44
Table 12.2 Fault Analyses
No. Fault Cause Remedy
Indicator lamp NL failure, improper
contact
Check contacting sections. Replace the
indicator lamp NL.
1 Power supply indicator lamp does not
light even if the switch in the switch gear
is turned ON.
Improper primary input contact Check the connections.
Cooling fan or control circuit failure Check the cooling fan.
Indicator lamp NL
lights.
Control circuit fuse F1 blown Investigate the cause and replace the fuse.
2 Cooling fan does
not rotate even if
power supply
switch is turned
ON.
Indicator lamp NL
does not light.
Refer to No. 1.
−
Insufficient gas regulator pressure Check the gas pressure.
No gas flows even
if the gas adjusting
position is set.
Magnetic valve MV clogging or
breakdown
Check the magnetic valve MV. Replace
it if necessary.
Gas flows in gas
adjusting position.
Starting relay 1Y
operates.
Gas circuit failure Check the printed boards (MB2 and 1F).
Connector improper contact Check the connector.
Staring relay 1Y improper contact Check the starting relay 1Y. Replace it if
necessary.
3 No gas flows even
if welding start
signal turns ON.
Starting relay 1Y
does not operate.
Control transformer failure Replace the transformer TR.
Magnetic contactor deteriorated
insulation
100 MΩ
Replace the magnetic contactor.
High-voltage transformer failure or
malfunction
Check the transformer and printed boards
(HV2 and MX).
Leakage of high voltage from torch
cable and torch
Reinforce the insulation.
Leakage of high voltage from
cooling water path
Reinforce the insulation.
Secondary inverter section failure Check the transistors (T21 and T22).
Replace them if necessary.
Starting relay 1Y
operates.
Primary inverter section failure Refer to No. 10.
4 High voltage is not
generated even if
welding start
signal turns ON.
Starting relay 1Y
does not operate.
Refer to No. 3.
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