Phase Linear 400 - Rear Panel Description; Amplifier Inputs; Speaker Connection Terminals; Installation Instructions

Step #6. Тһе final test is the short circuit test.
Plug the amplifier A.C. line cord into a variac. Set the variac
to 0 volts. Short circuit the output terminals with a jumper,
and drive the input of the amplifier at 20 Hz. Slowly increase
the variac from 0 (zero) volts to 117 volts. Remove the short
circuit jumper and verify that the amplifier resumes normal
operation.
CLEANING THE AMPLIFIER
Full strength sudsey ammonia soaked on paper towels
should be used to clean the front panel occasionally. This
removes dirt and oily films and will restore the original luster
of the front panel.
SECTION IV
SERVICE HINTS
Analysis of amplifier service problems over the past
two years has resulted in the following table of amplifier
failure modes.
Typical repair problems: (In order of decending fre-
quency of occurance.)
Simple open fuse.
Stuck or sticking V.U. meters. Burned out lamps.
Bad solder connections on circuit board.
Shorted out transistors.
Defective zener diode on the circuit board.
Defective transistors on circuit board.
Shorted power rectifier.
Mechanical failure of fuse holder.
Open electrolytic capacitors.
No known resistor failures.
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No known mylar capacitor failures.