Figure 8-20-Continued. Figure 8-20 TM 5-6115-323-14 TO  35C2–3-385-1 overheating and for cracks, breaks, defective threads, and other damage. (3) Inspect the variable resistor for proper operation and for proper resistance. Resistance should vary smoothly from 0 to 1,500 ohms when the unit is turned through its range. Replace a defective  variable  resistor. (4) Inspect  wire  leads  for  breaks,  poor  connet- tions at the terminals and for broken or frayed insulation.  Replace  defective  wire  leads. (5) Inspect the voltage regulator for cracks, breaks, signs of overheating, and other damage. Replace  a  defective  voltage  regulator. NOTE Apply one coat of varnish meeting  specification MIL-V–173 to the exposed circuit ,area of the voltage regulator. c. Assembly and Installation. (1) Refer to figure 8-2 and assemble thc control box. (2) After assembly of the cotrol box, apply one coat of clear varnish meeting specification MIL-V-173, Type II. (3) Install the control box (pare 6-3). d. Test. Test the DC control box components as follows: (1) Voltage  regulator. (a) Disconnect load cabics 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 deficiency, check the exciter voltage across terminals 5 and 6 of the voltage regulator. This voltage will vary but should be about 25 volts. If no voltage appears on the regular terminals, the voltage regulator is defective and should be replaced. (d) If voltage across regulalor terminals 5 and  6  is  satisfactory,  stop  the  genrator  set,  at– tach the load cables, and restart the set. (e) If voltage is still not satisfactory, replace the voltage regulator and repeat steps  (a) thru (d) above. (2) Circuit breaker. (a) Attach a variable load to the output terminals and start the generator. (b) Move circuit breaker to ON position and observe the load meter and volumeter. Reading should be 28 V at 100% load. (c) Adjust the variable load until a reading of 125% is obtained on the load meter. The circuit is designed to trip at 125% maximum load. (d) If the circuit breaker trips below 125% maximum load, replace it. (3) Capacitor   (noise   suppression). NOTE The only accurate way to test a capacitor is by putting it on a capacitor tester. However, you can tell if a capacitor is working by the following method. (a) Stop the generator  set  and  disconnect the  lead-in  terminal  to  the  capacitor. (b) With multimeter on the high scale ohms setting, touch the test probes to the input learning and the capacitor metal case, then reverse the probes. The multimeter will give a momentary reading then fall back to 0. (c) If this reading does not occur, then replacc the capacitor. (4) Variable resistor (DC). (a) Stop generator set and disconnect  terminal 1 on the  voltage  regulator. (b) Insert multimeter probes across the two outside connected terminals of the variable resistor. With the variable resistor in the full counterclockwise position, slowly turn the control knob to the full clockwise position. This reading should move smoothly from 0 to 1500 ohms ± 20% as the variable resistor is rotated to the full clockwise position. 8-5