TM  5-6115-323-14 Section  Il.  TROUBLESHOOTING 5-3.    General This section contains troubleshooting or malfunc- tion information and tests for locating and correcting most of the troubles which may develop in the genera- tor sets. Each malfunction or trouble symptom for an individual component, unit, or system is followed by a list of test or inspections necessary for you to deter- mine probable causes and suggested corrective actions for you to remedy the malfunction. 5-4. Troubleshooting a. This manual cannot list all possible malfunc- tions that may occur or all tests or inspections, and corrective  actions.  If  a  malfunction  is  not  listed (except when malfunction and cause are obvious), or is not corrected by listed corrective actions, you should notify  higher  level  maintenance. b. Table  5-2  lists  the  common  malfunctions  that you may find during the operation or maintenance of the generator sets or their components. You should perform  the  tests/inspections  and  corrective  actions  in the  order  listed. NOTE Before you use this table, be sure you have performed  all  normal  operational  checks.  If you have a malfunction which is not listed in this table, notify the next higher level of maintenance. Air force users may perform maintenance within the scope of their capa- bilities. Table  5-2.  TROUBLESHOOTING MALFUNCTION TEST OR INSPECTION CORRECTIVE  ACTION 1. 2. ENGINE FAILS TO START OR MALFUNC- TIONS Inspect    the  engine  for  an  electrical  or  mechanical failure. Refer to the appropriate service manual (See Appendix A). GENERATOR  FAILS TO BUILD UP RATED VOLTAGE Step  1.  Manually  flash  the  field  as  follows: (1)  Connect  two  1.5  volt  flashlight batteries in series and connect a wire to each end. (2) Connect the positive wire from the batteries to terminal No. 5 on the voltage  regulator. (3) Start the generator set. Table 5-2.  TROUBLESHOOTING  -  Continued MALFUNCTION TEST OR INSPECTION CORRECTIVE  ACTION 2. GENERATOR FAILS TO BUILD UP RATED VOLTAGE-Continued Step  2. (4)  Momentarily  touch  the  negative wire  to  terminal  No.  6  on  the  voltage regulator to flash the field. If the field cannot be flashed, proceed to Step  2. Inspect the voltage regulator for cracks, signs  of  overheating  and  other  damage. Test  the  voltage  regulator  as  follows: (1) Voltage Regulator (AC Unit). (a) Select desired voltage setting on  the  voltage  changeover  switch  (  120  V or  240  V)  and  start  the  generator  set. Load cables should not be attached to the  output  terminals. (b) Using a multimeter, check voltage  across  output  terminals  to  verify reading on set voltmeter. If the votage is low and adjustment of the variable resis- tor  will  not  correct  the  deficiency,  check the exciter voltage across terminals 5 or 6 of the voltage regulator. This voltage will vary, but should be about 25 volts DC. If no voltage appears on the regula- tor  terminals,  the  voltage  regulator  is defective and should be replaced. (c)  If  voltage  across  regulator  ter- minals 5 and 6 is satisfactory, stop the generator set, attach the load cables, and restart  the  set. (2) Voltage Regulator (DC Unit). (a)  Disconnect  load  cables  and start  generator  set. (b)  Trip  the  circuit  breaker  to “ON” position, and observe reading on set  voltmeter. (c)  Using  a  multimeter,  check  the voltage  across  the  output  terminals  to verify the reading on the set voltmeter. If the  voltage  is  low  and  adjustment  of  the variable resistor will not correct the defi- ciency, check the exciter voltage across terminals 5 and 6 of the voltage regula- tor. This voltage will vary but should be about 25 volts DC. If no voltage appears on  the  regulator  terminals  the  voltage regulator is defective and should be replaced. Change 8   5- 3