Lincoln Electric RANGER 305 D Service Manual page 55

RANGER 305D THEORY OF OPERATION
Remote output control:
The Weld control PC board automatically detects when a remote
control potentiometer is connected to either of the Amphenols. In
"CC-STICK", "DOWNHILL PIPE" or "CV-WIRE" modes, the front panel
output control is disabled when a remote control device is connected.
In "TOUCH START TIG" mode, the front panel output control poten-
tiometer is used to set the maximum output value. The remote poten-
tiometer varies the output from minimum to maximum value set by
the front panel control.
Electronic Output Contactor:
The operator also has the ability to control when power is delivered to
the output studs. This is accomplished by signaling the control PC
board when to send the PWM signal to the chopper module. Turning
the PWM signal on or off has the same effect as activating or
deactivating an output contactor, and is accomplished by closing the
circuit between the #2 and #4 leads. The welding terminal switch
closes this circuit when it is placed in the "WELD TERMINALS ON"
position. When the switch is placed in the "REMOTELY CONTROLLED"
position, the circuit is closed by a TIG foot pedal, a control cable type
wire feeder, or other remote control devices that can be plugged into
either the 6 pin or the 14 pin Amphenol.
Digital Meters:
Two identical digital displays are connected to the control PC board
and are used to indicate weld outputs Amps and Volts. When no
current is flowing, the machine is in "preset" mode and only one of
the displays will be active. If mode switch is set for "CV-WIRE", only
the volts display will be active; in all other modes, only the amps
display will be active. When weld current is flowing, both displays will
indicate actual weld volts and amps.
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