Tweco 250 Weldskill MIG - Manual (Page 42)

8-4 Manual No 0-5072
weldskill 250, 350 service
December , 2008
5 Irregular weld shape A
B
C
D
Incorrect voltage and current
settings. Convex, Arc voltage
too low
Concave, voltage too high
Wire is wandering
Incorrect shielding gas
Insufficient or excessive heat
input
A
B
C
D
Adjust voltage and current by
adjusting the Voltage Control
switch positions and the
Wirespeed control knob.
Replace contact tip
Check gas selection
Adjust the Wirespeed control knob
or the Voltage Control switch.
6 Arc does not have
a crisp sound that
short arc exhibits
when the wirefeed
speed and voltage are
adjusted correctly
The MIG torch has been
connected to the wrong voltage
polarity on the front panel
Connect the MIG torch to the
positive welding terminal (+) for
solid wires and gas shielded flux
cored wires.
7 Weld cracking A
B
C
D
E
Weld beads too small
Weld penetration narrow and
deep
Excessive weld stresses
Excessive voltage
Cooling rate too fast
A
B
C
D
E
Decrease torch travel speed
Reduce current and voltage and
increase the MIG Torch travel
speed or select a lower penetration
shielding gas.
Increase weld metal strength or
revise design
Decrease voltage by reducing the
Voltage Control switches.
Slow the cooling rate by
preheating part to be welded or
cool slowly.
8 Cold weld puddle A
B
C
D
Faulty rectifier unit
Loss of a phase in the Mains
supply voltage.
Loose welding cable connection.
Low Mains supply voltage
A
B
C
D
Have an Accredited CIGWELD
Service Provider test then replace
the faulty component.
Check mains power
Check all welding cable
connections.
Contact supply authority
8.08 Power Source / Wirefeeder Problems
FAULT CAUSE REMEDY
 Mains supply voltage
is ON. Indicator light
is not lit and welding
arc can not be
established.
A
B
Primary fuse is blown.
Broken connection in primary
circuit.
A
B
Replace primary fuse.
Have an Accredited CIGWELD
Service Provider check primary
circuit.
2 Mains indicator
light is not lit but
welding arc can be
established.
Burnt out Indicator light. Have an Accredited CIGWELD
Service Provider replace Indicator
light.
3 Mains supply voltage
is ON and Indicator
light is lit but when
the torch trigger
switch is depressed
nothing happens.
A
B
Torch trigger switch leads are
disconnected.
Circuit breaker tripped
A
B
Re connect Torch trigger switch
leads
Reset Circuit Breaker(s)