9 External Trouble Shooting
Circuit breaker trips instantly when mains
voltage is applied
1 Check the rating of the mains supply circuit
breaker. The Weldmatic 355 should be supplied
from a 20 Amp or larger circuit breaker.
Unsatisfactory Welding Performance and
Results
Erratic arc characteristics caused by poor
wirefeed
Erratic wirefeed is the MOST LIKELY cause of
failure in all Gas Metal Arc Welding. It should
therefore be the first point checked when
problems occur.
1 Refer to the Wirefeeder Operators Manual
for wirefeed trouble shooting
2 Check if the consumable wire is slipping in
the drive rolls. Replace the feed roll if it is
the incorrect size or is worn
3 Check that gun cable liner is not too
short and is fitted correctly. Refer to the
wirefeeder Operators Manual for fitting
instructions.
Constant poor arc characteristics
Check that the:
1 Correct polarity has been selected for work
and weld cables (refer page 8)
2 Shielding gas is correct for the consumable
wire in use (refer page 10)
3 Welding circuit is making good electrical
connection. Ensure that the work clamp is
securely tightened onto the work piece so
that good electrical contact is achieved
4 All connections in the external welding
circuit are clean and tight. Problems may
show as hot spots
5 Work piece surface is not contaminated.
Water, oil, grease, galvanising, paint,
or oxide layers can severely disturb the
welding arc and result in a poor weld.
Porosity in weld caused by lack of shielding gas
1 Check that the correct gas flow rate has
been set (refer page 10)
2 Check for leaks in the gas hose. Replace if
leaking
3 Check for leaks in gun/cable assembly, eg.
fractured gas hose, broken or missing ‘O’
rings. Replace as required
4 Check the gun nozzle is free from spatter
and is firmly attached to the welding gun to
ensure that no air is being drawn into the
shielded area.
If the following checks do not identify the
fault condition, the equipment should be
returned to a WIA Service agent. Phone
1300 300 884 for details of your nearest
service agent.
Power source has no output and no
wirefeed when gun switch is closed :
Power light on wirefeeder is off
1 Check equipment is connected to a
functional mains power outlet. Test outlet
using a known working appliance
2 Check the equipment is switched on, ie
‘Coarse’ switch is in position 1,2 or 3
3 Check the circuit breaker at the front of the
power source (press to reset)
4 Check the interconnecting lead is securely
plugged in at the welder and that the lead
is not damaged.
Power light on wirefeeder is on
1 The gun switch circuit is incomplete.
• Check the gun switch for continuity
with an ohm meter when the switch is
pressed. Replace if faulty
• Check the 2 pin receptacles in the MIG
gun adaptor are making contact with
the mating pins from the gun end.
There is wirefeed but no output voltage
when gun switch is closed:
1 Power source may have overheated.
• The Weldmatic 355 welding power
source incorporates an in-built overtemperature thermostat which will
trip if the welding load exceeds the
operating duty cycle. The thermostat will
reset automatically - do not switch the
equipment off as the cooling fan will
assist the resetting of the thermostat
• If problem persists after the cool down
period, call your WIA service agent.
2 There may be broken wires in the control
cables between the power source and the
wirefeeder.
Power source has low weld output
1 Check all electrical connections in the
welding current circuit, including weld
cable, work clamp and gun/cable assembly.