Troubleshooting an Old Arc Welder

[treqilio]

I am troubleshooting an old arc welder that won't arc! I'm not even sure where to begin the troubleshooting process. There is power going in, I have verified it.

[Cheller]

I am troubleshooting an old arc welder that won't arc! I'm not even sure where to begin the troubleshooting process. There is power going in, I have verified it.

What kind of old welder is it? What are the symptoms? It just doesn't weld?

[treqilio]

It is a Westinghouse Torpedo welder. I have 480V three phase power going in and when I strike the arc nothing happens. It sounds like it is alive like it always has, but i have lost arc completely.

[Cheller]

Always start with troubleshooting basics. Since you didn't go into detail, check continuity of the cables, the ground and the actual arc lead first. I would make sure that nothing simple is overlooked like the ground termination or the connection in the handle. Once you have verified that these are good, you can move up to the terminals on the output of the welder and check voltage output. I would think the voltage should be marked.

[treqilio]

The cabling on the output of the welder is in poor shape, but it checks good for continuity. I have tried putting a voltmeter on the output lugs and I'm not getting any voltage there at all. Where should I go next with my arc welder troubleshooting 101?

[3rdshiftguy]

Wow, the welder schematic is dated 7/23/46. Maybe it's time to upgrade your welder? That's 61 years old. Harry Truman was president when this welder rolled off the assembly line at Westinghouse.

[treqilio]

I actually have another welder that we're using now, but this was a workhorse so I thought I would try to repair it.

I've attached the main schematic for troubleshooting, any thoughts on the welder circuitry?