Welding issue for a newbie

[George JervisParticipant @georgejervis86082]

Hi everyone, 

A bit off topic

While doing a job this week using my late dads mig welder 150 turbo. I could only manage about 6 or 8 tack welds before it stopped working, my father had no issues with . the fan was still running but the wire stopped feeding and striking up. Could this be a thermo cut out switch? It used to work very well last year but now it’s frustrating to use.
If it is a thermo cut out switch where would it likey be situated in the welder? I’ve opened it up but can’t see one. 
Any thought and help would be appreciated
Thank 
George

[George JervisParticipant @georgejervis86082]

Welding issue for a newbie

[FMESParticipant @fmes]

Have you by any chance stuck the welding wire to the feed nozzle?

Get a pair of pliars and pull the wire off the end.

Sometimes this happens and the feed stops, but the actual feed motor is still running with the feed roller slipping on the wire.

Regards

[George JervisParticipant @georgejervis86082]

Hi
I thought of that first but no it was clear the feed motor doesn’t run when it stops. It’s like the whole welder is turn off but the cooling fan is still running . The cooling fan normally runs when I turn the welder on which I think is normal?
George

[John RuddParticipant @johnrudd16576]

Looking at the schematics, the thermal switch is an integral part of the transformer…but main power is switched via a relay mounted on the circuit board… The relay is activated by the switch built into the torch….

So is the switch working ok, can you here the relay operate?….

[Mark RandParticipant @markrand96270]

It won't hurt to take the cover off and check all the connections. Some of them tend to be pretty crude in the low end MIG welders. DAMHIKT!

[George JervisParticipant @georgejervis86082]

Hi,
Theirs no clicking sounds of a relay at all it like the welder is switched off but the cooling fan is running. I’ll check all the connections tomorrow hopefully.
Sorry to ask a Silly question if the connections are corroded when I turn the welder off and leave it for a while and then turn it back on why does it work for a while?
George

[Mark RandParticipant @markrand96270]

Thermal switch could have degraded to the point where it's cutting out at too low a temperature. Farnell will probably have a replacement. Look for the approx 1/2" round device with two spade connectors stuck/clamped to the transformer. It's still worth checking all of the contacts. I assume it's been transported, most of the contacts will be spade connectors or nuts and bolts around bent copper/aluminium. It's surprising how intermittent they can get.

[charadamParticipant @charadam]

I wonder if it's anything to do with the (alleged) heatwave?

[HopperParticipant @hopper]

Posted by charadam on 12/08/2018 00:49:43:

I wonder if it's anything to do with the (alleged) heatwave?

Do what we do here in the tropics and stand a desk fan next to the welder to give extra cooling.

[Speedy Builder5Participant @speedybuilder5]

Are you using it at max current setting? Try a lower setting and see if it makes a difference ??

[George JervisParticipant @georgejervis86082]

Hi,
I was making a 10ft by 4ft metal trellis welding 6mm bar. The welder settings was halfway as I always leave it on that and the weather wasn’t extreme like it has been. I forgot to mention the gas still comes out the nozzle when you pull the trigger but I think this is a separate item. I think I’ve put a few pictures up in my album if I’ve done it right showing the inside of my
thank you for the help so
George

[Nicholas FarrParticipant @nicholasfarr14254]

Hi George, it is quite common for a simple valve in the torch opened by the trigger to allow the gas to flow. However, in your second photo, it looks as if there is a piece of silver foil under the fuse on the circuit board, if so this ought to be removed and a replacement fuse of the correct value to be put in. I had and issue with my small MIG welder which was similar to yours and mine was as simple as the transformer on the circuit board failing.

It was replaced with one that I had, but I had to mount it off the board.

I would check that out as a starter first.

Regards Nick.

[George JervisParticipant @georgejervis86082]

Hi everyone,
Well I’ve had a good look tonight at the internal parts of my mig welder and put some more pictures in my albums, I still can not see or make out the thermal switch???
I have removed the circuit board which controls the wire feed? The blown fuse looks like a 2amp one. Looking at the board the transformer which I’ve pictured on the board looks like it’s arcing or burning inside? Looks very sooty would anyone be able to point me to where I might get a replacement or how to fix it
Many thanks
George

[Nicholas FarrParticipant @nicholasfarr14254]

Hi George, I doubt very much you will be able to fix the transformer if it has failed, all you will be able to do is replace it, but you will need to know the output voltage and current. You could try someone like **LINK** or **LINK** for a replacement that would be suitable.

Regards Nick.

[Martin WParticipant @martinw]

Hi

I can't see a damaged transformer in your latest pictures, however there is a relay that has contacts which are showing some signs of distress and this has blackened the clear plastic case above them, normally caused by contact arcing. It may be worthwhile removing the relay case and try to clean the contacts. Contact cleaning tools are or were readily available and normally have a thin blade that has diamond dust or similar impregnated in it. Used to be used for cleaning contact breaker contacts on cars.

May improve things but there again mat do nothing but worth a try and its easy to do. Power disconnected of course.

Cheers Martin

PS

Judging by the pictures the fuse looks to have been subject to serious over current when it blew. The fuse link, copper wire, has a wide rupture gap and there is melt back of this link. It would be interesting to see if a replacement fuse suffered the same fate, if so that may be why some idiot used aluminium foil as a replacement be it a stop gap measure or not.

Edited By Martin W on 12/08/2018 19:31:39

[George JervisParticipant @georgejervis86082]

Hi Martin,
Thank you for the advice on cleaning the relay with a fine diamond fill. I have done that and today I have used the welder for a Solid 2 hours welding various metals and it has not cut out once where was before it would have cut out within 10 minutes of its first use. Unfortunately I could only find a 3 amp fuse of the size to fit so I put that in as a temporary measure whilst I get the 2amp one.it would be interesting to see if the 2 amp fuse blows simular to the old one in the future? I’m not saying it’s fixed by any means but it’s working at the moment.
A big thank you to everyone that gave their time and advise for me 😁

George

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