TABLE V. Functions of Electronic Components (Figs. 7 & 9) (Continued)
(20, 000 ohms, 10 watts, fixed) Used with voltage regulators V103 and
V104 to regulate voltage to amplifier V105 and wire feed speed poten-
tiometer R111 in Wire Feeder.
(330, 000 ohms, 1 watt, fixed) Voltage dropping resistor in plate cir-
cuit of VI05A which limits voltage to grid of V105B.
(1 megohm, 1 watt, fixed) Prevents current flow to grid of V105B.
(220,000 ohms, 1 watt, fixed) Prevents current flow to grid of V105A.
(50,000 ohms, 10 watts, fixed) Voltage divider across output of
tachometer-generator on motor shaft. Voltage across R108 with that
of capacitor C104 improves response of motor to sudden changes in
load. Voltage across R109 is added to that of wire feed speed poten-
tiometer R111 in Wire Feeder (hand-set for desired speed), and
amplified by V105. The result is then applied through saturable re-
actor SX101 to thyratron V101 to alter motor speed.
(30.000 ohms, 10 watts, fixed) Supplies necessary reference voltage
to wire feed speed potentiometer in Wire Feeder.
(20,000 ohms, 4 watts, variable) Used for fine calibration of wire
feed speed potentiometer Rlll in Wire Feeder.
Part of phase-shift circuit for control of wire feed motor.
(Double-pole, double-throw) Control circuit switch connects Control
components to 115 VAC supply.
In SCRATCH START position, only gas and water are supplied to gun
when gun trigger is depressed, and wire must be scratched on work-
piece to supply weld current and wire. In RUN-IN position, wire,
weld current, gas, and water are supplied at gun when gun trigger is
Supplies 25.2 VAC to gun controls and coils of CR103 and CR104.
AC voltages: 180 V to
thyratron V101 plate; 50 V to phase-shift
windings in motor-run
circuit; 2.6 V to thyratron filament; 640 V
to rectifier V102; 5 V to
rectifier filament; and 6.3 V to amplifier
Thyratron C3J controls speed of wire feed motor by regulating
voltage in motor-run circuit.
5Y3 full-wave rectifier rectifies input AC for use by motor control
0B3 voltage regulators keep output voltage of thyratron V101 con-
stant for motor control circuit.
12AT7 dual triode combines output voltage of tachomete r-generator on
Wire Feeder motor (voltage equivalent of motor speed) with voltage
equivalent of desired wire feed speed (hand-set on wire feed speed
potentiometer) for use by motor control circuit.