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12 UNIT HAS CRASHED
When a unit has crashed, perform the following checks:
• Check whether cable insulation is damaged.
• Check for ferrite fragments in the unit. Ferrite cores of transformer T1, reactor L1 or HF
reactor L2 may be broken.
• Inspect ferrite cores of power transformer T3, reactor L1 and HF reactor L2 for visible
cracks.
• Inspect metal enclosure for indents which may cause undesirable electrical connections.
• This often affects mounting locations of weld current sockets.
13 UNIT SWITCHES OFF AFTER A SHORT TIME INTERVAL
Module A1 (connector X9-1, X9-3) is always connected to the weld current sockets by two sepa-
rate cables, and there is a monitor for excessive DC or AC voltages (see section A1-6).
The inverter control board A8 is always connected to the DC output voltage (connectors X3.6 and
X3.8) and this voltage is regulated to approx. 90 V. As long as no current is flowing, i.e. no arc is
started, no AC voltages are generated at the output.
Nevertheless, if a safety trip occurs, the inverter power supply is switched off within about 0.2 sec-
onds after the inverter starts. Error code 5 is then shown on the display.
The inverter doesn't start until shortly after power-on, when the control unit sends a request. As a
check, the control panel can be set so that the inverter is still turned off after power-on. It can then
be started by selecting an electrode mode or by pressing the Torch button.
In electrode mode, the inverter is turned off as long as the current setting is zero. In TIG mode,
the inverter is turned off until a start is initiated by pressing the Torch button or through the remote
regulator.
Possible fault sources:
• DC output voltage (in function diagram denoted by UG+) is not connected to the inverter
control board A8.
• Cable harness.
• No-load voltage regulation on inverter control board A8 is defective.
• Fault in transformer shunt T2 or in its -15 V supply; in this case the inverter control board A8
assumes that "current is flowing" and turns off the no-load voltage regulation.
• Fault in the monitoring circuit on A1-6.
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