SIP Migmate - trips out after a few seconds welding

[Karmann]

Hi, don't know if anyone can help but i'm having a few probems with my SIP Migmate welder.
Everything works fine but the unit has started to trip out after only a few seconds welding presumably due to overheating? It then takes a good 15-30 minutes before the unit will work again. I have slackened the tension on the wire in case this was causing the overheating but to no avail.
Has anyone experienced a similar problem or know what is at fault - i assume it to be either the transformer or wire feed motor? Are there any checks I can do to diagnose this and are parts still available?
The unit has old had mild usage and is in very good condition so don't really want to scrap it without at least trying to fix it!

Many thanks

Gordon

 

[the snooper]

its a bit of an odd thing but there are 2 possibilites that come straight to mind
1 the cutout has become faulty
2 the welding transformer is faulty and getting hot very quickly

take the side off weld until it cuts out dissconnect from the mains and feel how hot the welding transforer has become that should give some indication

 

[piman]

Hello Gordon,

does it have a fan and is that working?

Alec

 

[Karmann]

Thanks for the replies, I will take the side off the unit and have a go a welding to see how quickly the transformer gets hot and report back!
The welder is a SIP Handymig which i don't believe has a fan. Again i will check when i take the side panel off but don't recall ever hearing a fan running.

Thanks
Gordon

 

[Karmann]

Right, took the side off my welder and had a good look around. Was expecting it to be filthy dirty but all very clean and grime free. No fan in this model.

I've attached a picture and marked up 3 items to try and help explain!

I did a bit of welding on some scrap metal and very quickly the nut and bolt? that joins the various wires (No.1 on my drawing) got too hot to touch.

I kept on welding and after a few minutes the 2 transformers? (No.2 & 3) became very hot indeed.

Should they get hot after just a few minutes welding or should i be looking for a potential fault with the trip out switch? Out of interest can anyone point out which item the trip out switch is for me and advise whether these are still available?

Sorry for all the questions and thanks in advance for any help.

Gordon

 

[Robotstar5]

The bolted joint getting hot could be a high resistance connection, dismantle it (making a note of where everything is) and clean all the faces with a fine emery like wet & dry paper then re-assemble making sure it is tight.

 

[Karmann]

Had another look at my welder yesterday and as per Robostars suggestion, took apart the bolted connection and cleaned it up before re-assembly. Also blew out everything with an air gun just be be sure there was no dirt in the switches etc. Unfortunately all to no avail and still tripping out the units cut out.

The only thing I can think to do now is try replacing the trip out switch just in case this is faulty (seems to be a pretty cheap option) and if this fails I guess scrap it and buy a new welder!

Hope this isn't a silly question, but can anyone point out which component the trip out switch is? Is it on the control panel circuit board?

Many thanks

 

[Sub-arc]

I can't see too clearly from those pics. In my experience the thermostat is usually a small component on 2 fairly light wires and is stuffed inside or stuck to the windings of the main transformer. It can can normally be 'jiggled' out of this position. You might be able to trace it from the cut out light (if there is one)

I deffo wouldn't be thinking of scrapping the unit. Its spotless !
If you get over this problem think of putting a fan into it somewhere.

 

[Karmann]

Ok thanks Sub-Arc. No cut out light on this model but I shall have a go at tracing the cut out switch and look into the possibility of fitting some kind of fan.

 

[mike 109444]

Looking at the pic 2 the light blue and the red wire that go into the heat proof tubing and down to the main (big one!) transformer look to go to a black device stuck on the side of the transformer (just hidden behind some of the sleeving) If so this should be the cutout device. It can be bypassed with caution! (for test purposes only) If it is just faulty and tripping to soon then you would be able to weld for longer (still testing!) if it is not faulty then the transformer will start to cook!! Have someone watching the transformer for smoke. If you find you can weld for say 3 times longer without overheating then suspect the cutout.

 

[Wedg1e]

That looks very reminiscent of the HandyMiG MIGmate 90A thing I started with: it would thermal trip after a very short period and took 45 mins to cool down again.
I bolted a pair of ex-IBM mainframe PC fans (about 4" dia and 110v each, wired in series) to the outside of the case, over the louvres, and I think it cut out once in the rest of the time I owned it.

 

[R Kraft]

The duty cycle on the small welders is very low,usually 10-20% or so at full power.
20% is only 2 minutes of on cycle and a 8min cool down.
They really all need fans.
Robert

 

[Karmann]

Thanks again for all the help guys. i think i'll try carefully bypassing the thermal cut out for test purposes only an if this doesn't identify the problem then try and get myself some fans to keep it cool and improve the duty cycle. i think long term that a new better welder will be the answer as this i belive only goes down to 35A but hopefully it'll do me for a while.