TM 10-3930-671-24 FIELD  CIRCUIT  TEST  (45  Amp  Systems)-  With  the  engine  not  running,  remove  the  regulator  from  the  alternator  and disconnect  leads  F1  and  F2  from  field  terminals  Fl  and  F2.    Connect  field  rheostat  and  jumper  (JU)  to  the  appropriate terminals as shown in in the applicable ground system (Figure No.  11.1).  Disconnect grounded battery cable and place test ammeter switch to a current range of approximately 0 to 10 amperes. Set control knob of field rheostat to maximum resistance position and connect as shown in Figure No.  11.1. The rheostat will protect the ammeter from damage if the field circuit is shorted. Reconnect battery ground cable and slowly reduce rheostat resistance and note the rise in the ammeter reading.  Stop test if meter indicates more than 5.0 amperes.  Altemator disassembly may be necessary to correct condition. If  entire  rheostat  resistance  can  be  eliminated  with  test  ammeter  below  5.0  amperes,  the  indicated  current  is  the  field current draw.  If the test ammeter fluctuates when the rotor is moved slightly, the brushes and slip rings require cleaning. FIGURE NO.  11.1 F-280