J- POWER SUPPLY (CR-102)
A full wave rectifier circuit employing a silicon rectifier in a bridge circuit
provides plate voltage for both amplifier channels. Power for the output
stages is supplied directly from the rectifier, while the low level stages re-
ceive plate potential filtered by R- 148- 149 and C- 116A-B-C. Switch S- 107
is the main power switch; S-108 the servo on-off control, removes the line
excitation from the motors and de-energizes the input choppers.
K. MOTOR - POTENTIOMETER
The servo motor is a Diehl 5-watt, 2-phase induction motor, one phase of
I .. which is energized from the AC line, the other being excited in phase quadra-
ture from the amplifier output. Direction of motor rotation is determined by
whether a leading or lagging 90" relationship exists. A pinion on the motor
shaft meshes with a large fiber gear, which in turn drives a 3-turn precision
potentiometer through a friction clutch. The reduction is 20: 1. Also carried
on the drive shaft is a 3-turn counting stop, which limits the shaft rotation,
protecting the potentiometer from damage.
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