16
Pulsed arc applications
The main application for pulsed arcs is unalloyed steels within
the performance range of the transition arc. At the lower end
of the performance range the pulsed arc cannot fully replace
the short-circuiting arc. The reason here is the continuous arc
that occurs in the primary current phase. This phenomenon
does not exist with the short-circuiting arc. An exception to
this is when welding aluminium and aluminium alloys. Nor-
mally, these materials can only be reliably welded using a
pulsed arc. In the upper performance range, the pulsed arc is
preferable to the sprayer arc, in particular for welding alumin-
ium materials and high-alloy steels.
Please keep attention to the current safety regulations at all
care and maintenance works.
The machine requires minimum of care and maintenance.
Only a few items should be checked to ensure a trouble free
long term operation:
– Check the mains plug, mains cable, and the welding
torch as well as the ground connection for damage from
time to time.
– Once or twice a year please clean the machine with dry
low compressed air. Switch off the machine and pull out
the plug first. Open the case of the machine and clean
also inside - please avoid to blow directly onto electronic
parts – they could be damaged.
15 Care and maintenance
16 Troubleshooting guide
Symptom
Cause
Remedy
Torch too hot
Insufficient coolant through flow due to pollution into
coolant
Swill the waterhoses of the torch in opposite
direction
Contact tip is not tight
Check it
No function when torch
button is pressed
Nut of the torch hose is not tight
Tighten it
No connection of the control cable in the torch hose
Check and change if necessary
Overload of the unit and thermal protection is in
function
Allow unit to cool down at no load
Irregular wire feeding or
wire welds to the con-
tact tip
Wire electrode is tight at the spool
Check and change if necessary
Burr at the wire beginning
Cut the wire beginning again
Irregular wire feeding or
no wire feeding
Wrong contact pressure at the wire-feed rolls
Adjust it as described in the manual
Torch defect
Check and change if necessary
No brass pipe in the central connection or is dirty
Install or clean the brass pipe
Bad quality of welding wire
Check and change if necessary
Rust formation at the welding wire
Check and change if necessary
Torch liner is dirty inside
Disconnect the torch from the machine, screw
off the contact tip and clean the liner with com-
pressed air
Torch liner is dejected
Check and change if necessary
Motor brake adjusted to strong
Adjust as described in the manual
Unit switches off
Duty cycle overloaded
Allow the machine to cool down
To less cooling of unit parts
Check the air in and outlet
Cooler or hoses defect
or pump is damaged
Freezed systems due to less anti freezer liquid
Contact the nearest service facility
Arc or short circuit
between contact tip
and gas nozzle
Spatter built up inside the gas nozzle
Remove it with special pliers
Unstable arc
Wrong diameter of contact tip or worn out
Change contact tip
The DP20 operating
panel is completely dark
Phase missing
Check the unit at another power outlet. Check
power cable and mains fuses/circuit breakers
No shielded gas
Gas cylinder empty
Replace it
Defect torch
Check and replace it
Pressure reducer dirty or defect
Check and replace it
Valve of gas cylinder defect
Replace the gas cylinder
Shielded gas switches
not off
Valve of gas cylinder dirty or does not close
Remove torch and pressure reducer and clean
it with compressed air
Not sufficient shielded
gas
Wrong adjusted quantity of shielded gas
Adjust right as described in the manual
Dirty pressure reducer
Check valve
Torch, gashose blocked or not air-tight
Check and change if necessary
Shielded gas is blow away from draught
Avoid draught
Summary of Contents for MULTIMIG 400puls
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