate at approximately 1000 rpm and charge batteries for 30 minutes, then turn offengine.6Leave main engine fuel turned off, and crank its starter for three cycles of 15 seconds on and 3 minutes off7Start APU, and warm up, unloaded for one minute8Turn on generator switch and quickly (within 15 seconds) adjust rheostat for .50 volts on meter beforemovement of rheostat no longer produces a voltage change, or voltage begins to decrease. Then turn off APUgenerator and engine.NOTEIf adjustment of rheostat cannot be made to obtain .50 volts, turn off generator and engine, returnreheostat fully counterclockwise, replace a 61A lead on resistor with 61AC lead, then continue withstep 9.9Repeat steps 6, 7, and 8 to make final adjustment of rheostat so as to obtain .50 volts on multimeter10. Tighten rheostat locknut (45), replace cap assembly (32) on switching relay box (3). Disconnect leads (2).Remove multimeter. System is calibrated.6-44.2Change 1
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