Tweco Hefty II CC CV Voltage Sensing Wire feeder - Manual (Page 28)

PROCEDURE:
WARNING: ELECTRIC SHOCK
CAN KILL. Make certain the
power source and wire feeder
are both turned OFF before be-
ginning the procedure.
1. Using a 1/4" nut driver or socket, remove the
exterior cover to expose the motor control
printed circuit board (See Figure 5-2).
2. Locate component R68 (“Burnback”) on the
motor control printed circuit board (See Fig-
ure 5-2). The best procedure is to make only
slight adjustments until the amount of burn-
back is acceptable. Component R68 has a
single turn (360°) range of adjustment.
To increase burnback time, adjust com-
ponent R68 clockwise.
To decrease burnback time, adjust com-
ponent R68 counterclockwise.
3. Replace the exterior cover.
Calibrating Wire Feed Speed
Meter:
The motor control printed circuit board contains a
component that permits calibration of the wire feed
speed displayed on the analog meter. If the wire
feeder was ordered with a wire feed speed meter
installed, the meter was calibrated at the factory.
However, the wire feed speed meter will have to
be calibrated or recalibrated if one of the following
occur:
•
A wire feed speed meter is installed in the
field as an option.
•
The motor control printed circuit board is
replaced.
•
The drive motor is replaced.
PROCEDURE:
WARNING: ELECTRIC SHOCK
CAN KILL. While calibrating the
wire feed speed meter, voltages
as high as the open circuit volt-
age of the power source will be
exposed. Use caution, and fol-
low all instructions accordingly.
1. Place the CC/CV mode switch in the CV
position.
2. Using a 1/4" nut driver or socket, remove the
exterior cover to expose the motor control
printed circuit board (See Figure 5-2).
3. Adjust the wire feed speed control knob to
position 5.
4. Cut off the welding wire at the tip of the
welding gun.
5. Depress the inch switch or the gun switch on
the welding gun for exactly 15 seconds.
6. Cut off the welding wire at the tip of the
welding gun and accurately measure.
7. Use the formula below to calculate the wire
feed speed in inches per minute (IPM):
IPM = 4 x Wire Length Measured In Step
#6
(For Example: If 125 inches of wire feeds in 15
seconds, multiply 125 x 4 = 500 inches per
minute)
8. Now, with the inch or gun switch depressed,
adjust component R46 on the motor control
printed circuit board until the analog meter
displays the IPM calculated in Step #7 (See
Figure 5-2).
9. Replace the exterior cover.
10. Place the CC/CV mode switch in the proper
position (See “Internal Controls And Con-
nections” section of this manual).
Protection And Safety Circuits:
The following protection and safety circuits come
standard with this wire feeder and are designed to
protect (by disabling the wire feeder) against unfa-
vorable operation and/or equipment damage.
1. Undervoltage Protection - If the input voltage
drops below the specified voltage range for
an extended period of time, an electronic
circuit will activate, and the wire feeder will
not operate. The undervoltage protection cir-
cuit will automatically deactivate when the
input voltage enters an acceptable range.
2. Overvoltage Protection - If the input voltage
rises above the specified voltage range for
an extended period of time, an electronic
circuit will activate, and the wire feeder will
not operate. The overvoltage protection cir-
cuit will automatically deactivate when the
input voltage enters an acceptable range.
430429-456
OPERATION
November 17, 1999 5-3