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The fault on your welder sounds exactly like the one described in this thread. As discussed in Post #2, it is likely that one or more of the power semiconductors ( IGBTs ) has failed and is short-circuit. This causes excess current to flow through the rectifier's soft-start circuit, which includes the varistor, and so that component has been damaged.
There are four IGBTs, which look like this:
and are fastened to the finned aluminium heatsink. You may find that one or more of them is burnt or split. They can be replaced, but please note that other small components ( e.g. Zener diodes, as described in Post #17 ) have probably also failed.
The fault on your welder sounds exactly like the one described in this thread. As discussed in Post #2, it is likely that one or more of the power semiconductors ( IGBTs ) has failed and is short-circuit. This causes excess current to flow through the rectifier's soft-start circuit, which includes the varistor, and so that component has been damaged.
There are four IGBTs, which look like this:
and are fastened to the finned aluminium heatsink. You may find that one or more of them is burnt or split. They can be replaced, but please note that other small components ( e.g. Zener diodes, as described in Post #17 ) have probably also failed.