Help, problem with my mig

[Blaserman]

Hi Guys
Appoligies that my first post is for help.
I have a Cebora mercury 160 which has had very little use, about 12 months ago it started playing up. The problem was the wire remaining live and the gas still flowing from the nozzle after the trigger has been released. This problem rectified itself until today that is. It also doesn't appear to be welding properly i.e not penetrating (if thats the right term) the steel I am welding. I am using argoshield as the gas. Can anyone shed any light on what may be wrong with it?
Thankyou in advance.
Rob

 

[the snooper]

it would be worth checking the relay on the pcb as it could be arking / sticking hence the poor weld and live torch. they are easy to replace

 

[Blaserman]

Thank you for the quick reply. I am afraid its back to basics for me though! Where do I find this relay? How do I check it? PCB? printed circuit board?

 

[the snooper]

yeah printed circuit board some are part of the wire feed control assembly and you will find it there although not guaranteed some have clear plastic covers so you should be able to see if there are any traces of burning

 

[NotANormalCoder]

Not 100% on this, but most smaller Cebora sets have a white plastic relay mounted on the PCB (behind wire speed knob) with 2 0.25" terminal spades with heavy(ish) wires connected. This control welding current on/off and it usually fails totally for the reasons noted above.
However, you complain of low power and poor penetration - assuming good earth connection and gas flow, follow the earth lead inside the machine and check where it joins wires from the transformer/rectifier. The earth usually connects with a 6mm bolt to these wires and the connection is covered by heatshrink tube. Cut this off and check for arced or broken wires. Reinsulate with tape after.
Also, check recifier (large ali plates sandwiched together) as connections break/arc. Also, tighten vertical bolt(s) that hold it all together, as these work loose and cause poor contact between internal connections.
Finally, if not cured, look sideways between rectifier plates and check every individual diode - small black things pressed into plates. Each one has a small wire that connects it to another plate. If any of these wires are burned or broken, then you need a new rectifier - sorry.
Post pictures of inside if you are unsure of components and ALWAYS disconnect from mains before removing covers.
Dave

 

[Blaserman]

Took the cover off when I got home from work, there is a white relay no clear lid though worse luck. There is no marking on the outside but I have ordered one to replace it, hopefully it will do the trick. Thanks for your help