If the windings on the main transformer have burnt out, then the welder is indeed beyond economic repair. However, it's worth confirming this with meter readings, because this fault seldom happens.
- Thread starter Ilovewelding23
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Ilovewelding23
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Do i need a really good meter or woyld a cheap diy meter do
Any digital ( or even old-fashioned analogue ) meter will do.
If the welder will switch on and the torch trigger works, you need to check the DC welding voltage between the tip of the torch and the work clamp. As you go up the power ranges, the voltage should start at about 18 volts DC and step up to about 40 volts.
If there is no DC output, you will have to open the welder and find the bolted connections between the thick windings on the transformer ( the secondary ) and the rectifier ( with finned aluminium plates ). If your Murex 245 is single-phase, there will be 2 thick solid wires emerging from the secondary of the main welding transformer and joining to the rectifier. A 3-phase machine will have 3 wires. The voltage at this junction is AC, not DC, and also should step from 20 to 40v.
If there is no AC output from the transformer, but the machine will switch on and the torch trigger activates the contactor when pressed ( i.e. you can hear a loud click inside ), then it may be true that the transformer is faulty. It will be the thinner primary winding that has burnt. If you post some photos of the inside, showing the back of the power selector switch, the contactor ( large relay ), and the transformer, we can identify the primary wires. Then with power off and the machine unplugged, we need to measure the resistance of the transformer primary winding. It will be a very low value, but not a short-circuit, so on the 0-to-200 Ohms range of your meter you should see about 0.7 to 2.0 Ohms.
If the welder will switch on and the torch trigger works, you need to check the DC welding voltage between the tip of the torch and the work clamp. As you go up the power ranges, the voltage should start at about 18 volts DC and step up to about 40 volts.
If there is no DC output, you will have to open the welder and find the bolted connections between the thick windings on the transformer ( the secondary ) and the rectifier ( with finned aluminium plates ). If your Murex 245 is single-phase, there will be 2 thick solid wires emerging from the secondary of the main welding transformer and joining to the rectifier. A 3-phase machine will have 3 wires. The voltage at this junction is AC, not DC, and also should step from 20 to 40v.
If there is no AC output from the transformer, but the machine will switch on and the torch trigger activates the contactor when pressed ( i.e. you can hear a loud click inside ), then it may be true that the transformer is faulty. It will be the thinner primary winding that has burnt. If you post some photos of the inside, showing the back of the power selector switch, the contactor ( large relay ), and the transformer, we can identify the primary wires. Then with power off and the machine unplugged, we need to measure the resistance of the transformer primary winding. It will be a very low value, but not a short-circuit, so on the 0-to-200 Ohms range of your meter you should see about 0.7 to 2.0 Ohms.
oilcooled :)
Pipe Welder, Mechanical engineer
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Have the autostar about 6 months i to found the Oxford 410 very crude on lighter material, maybe I should have ditched the 1mm wire for 0.8mm but the autostar is far smoother across the board. Couldn’t rate it highly enough
Ilovewelding23
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- Ireland
I bought the jasic mig 250 after. I really like the machine . I just have one question on your autostar does the wire inching botton feed the wire faster than using the torch triger
