Hobart TR250HF troubleshoot

[Fast Ed]

When I use my machine in AC it works fine. When I switch to DC, when I hit the pedal it kicks the main circuit braker. Anyone with any ideas???

[Red Baron]

Open the unit up and look on the inside cover, should be schmatic. It sounds as if the rectifier is shorted, this device should be on the output of the main transformer.

[Pin Head]

You can check the rectifiers with an ohm meter, but you need to disconnect them first so that you can check them individually. The should only conduct in one direction when you reverse the meter leads. If it is not the diodes, then it could be that the choke is shorted to ground or the AC/DC switch is shorted to ground (or anything else that might be in the DC only side).