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253. General Discussion. -The following charts are for the purpose of aiding the projectionist in locating and correcting troubles which may occur on RCA Photophone equipments.

Seven charts are provided. The particular chart to be used in case of trouble depends upon the nature of the trouble and the type of equipment used.

The first chart covers trouble with sound-on-disc and is limited to troubles that might occur in the pickups, pick-up circuits and turntable mechanism. This chart should be used when trouble is encountered in the operation from sound-on-disc, when tests indicate that the rest of the equipment is performing satisfactorily. (Section 255.)

The chart for troubles from sound-on-film is for use in locating trouble due to defective sound heads, photo-cell circuits, or exciter lamp circuits, when the rest of the equipment is operating satisfactorily. (Section 256.)

The third chart is for use in case it is found that the trouble is in the input circuit to the voltage amplifiers, as indicated when no sound can be obtained from either disc or film of one or both projectors when the rest of the equipment is operating satisfactorily. (Section 257.)

The trouble chart for SPU equipments is for use in locating and correcting trouble in SPU equipment amplifiers, and should be used when no sound or poor sound is obtained from both disc and film on PG-3, 4, 6, 7, 8 and 10 equipments. (Section 258.)

The other charts are for use in locating troubles on PG-1, PG-2 and PG-13 equipments (Sections 259, 260 and 261).

Before referring to any of these charts make certain that trouble is not due to a "slip-up" in operation by checking over to see that all switches and rheostats are properly set.

If sound can be obtained from the monitor speaker but not from the stage speaker, the trouble is obviously due to a fault in the leads between the amplifiers and the speakers or due to the stage speakers not being plugged in, or, in the case when only one speaker is used, the fault may be in the speaker itself. See section 228.

254. Use of Trouble Charts. -To determine which trouble chart to use make the following tests, after checking over to make sure no "slip-up" has been made in the operation.


Chapter Fourteen Pages
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