267. Motor-Generator Battery Chargers. -Theatres that employ the motor-generator chargers may
encounter any of the following difficulties:
(a) In AC installations, failure of the AC motor to start may be due to:-
No power on the supply line. Main power line switch open. Blown fuses in the
power line. If the motor still fails to start when these conditions have been checked and it is
certain that power is actually entering the charger, check the fuses inside of the cover. See
Figures 26 and 39. These figures show the location of the generator fuses only, but the motor
fuses are similarly mounted.
(b) In DC installations, failure of the DC motor to start may be due to:-
Any of the troubles listed above for the AC motor except that there are no motor fuses inside
of the cover.
Worn brushes. Replace the worn brushes with the spares.
Very dirty commutators. Clean with "00" sandpaper.
Care must be taken when starting the DC charger at the line starting box to close the switch
rapidly. If it is not closed rapidly, and one contact of the switch closes a few moments before
the other, the operation of the line starter is lost.
(c) Generator troubles. These troubles are of course common to either the AC or DC motorgenerator chargers. A considerable variation in the reading of the ammeter located on the
control panel of the charger unit is usually caused by worn or dirty brushes in the generator or
loose connections. Remove these brushes and replace or clean them and also clean the
commutator with a very fine grade of sandpaper such as "00" (Never use emery cloth on a
commutator.) Tighten any loose connections found.
See also sections 53 and 56.
268. Tungar and Rectigon Battery Chargers. -Theatres that are equipped with the Tungar or
Rectigon chargers may experience the following troubles at one time or another:
(a) If, when the battery charger is turned "on," the Tungar or Rectigon bulbs fail to light, make
sure that the main power supply from the street main into the building is closed, and that AC
voltage is actually obtained at the charger. If this is O.K. replace the bulbs with new ones of
the same rating. If this does not correct the trouble call the RCA service engineer.
(b) Should the tubes light up and the ammeter not show any charging current, make sure that
the four-pole battery switch is in the proper position for charging. If this does not correct the
trouble, check the fuses in the battery circuit, and if still no charging current is shown by the
ammeter, replace the rectifying tubes. If no charging current is obtained after all available
tubes have been tried, call the service man.
See also sections 57 and 58.
(D) ROUTINE MAINTENANCE AND TESTS
269. General Discussion. -Although the primary purpose of this chapter is to deal with troubles,
it would not be complete unless something was said regarding the prevention of trouble. Many
of the troubles which are experienced by projectionists can be prevented if the equipment is
properly taken care of and checked over periodically.
The maintenance requirements of the various parts of the equipments were covered in the
chapters describing the parts so that only a summary will be included here.