Pro 90 mig problem

[big-wayne]

Hi guys
New to this site so forgive me if this has been covered in another post but I have got a problem with my pro 90 mig.
I have had this welder for about 20 years (yes thats right 20 years) bought it when i left school when i was training to be a motorcycle mechanic and have used it loads over the years until recently.
started welding some steps for my perants caravan and just couldn't get the weld right thought it was me at first then the feed kept stopping and the filler wire started glowing and there was a humming noise, couldn't get it to arc up properly to melt the wire. the feed motor runs ok until you ground the electrode wire.
I have changed the liner, the electrode tip and gas shroud. I have also put a new spool of wire on just in case the wire was coroded but still the same.

Would be greatfull for any replies feels like ive lost an old friend

Cheers

 

[mike 109444]

It might be worth replacing the relay on the pcb for what it will cost. I think you are looking more at a problem with the diode pack or the main transformer as I think it feeds power to the wire motor as well as the welding voltage.

 

[mike 109444]

ps might be worth checking your work earth clamp and lead as these do breakdown over time. (you could temp for testing bypass using a car jump lead)

 

[optima21]

I had issues with mine a few years ago, it turned out to be a bad connection between the output of the transformer and the earth lead from memory, it was also the earth of the pcb which lead me to thinking that trhe pcb had died. when the connection was taken appart and rebuit it worked fine

 

[the snooper]

if its buzzing badly I would be checking the rectifier sounds a likely cause