I've acquired this Supermig 170/1 with a fault. All seems to work ok, switch on, fan works, pull trigger wire feeds. But when you try and weld,it seems as there's not enough power, it just burns back the wire each time. I checked the diodes out, and I thought they seemed ok, could it be a transformer problem, if so, can I fault find it.?
- Thread starter Dave-M
- Start date
It is unlikely to be the transformer, they rarely fail. However, the secondary winding on the transformer is aluminium, not copper, and the bolted connections can corrode or crumble. They may look OK externally, but I would suggest opening and checking all the connections in the high-current welding path.
Then measure the voltage between the torch tip and the clamp on the work return cable. It should step up from about 15v to 30v DC as you increase the power settings.
Then measure the voltage between the torch tip and the clamp on the work return cable. It should step up from about 15v to 30v DC as you increase the power settings.
View media item 11002This is the internals of the welder. I'll try checking the voltage out nd let you know what I find.
Hi, checked all power supplies to the rectifier, cleaned and replaced.
Then checked voltage from torch, One pic shows voltage on power setting one whilst trigger is pulled, the other pic shows it showing more voltage after trigger is released....
Then checked voltage from torch, One pic shows voltage on power setting one whilst trigger is pulled, the other pic shows it showing more voltage after trigger is released....
17.6v is on power setting one, this increases on each power setting increase.
What I don't understand is why there is an increase of voltage at the torch when trigger is released? Touching the torch to earth resets it back to 0.0v each time?
What I don't understand is why there is an increase of voltage at the torch when trigger is released? Touching the torch to earth resets it back to 0.0v each time?
A voltage remaining at the torch tip after releasing the trigger is normally caused by the smoothing capacitors not discharging. Touching the MIG wire to a workpiece makes a small spark and then the voltage drops to zero. There should be a bleeder resistor across the capacitors to avoid this slight problem.
However, I don't think that your machine has any smoothing capacitors !!
They would be cylinders, the size of an egg up to the size of a mug, added across the pos and neg welding output. Maybe someone has added capacitor(s), but I cannot see any from your pictures.
This thread has a circuit diagram for the Sealey SuperMig 170/1 :
https://www.mig-welding.co.uk/forum/threads/sealey-supermig-170-1-revamp-euro-torch-upgrade.49438/
It shows a 220nF 63v capacitor, but I'm not sure how that could increase and store the voltage.
What are the voltages at the tip at each of the 6 power settings? Has cleaning the connections at the rectifier improved the welding power? Does the power seem low at all 6 of the settings?
However, I don't think that your machine has any smoothing capacitors !!
They would be cylinders, the size of an egg up to the size of a mug, added across the pos and neg welding output. Maybe someone has added capacitor(s), but I cannot see any from your pictures.
This thread has a circuit diagram for the Sealey SuperMig 170/1 :
https://www.mig-welding.co.uk/forum/threads/sealey-supermig-170-1-revamp-euro-torch-upgrade.49438/
It shows a 220nF 63v capacitor, but I'm not sure how that could increase and store the voltage.
What are the voltages at the tip at each of the 6 power settings? Has cleaning the connections at the rectifier improved the welding power? Does the power seem low at all 6 of the settings?
This is the wiring diagram that Sealey fwd to me for my 170/1, I can't see any capacitors in this diagram so not sure what to do.
I'll check those voltages again, but on my preliminary check, they did increase with each change on the power setting.
I'll check those voltages again, but on my preliminary check, they did increase with each change on the power setting.
