Diodes!

[Rockstar]

Hello fellas! I've got a problem with my Miller big blue 251d (I think it's an early 80s model). During a power outage I had the house plugged into the welder when the power company kicked the power back on. The machine barely arcs now and won't run ac tools. The local welder mech (Chris of Chris's welder service out of Odessa tx) told me he thinks the diodes are fried. He's booked out 6 months + so I can't just have him fix it. Is anybody familiar with this project on this machine?

[griff01]

Hello fellas! I've got a problem with my Miller big blue 251d (I think it's an early 80s model). During a power outage I had the house plugged into the welder when the power company kicked the power back on. The machine barely arcs now and won't run ac tools. The local welder mech (Chris of Chris's welder service out of Odessa tx) told me he thinks the diodes are fried. He's booked out 6 months + so I can't just have him fix it. Is anybody familiar with this project on this machine?

Can't help with your machine problem but I need to tell you that anytime you are running your house (or any other building) on a generator you should be dis-connected from the utility service.
You could have gotten a utility person killed.

Griff

[Rockstar]

Can't help with your machine problem but I need to tell you that anytime you are running your house (or any other building) on a generator you should be dis-connected from the utility service.
You could have gotten a utility person killed.

Griff

I thought I had it turned off at the pole. I'd turned off the wrong pole. Nothing was labeled.

[cruizer]

By would the diodes fry, the auxillary circuit isn't even there. Never the less, your generator stator is indeed fried. Too expensive to repair. So boat anchor

[duaneb55]

Everything griff01 said and if the unit was running when the grid power was restored it should have tripped the breaker(s) or blown the fuse(s) whichever it's equipped with.

However, if the unit was off when power restored, its stator just turned into a massive heater coil and as cruizer pointed out would now be fried just like the 15K Generac generator head I recently changed out for a guy because he did the same thing you did.

[duaneb55]

I thought I had it turned off at the pole. I'd turned off the wrong pole. Nothing was labeled.

That's what your VOM is used for.