Mig welder up the spout. Help!

[chunkolini]

Its a Butters AMT 180.
Ive been running it on 13amp fuses for over ten years.
Today it started blowing fuses. Turn it on, press the button and blown fuse.
I know less than nothing about electrics. Anybody got a clue what it might be?

 

[Spark plug]

It could be one of many things, but first of all I would have the cover off and look for anything obvious. Things like a broken wire, signs of burning/arcing etc.

Dose it blow the fuse on all voltage settings? Is the fan working as unlikely in your case but I've known these to cause problems?

 

[normspanners]

do you have an rcd on your supply ?
ie either on each circuit mcbo's or just one on main switch on your consumer unit?

 

[WorkshopChris]

As above covers off and have a look does it hum extra loud when you pull the trigger and the fuse blows, also do you you have a rdc on the supply?

 

[the snooper]

If you pull trigger and it blows fuses could be a failed 240 v contactor or as touched upon already if it buzzes badly a failed rectifier

 

[normspanners]

If it blows immediately it could be grinding dust in DP contactor making the trip across the two contacts but usually once blown, it zaps the dust unless it has carbon'ed up and has made permanent track

 

[chunkolini]

Its on an extension lead, once it blew the fuse at the mains end of the lead, otherwise the fuse on the plug.
It sounds fine when i turn it on. Fan is ok, no buzzing or anything untoward.
Press the button and I hear gas flow then the fuse goes. Not touching wire to workpiece.

 

[bletchmonster]

Anything is a long shot with that sort of symptom, check for swarf stuck in it's undies. A bit stuck to the side of the main transformer shorting the coil to the laminate iron caused mine to do the same thing. Pulled out the swarf and it's worked fine ever since.

 

[chunkolini]

Well.
I tried it straight from the mains socket with a different torch and tge case open.
POP!! And a spark from by the blue lollipop thingy (technical language is improving here) and plentiful profanity. But i hear the fan running. It also seems to work again.
No sign of ill effects.
Weird; coffee and loud music time
Any body got an idea? Swarf or dust allowing it to short?

 

[Spark plug]

Could you post a pick of the blue lollipop thingy to help borrow it down a bit?


Have you had a chat with it, it may just be sick of welding fish

 

[chunkolini]

Blue lollipop thingy

 

[chunkolini]

Working fine now.
Maybe the workshop monkey telling me to clean my welder out now and again.
Thanks for speedy attention.

 

[Spark plug]

Those connections near the blue lollipop thingy don't appear to be tight, but it may just be the angle of the pic, worth checking.

 

[tflnemesis]

Blue lollipop thingy looks like a capacitor if it went pop it might be damaged, might be worth sourcing a new one.

 

[MattH]

More likely it's a thermister used for inrush current limiting or back EMF suppression.
Could of gone open circuit allowing to high of an inrush current thereby popping the fuse.

 

[WorkshopChris]

is it the diodes on the way our what is the shadow i can see ( blast damage?)on the 2nd aluminium plate top left?

 

[gordon stephenson]

If all else fails Chunko, Carl Horton used to work for Butters, He has been in business as " Horton welding supplies " for a few years now, He sorted out my Butters problem over the phone, Really nice guy and very helpful.

 

[normspanners]

some lollipop thingys are crowbar capacitors or resistors so if there is a lighting strike it goes short to blow the fuse and stop you from being zapped things like quality welders roller shutter doors etc have them if you load them too much they eventually go open circuit and the thing seems to repair itself but there is now no protection, because you have blown it open circuit, was there any lighting around ?.

 

[chunkolini]

Thanks for the information chaps; I will have a good look on Monday and report back.

 

[Jim Davey]

I think if you look between the aluminium plates of the rectifier you are going to find at least one press fit diode with its leg (wire) blown off.