Power Source Problems - Thermal Arc ARCMASTER 300 MST Operating Manual

9.05 Power Source Problems

Description
1 The welding arc
cannot be established.
2 Maximum output welding
current
cannot be achieved with
nominal Mains
supply voltage.
3 Welding current reduces
when welding.
4 No gas flow when
the torch trigger switch is
depressed.
5 Gas flow won't
shut OFF.
6 The TIG electrode has
been contaminated due to
the gas flow shutting OFF
before the programmed
POST-FLOW time has
elapsed.
Possible Cause
A The Primary supply voltage has
not been switched ON.
B The Welding Power Source
switch is switched OFF.
C Loose connections internally.
Defective control circuit
Poor work lead connection to the
work piece.
A Gas hose is cut.
B Gas passage contains impurities.
C Gas regulator turned OFF.
D Torch trigger switch lead is
disconnected or switch/cable is
faulty.
STD SLOPE
A Weld Mode ( ,
REPEAT SPOT
or ) was changed
before POST-FLOW gas time had
finished.
B Gas valve is faulty.
C Gas valve jammed open.
POST-FLOW
D control is set
to 60 sec.
The Weld Process Mode (STICK,
HF TIG or LIFT TIG) was changed
POST-FLOW
before gas time had
finished.
45
Remedy
A Switch ON the Primary
supply voltage.
B Switch ON the Welding
Power Source.
C Have an accredited Thermal Arc
Service Agent repair the connection.
Have an accredited Thermal Arc
Service Agent inspect then repair the
welder.
Ensure that the work lead has a
positive electrical connection to the
work piece.
A Replace gas hose.
B Disconnect gas hose from the rear of
Power Source then raise gas pressure
and blow out impurities.
C Turn gas regulator ON.
D Reconnect lead or repair faulty
switch/cable.
, A Strike an arc to complete the
weld cycle.
OR
Switch machine OFF then ON to reset
solenoid valve sequence.
B Have an accredited Thermal Arc
Service Agent replace gas valve.
C Have an accredited Thermal Arc
Service Agent repair or replace gas
valve.
POST-FLOW
D Reduce
Do not change Weld Process Mode
before the POST-FLOW
gas time had finished.
time.