Hello, and welcome to the Forum.
The large black plastic-potted relay on the PCB ( P.No. HF8509-1 ) has a 24vDC coil which is controlled by circuitry on the PCB. The contacts are rated at 60A, and are bolted to two wires which provide the live AC feed to the welding transformer. There may be / are other relays in the machine, but I would initially suspect that one on the PCB. Either it is not moving correctly, or the contacts have burned and no longer conduct.
To confirm this, you need to unbolt the blue ring tags on those two white leads and connect the two leads together. This will bypass the suspect relay, and the machine may start running, just as if you had pressed the torch trigger.
** These two wires carry a live AC mains feed, so be careful and do the work with the machine powered off and unplugged, and insulate the wire junction before plugging in and testing.**
If you just use a screw to join the two ring tags, when you power-on the main power switch the whole welder will come on, as if you had powered it up with the torch trigger pressed. It may be safer to temporarily connect those two tags to a suitable mains switch - a pushbutton, toggle, or rocker switch of adequate rating. Insulate the connections at the back of the switch. Then, with that switch "OFF", you can first power up the welder, and then operate the temporary switch. That will bypass the relay, and if the machine now works normally it will confirm that the black relay is faulty.
The large black plastic-potted relay on the PCB ( P.No. HF8509-1 ) has a 24vDC coil which is controlled by circuitry on the PCB. The contacts are rated at 60A, and are bolted to two wires which provide the live AC feed to the welding transformer. There may be / are other relays in the machine, but I would initially suspect that one on the PCB. Either it is not moving correctly, or the contacts have burned and no longer conduct.
To confirm this, you need to unbolt the blue ring tags on those two white leads and connect the two leads together. This will bypass the suspect relay, and the machine may start running, just as if you had pressed the torch trigger.
** These two wires carry a live AC mains feed, so be careful and do the work with the machine powered off and unplugged, and insulate the wire junction before plugging in and testing.**
If you just use a screw to join the two ring tags, when you power-on the main power switch the whole welder will come on, as if you had powered it up with the torch trigger pressed. It may be safer to temporarily connect those two tags to a suitable mains switch - a pushbutton, toggle, or rocker switch of adequate rating. Insulate the connections at the back of the switch. Then, with that switch "OFF", you can first power up the welder, and then operate the temporary switch. That will bypass the relay, and if the machine now works normally it will confirm that the black relay is faulty.
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