Migmate 150 woes

Afternoon all, just signed up here having read a few useful bits and pieces, maybe some of you can help with my conundrum!

I bought a SIP Migmate 150 from that fateful auction site (I know, I know!) and although it has worked, I've had a few problems. When I bought it, it had a reel of rusty wire installed, so, a new reel and a new liner later, we were off. It welded - inasmuch as, it produced an arc which melted the wire and the workpiece. Not pretty but that's 99.9% me rather than anything else. I was taught MMA donkeys years ago, and used to be able to produce passable welds, but it's been a long time.

Fast forward: this weekend, the gas pipe sprung a leak, right near where it exits the body of the welder. Damnation - but one push-fit connector later, that was also sorted.

So, I set about the main reason I bought it - some welding on my Land Rover as MOT time approaches. Got started, did a few small spot welds to tack some pieces in place and then the wire motor just kept running, spooling wire all over the place. Took the torch apart, and there is nothing obviously causing the problem although the main thick cable back to the welder is showing signs of having overheated. At a guess, possibly that cable is worse inside the sheath somewhere and has shorted the wire motor cable? Maybe I'll get my meter out and try.

So (sorry for the War & Peace) here's my conundrum. Do I buy a new torch (£57 + P&P) and hope that cures it? Is the welder worth spending more money on? I don't want to throw good money after bad. Should I just buy something else? Everywhere I look screams "don't buy cheap/hobby welders" but on the other hand, I've got three small panels to weld on the Landie and then the welder is going to sit in the corner for heaven knows how long (probably until the next MOT!). I'm not going to be using this regularly, so an expensive unit doesn't make real sense. But I do want to do it myself rather than farming it out.

What do you suggest, ladies & gents?

these sips are terrible,even when brand new,so dont expect it to be like other migs you try...But,that one should be repaired without too much hassle if its a continuous feed issue,is the wire arcing when its spooling on its own?,I have spares from one i broke up if you need any bits,let me know.

Cappo said:

the wire motor just kept running, spooling wire all over the place. Took the torch apart, and there is nothing obviously causing the problem although the main thick cable back to the welder is showing signs of having overheated. At a guess, possibly that cable is worse inside the sheath somewhere and has shorted the wire motor cable? Maybe I'll get my meter out and try.

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trigger wire might be shorting out somewhere in the sheath or the spring steel trigger mechanism might be touching the valve block. both fairly easy to fix.
disconnect the trigger wire in the welder itself and if the wire feed stops you know your problem is in the lance.

its also possible one of the relays on the pcb may have stuck its contacts together.

So, I went back out to check whether the torch was live, as Gulf suggested. Peeled some of the rubber back from the cable at the torch end and there is a lot of damage on the main power cable, which looks like it has been shorting - it has even melted the plastic cover on the wire liner - suspect that's the problem.

So, Gulf, so you have a complete torch assemble for sale?

I have also noticed the problem which someone else mentioned on another thread where the wire speed seems to be fluctuating up and down on it's own. Don't think there has been a cure mentioned for that one yet!

Would the conclusion be then that it's worth spending £60 on a new torch (if Gulf doesn't have one) to resurrect this unit, rather than binning it?

I have a torch,but its not complete(cable and hose should be all there and ok though,rest is the trigger switch etc,all slots together),Ill have a look and get back to you.

Thanks!

Don't just look at the torch, disconnect the thin blue torch trigger wire at wire feed end of the torch, if the wire still runs when you switch on it's the power relay inside. You will find pictures on the forum showing burn relays they have a nice black finish on the inside new relay.

migmug said:

Don't just look at the torch, disconnect the thin blue torch trigger wire at wire feed end of the torch, if the wire still runs when you switch on it's the power relay inside. You will find pictures on the forum showing burn relays they have a nice black finish on the inside new relay.

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Hmm, as above, last night it was working OK again. A sticky relay, perhaps? Are these easy to get hold of (replacements)?

Look at the relay for the Black deposit on the inside of the platic cover.

You can get replacements, but check which version one you have,

PCB mounted mounted relay version, Original is 16A single pole normaly open(SPNO) you can use single pole change over (SPCO) you just chop off the normaly closed legs on the relay, can get from MAPLIN ,FARNELL, CPC or try SIP.

Non PCB mounted like my Autoplus 150 FINDER RELAY model 6531, sip code was 10005 Maplin don't do them could try FARNELL,CPC.

You could try RS if you Know someone with an RS account.

This is a pic of the type of relay I use at work. It is very similar to the type found in some migs. You might just make out to the right of the "R" in the word Finder where there is some soot on the inside of the cover. This comes from the spark that can be generated when the contacts open. The sparking will eventually burn the contacts and cause 1) intermittent operation or 2) no power across the relay even though the contacts are closing or 3) the contacts may weld themselves together (intermittent like you have or permanently).
A TEMPORARY fix is to remove the cover and clean/file the contacts but a new relay should be fitted asap.
The details for a replacement that you need is on the cover "TYPE 40.52" If you struggle to get correct TYPE then the other info on the case can be used. In the case of the relay shown it's the "8A 240v" that tells you it can switch an 8amp load at 240vAC and the 24v DC markings refer to the voltage needed by the coil in the relay to make it switch.

Just had a quick look on ebay and there a quite a few (thousand ) but note those that are marked as "24v" maybe for switching 24v not 240! So use your TYPE number when looking.
If not sure come back and post link to what you think might be right

Thanks Mike, I had a look at mine and there's a small amount of soot, and when you operate it there's a bit of an arc across the relay contacts. Took the top off and cleaned it but as you say it'll probably need replacing.

I failed to write it down but I think the relay said 40.61 and not 40.52, I'll have to have another look, but it's the same make and colour as the picture you posted.

Either the relay overheated or the cabling shorted (favourite diagnosis as there is a lot of burnt insulation on the main cable). The machine is working again but I doubt it will last long. Gulf is looking a spare torch out for me at the moment.

Note the pic I posted was from the machines I service and test. They are medical machines and not welders! the power the relays switch is lower hence the 8Amp rating where as the one you need will be rated at 16Amp but will look almost identical apart from the numbers.
ps would not want to put a welder where the medical device goes

Dunno if anyone has mentioned it, but with a mig its really important to get a good earth. Make sure your clamp is shiney as well as the weld metal surface it clamps on to. Bung a small bundle (the size of a 50p) of copper wire in there to make the surface area contact a greater surface for the earth.