TM 5-6115-590-12 air  and  wipe  wires  with  a  clean  rag  moistened  with  an approved cleaning solvent. (b) Visually inspect harness for damaged   or   corroded   connectors,   frayed   or   burned insulation and evidence of other damage. (3) Test.  Test individual wires for continuity. (4) Installation.    Install  replacement  harness assembly in reverse order of removal. c. Battery Charger (fig. 4-38). (1) Removal.    Tag  and  disconnect  electrical harness    connector    plug    from    the    battery    charger. Remove  four  screws,  four  flat  washers  and  four  lock washers.  Remove battery charger. (2) Cleaning and Inspection. (a) Clean     battery     charger     with     dry filtered compressed air or a clean rag lightly moistened with an approved cleaning solvent. (b) Visually  inspect  battery  charger  for corrosion, cracks, damaged threads, excessive heat, or other evidence of damage. (3) Test.  Disconnect leads from the positive and   negative   terminals   on   the   battery   charger   and connect   a   multimeter   to   the   positive   and   negative terminals   of   the   charger.      Start   the   power   unit   as described  in  paragraph  2-10  and  observe  the  voltage output on the multimeter.  Vary the output of the charger by  turning  the  adjustment  screw.    Turn  the  adjusting screw   clockwise   to   increase   the   voltage   output   and counterclockwise to decrease the voltage output. CAUTION Do  not  exceed  an  output  of  30  volts.    If the   output   voltage   can   be   read   on   the multimeter     and     the     voltage     can     be adjusted   between   24   and   30   volts,   the charger is operating satisfactorily. (4) Adjustment.  With the leads disconnected from    the    positive    and    negative    terminals    and    a multimeter connected, turn the voltage adjust screw until the    voltage    output    is    28    volts.        Disconnect    the multimeter  and  reconnect  the  leads  to  the  positive  and negative terminals of the battery charger. (5) Installation.        Install    battery    charger    in reverse order of removal. d. Voltage Regulator VR-2 60 Hz. (1) Removal. (a) Tag  and  disconnect  wiring  harness connector from voltage regulator (fig. 4-37). (b) Remove attaching screws, nuts and washers    and    remove    regulator    from    support    frame below upper electrical power chassis. (2) Cleaning and Inspection. (a) Clean voltage regulator with filtered compressed air or wipe with clean rag moistened with an approved    cleaning    solvent.        Clean    receptacle    with filtered compressed air or an electrician's brush. (b) Visually inspect regulator for corrosion, cracks, damaged threads or other evidence of damage. (3) Test.  The following test may be used to isolate  a  faulty  voltage  regulator  by  substituting  for  the regulator  function.    If  60  Hz  voltage  is  incorrect  or  not available, perform test as follows. (a) Start the power unit as described in paragraph 2-10, and operate the 60 Hz electrical system as described in paragraph 2-12a. (b) With   the   60   Hz   electrical   system operating,  disconnect  plug  P32  from  voltage  regulator VR-2.        Using    an    adjustable    5,000    ohm,    10    watt potentiometer, apply 24V DC through a 25 ohm, 50 watt resistor into pins J and E on plug P32. (c) Adjust   potentiometer   until   voltage begins  to  increase  on  panel  60  Hz  AC  voltmeter  and increase voltage to 120V AC line-to-neutral. NOTE If  load  contactor  trip  indicator  illuminates due to under-voltage, reset load contactor switch and increase voltage to 120V AC. (d) If  120  volts  are  obtainable  and  the load contactor does not trip, the 60 Hz generator output is  correct  and  the  voltage  regulator  has  failed.    If  120 volts  are  not  obtainable,  the  generator  or  other  60  Hz components are defective.  Refer to paragraph 4-61 for 60 Hz generator maintenance instructions. (4) Installation.      Install   voltage   regulator   in reverse order of removal. e. Voltage Regulator VR1 400 Hz. (1) Removal (fig. 4-37). (a) Tag  and  disconnect  wiring  harness connector from voltage regulator. (b) Remove attaching screws and washers    and    remove    voltage    regulator    from    upper electrical power chassis. (2) Cleaning and Inspection. (a) Clear. voltage regulator with filtered    compressed    air    or    wipe    with    a    clean    rag moistened  with  an  approved  cleaning  solvent.    Clean receptacle with filtered compressed air or an electrician's brush. (b) Visually inspect regulator for corrosion, cracks, damaged threads or other evidence of damage. (3) Testing.    The  following  test  may  be  used to  isolate  a  faulty  voltage  regulator  by  substituting  for the regulator function.  If 400 Hz voltage is incorrect or not obtainable, perform the test as follows. (a) Start the power unit as described in paragraph   2-10,   and   operate   the   400   Hz   electrical system as described in paragraph 2-12b. (b) With  the  400  Hz  electrical  system operating,  disconnect  plug  P30  from  voltage  regulator VR1.        Using    an    adjustable    5,000    ohm,    10    watt potentiometer, apply 24V DC through a 25 ohm, 50 watt resistor to pins J and E on plug P30. 4-86