Tweco 300 MST Arcmaster - Manual (Page 51)

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