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Page 30

on towards the horns until the location of the fault is shown by coming to a spot beyond which nothing is heard. Be sure to use very little gain, as otherwise the headset will be overloaded and possibly damaged, and the quality will be spoiled. Use the same method to locate the source of noise or bad quality.

Use a battery and buzzer to test lines for opens or shorts, but NEVER to test amplifier or reproducer circuits, as this may upset the magnetic characteristics of the coils.

On some amplifiers two or more tubes are operated with their filaments in series; if one tube burns out, the others will then be extinguished. If two or more tubes go dark at once, therefore, it should be realized that only one has burnt out. This tube may be located by inspection, or the replacing tube can be tried in each socket in turn.

Troubles Occurring When Testing

Charger Not Functioning (AC Supply Only)
On charger used with AC supply, if a rectifier bulb does not light, its filament may be burned out. Also, a fuse on battery panel may have blown. Clean tube socket. if tube still does not light, replace it by one of spares supplied.

If tubes light but charger does not give output, a fuse inside charger may have blown.

Motor Does Not Start
(1) Is line switch on?

(2) Fuse may have blown in motor control box.

Reading on Motor Control Box Meter Not Within Specified Limits
If reading is too high, on AC, or too low, on DC, it indicates excessive friction at some point in mechanism.

If this is not attended to immediately a bearing may freeze, rendering a projector temporarily useless. Stop machine and oil all bearings immediately abnormal reading is noted on meter, particularly any bearing that seems unduly hot. If trouble persists, notify our service man at once.

Motor Does Not Maintain Regulated Speed Notify our service engineer at once.
Unsteady Pitch in Reproducing ("Flutter")
With film reproduction, there may be dirt on the sprocket in the film compartment of the attachment. If this cause does not exist, notify our service engineer at once.

Reproducer Not Tracking Properly
This occurs when needle jumps from groove. See that reproducer is not dragging on record (See "Replacements - Changing Reproducers") and that it is not hitting anything or otherwise being hindered from free movement. Put in new needle. Try new record. The swivel base on which the reproducer swings is mounted on a bracket, which in turn is clamped to the base by a bolt. See that the bracket is level and that the bolt has not loosened and allowed it to turn.

Excessive or Insufficient Plate Current
If this is noticed on testing the amplifiers, replace the tube showing this condition by a spare.

When two or more tubes on an amplifier all show low plate current at the same time, try replacing the rectifier tubes on that amplifier ( the 41-A amplifier uses the rectifier tubes on the 42-A amplifier). This may also be a sign of defective condensers (see paragraph #6 under heading "Volume Falls Off or Ceases").

No Sound From One Horn (1) Fuse may have blown in cutout box back-stage.

(2) if fuse in cutout box has not blown, replace receiver as described under "ReplacementsChanging Receivers".

Volume Falls Off or Ceases (1) If system is a double one, having emergency amplifier equipment, cut in emergency amplifiers by means of key on system transfer panel. If this clears trouble, continue use of emergency amplifiers until our service engineer repairs or replaces defective regular amplifier, unless trouble can be cleared as will now be described.