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1342 HANDBOOK OF PROJECTION FOR
meters draw very high current, causing a heavy drop in the resistance or in the transformers, which results in low voltage readings. You must know your meter
before attempting to make such tests as these.
Using a Weston 280 voltmeter or its equivalent, 45 volts on V2, or 90 volts on V3, shows the transformer primary to be shorted. If it is the V2 at fault, then the input transformer is indicated. If it is the V3, then the output transformer is at fault.
WARNING. — Although it is almost impossible, still this same condition could be set up by a wire or some current-carrying object coming into contact with terminals 2 and 5 of the input transformer.
It also is possible for either half of the primary to become shorted, which would result in a reading of between 35 and 45 on V2 and between 65 and 90 on V3. A short of either the whole or half of the primary would manifest itself in visible form at the terminals of the two transformers.
A ground on the battery side of the coupling of either the resistance or the transformers would blow a fuse in the PEC battery box when the amplifier switch is closed. A ground in the wiring between the switch and the amplifier will blow a fuse.
Should this occur, open the switch and replace the blown fuse, the location of which will of course indicate the circuit at fault, except the fuse on the 45-volt wire, which supplies current for both VI and V2.
TO FIND THE GROUND.— With the switch in open position, connect the positive terminal of the voltmeter to one of the 90-volt terminals of the switch, on the