MAINTENANCE - TM-10-3930-607-150108

ELECTRICAL

Figure 28.

necessary.

However, if the voltage fluctuates as

evidence by an unsteady voltmeter reading when

checking the voltage setting, the contacts may have

Figure 27.

excessive resistance or may be sticking and they,

therefore, should be cleaned.

(Fig. 27) Turn variable resistor to the open or "full

resistance" position, and leave the ignition switch

CAUTION: Before cleaning contacts, make sure the

in the "off" position.

unsteady voltage is not being caused by loose

connections or high resistance elsewhere in the

b. Slowly decrease resistance and note closing

system.

voltage of the relay. Adjust by bending heel iron.

(Fig. 28) NOTE: If the field relay unit does not

2. The contacts on the voltage regulator unit are of

have an armature stop, a point opening check is

a soft material and must not be cleaned with a file, A

not required.

strip of No. 400 silicon carbide paper or equivalent

folded over and then pulled back and forth between the

D. MAINTENANCE

contacts is recommended as a satisfactory method of

cleaning. After cleaning, the contacts should be washed

1. The voltage regulator contacts should not be

with alcohol to remove any residue. If the voltage

cleaned unless the electrical performance indicates it is

control has not improved, repeat the cleaning and

necessary. A sooty or discolored condition of the

washing process.

contacts is normal after a relatively short period of

operation and is not an indication that cleaning is

3. To clean the field relay contact,. use a thin, fine

cut, flat file. Remove only enough material to clean the

points.

B-71