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Jim Davey
R H Davey Welding Supplies Ltd
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- Southampton
You need to disconnect the input to and output from the rectifier (Mark the wires so you don’t loose the orientation) then put your multimeter on diode test and put the probes between adjacent plates you should read OL (over range) one way and 400ish in the opposite polarity. Do this on all 4 plates and if any read in both directions you have a short.
Jim Davey
R H Davey Welding Supplies Ltd
- Messages
- 5,734
- Location
- Southampton
More things it could be. Check the rating plate, you are looking for the Uo (open circuit voltage, probably about 34v) and make sure you have the full voltage you should be getting. Switch to max volts, let off the pressure roller so wire won’t drive, set your meter to measure dc volts and put the positive probe on the torch tip and the negative probe on the earth. Then trigger he set to see the volts. Should be bang on or you have a problem. Also you could check for voltage drop across the Contactor, there should be almost none. Find a line in and the line out on L and N. Set meter to AC volts and. You put a probe on the N in and out and trigger the set to pull the contactor in then read voltage which should be very low, do the same for the L contact. Anything less than a volt is good. If you can read over 2-3 volts the contactor is duff. The tests take a fraction of the time it’s taken me to write this 
Rating plate says Uo=17.5-37 V. I measured 17.3 on the lowest setting and 36.1 on the highest so about a Volt under. Is that a problem?
As for the contactor I only have the three phases going through it so no N. But I measured across for each phase and it read zero. Not sure if that is what you meant.
Maybe I should make a Voltage test under load?
Something called GB-74, 0.8 mm.
"GB-74™ is our best-selling welding wire. It is a silicon manganese alloy, copper coated welding wire, designed for MIG/MAG welding in non-alloy and low alloy steels and welded using pure CO2 or a mixture of gases."
Think you’re chasing your tail a bit. When you switched to push and stopped trying to lay down a big, fat bead (Picture #4 half way along) I don’t think you were a million miles away from okay, without practicing the series of ‘e’ or similar to get a larger bead without that convex profile using 0.8.
Bit distracted as Nigella’s on the telly cooking. I’m watching like a dog outside a butchers.
Anyway, yes. For tutorials check out the guides on here and Weldmonger
