Clarke AT150 Arc-Tig welder - circuit diagram?

[633Squadron]

Is there anywhere that I can obtain a circuit diagram for a Clarke AT150 Atc-Tig welder? I believe that it's an obsolete model, so I'm not holding my breath about getting anything from Clarke Support about it.

I know that it doesn't work properly, but I might have a better idea what might be wrong when I open it up and take a look inside over this weekend. I'd like to draw on the knowledge of anyone that has had experience of repairing similar Clarke models to the AT150 and what possible faults that I should look for.

 

[633Squadron]

OK, from a quick look over this morning, the symptoms I have are these. Switch on, it works (sort of) and the fan runs, I can see and hear the relay switch over, but the output voltage appears to be about 0.5v DC. Turning up the power setting causes a slight dip in the fan speed, but no increase in output. What should I be checking next?

 

[633Squadron]

Anyone?

 

[Bill Edwards]

I think I would start by checking that the relay is working - not just clicking, but that the contacts are actually allowing current through. I'd also check that there is power to those contacts (i.e that the relay is switching something on).
If that all seems fine I would be testing the voltage into the big transformer, and the output. I'd also check the diodes that turn the AC into DC to make sure they're OK.
Plus it's good to just look things over and make sure no connections are loose, sometimes it's the most simple things that cause issues.