No Schematics available for this device so I made some up including a PCB mask in case anyone needs to make the control board PCB

Image of assembled circuit board:

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Power resistance:

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Transformer:

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Most of time the relay for the wire feeder breaks (5A type):

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It's on this place:

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You can replace it with following relay (8A type):

"Printrelais 24V DC | 2 Wechsler | RT424024 Steckrelais | 24 VDC | 24V"

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It can be found at a German store (SCHRACK).