Welder transformer zapped

the pict · Sep 4, 2018

Hi all I need a bit of help from the wise wizards I mate has a heavy duty mig welder which gave up the ghost on him I have had it apart the transformer that supplies 24vDC has no continuity through the primary and on close inspection the "in" if you like has detached itself from the terminal pin, I have tried to source one from Kemppi direct but it takes over a week just to place an order, now at 230V AC primary and 24 V DC secondary I can source one of a generic nature but how important is the VA there is no indication on the tranny and the data plate is to me anyway confusing as there is no direct ref to the 24V tranny this plays no part in the actual welding process it just supplies the contactor A1 A2 coil direct its a Kemppi 9777803
TA

telectrix · Sep 4, 2018

if it's just feeding a contactor coil the amps will be minimal

the pict · Sep 4, 2018

Thanks I kinda had that feeling as the coil is only energised during a weld via the torch trigger,
P

westward10 · Sep 4, 2018

The secondary must be rectified as the transformer will only output ac.

Lucien Nunes · Sep 4, 2018

If you can see the detached end of the primary winding it might be fixable. If you need to insulate the joint, you'll want to solder to the winding first, then slide on the sleeving, then solder to the pin. Use a heat shunt to prevent the winding desoldering. If it has adequate clearance to remain bare then you can solder to the pin first, which will support the joint and won't desolder while you connect to the winding. Many winding wires are self-fluxing but don't breathe the fumes.

If searching for a replacement, many PCB-mount and chassis-mount transformers are pretty interchangeable. If the DC supply voltage is 24V and there is no regulator, the transformer secondary will be about 18V AC. Pics would help.