Have I killed it?

[Phaeton]

Had a Clarke 90EN for a couple of years, not a very good welder (me not it) but I get along & manage to stick pieces of metal together. Always used it with the fluxed wire, but on Christmas eve knowing I needed some wire I mistakenly bought some 'proper' wire. Actually ran out today but wanted to do some more welding, a friend of mine has a CO2 bottle, so off I went to fetch it, connects it up & for the first 5 minutes very impressed, welding seemed to be easier, felt like more control, less splatter & they looked better, then it all fell apart.

What I hadn't done initially but did do after a couple of minutes was turn the cables over, so + became - & - became + like it says on the front of the welder. All that happens now is that the wire glows red hot & melts but doesn't arc up. Even on full power it's not possible to weld with it.

Have I killed it? It did have a new rectifier/regulator not long after I got it as that burnt out, the new one was a lot heavier.

Alan...

 

[rtbcomp]

Is the wire till feeding? Have you tried swapping the wires back? Are the connections good and tight, including the earth clamp on the workpiece?

 

[Phaeton]

Wire is still feeding smoothly, increases if you turn up the feed. Having the wires on either way round makes no difference, pretty sure all connections are good, tried a couple of pieces the one I was welding when it failed & some scrap when trying to resolve problem so I thin kthe earth/return should be good.

Alan...

 

[chrisg3103]

id be interested in the answer to this, mine started doing this a while ago (90EN) so i swore at it a bit threw it in a corner and got another welder if theres a fix then i can get it working again

 

[R Kraft]

At a guess.
It sounds like you have lost a diode or two in the rectifier.
Shielding gas changes the amps volts parameters and may have made the parts run hotter.
Do you have a volt meter, and are you even a little technical ?

 

[Phaeton]

Do you have a volt meter, and are you even a little technical ?

Thanks for the reply, yes to volt meter, I am a little technical as long as the idiot guide is idiot proof.

EDIT:- There is a wiring diagram HERE if that would help on page 12.

Alan...

 

[R Kraft]

The diagram shows a center tapped transformer type supply.
So you should have about 24vac across the transformers low voltage leads or about 12vac center to outsides.

Putting larger diodes in would help the surge capability of the supply.
But the thing has no fan so the larger diodes would overheat just about like the smaller ones.
So I would say that one of the diodes has gone away and you only have about 8-9 volts to the gun.

The overtemp switch is also suspect, if your is on the rectifier.

If you replace the diode/diodes and put a box fan

over a vent to keep things cool.
You should be back in business.

 

[R Kraft]

I forgot to mention.
The transformer wires on many of the little welders,bolt onto the aluminum rectifier fins.
Aluminum connections are notorious for heating, oxidizing and not conducting.
So you might try checking the rectifier connections first.

 

[Phaeton]

Thanks again Robert for the reply but all you said went straight over my head other than I should be looking for 24vac or 12vac. As I said I really need an idiot guide i.e. put + probe on A put - probe on B you should get x, put + probe on A put - probe on B you should get y. Also being truly thick I wouldn't know a diode if it jumped up & smacked me n the mouth, but am willing to learn if you have the patience.

Alan...

 

[paultic]

i had this problem with mines not too long ago
a little bit off splatter had managed to fall in through the tip
had the glowing wire with no arc
took off the tip gave it good clean, gave the wand a little bang on the floor
then sorted might be worth a try

 

[Gas mark 5]

I had that with mine a while ago, that was just a load of gunk in the shield, shorting it out, same as paultic. Be worth checking that before anything else

I think that this is the sort of diode you find in welders, but more than that i don't know

george

edit: By the way, I don't think they like one continually trying to use them if they are going like that, that was the only time my thermal cut out thingy actually cut out

 

[R Kraft]

I suppose the first thing to do would be to release the wire drive and measure the DC voltage,between the tip (take off the shroud/nozzle) and ground.
It should be at least 20 volts and maybe as much as 35.
Sorry about the login name change,the site won't let me log on.
Robert

 

[Phaeton]

Once again thanks to everybody who replied, I appear to have cured the problem but not sure how. I took off the side & was completely confused as to what was in there, if I'd have had my camera I would have taken a picture for somebody to explain. Looked like 2 sets of windings & a big aluminum fin shaped thing, with wires attached. Anyway thought I'd get some results for Robert so removed the wire & meter'd across tip & earth strap. I have 4 settings 1 Min/Max & 2 Min/Max on 2 Max I initially got 27.4 volts I then pressed again & this time only got 18.5 volts which then started slowly dropping I gave up at 13.2 volts. I tested the other settings again with what appeared to be poor results & dropping voltage. I then disconnected the + & - cleaned them up, filed the crocodile - strap, changed the tip & cleaned out the nozzle, although there was little in there. Tried the meter again & got a constant 27.4 volts, re-threaded the wire & I have a welder again.

Thank you everybody that helped you've saved me some money, well for the time being at least.

Alan...

 

[R Kraft]

Glad you got it working !

I've had a big stick welder but I always wanted a mig welder.
As soon as I bought one I ended up with two more that had minor things wrong with them.
Then I swapped some work for a big strange one.
If the wind will go down and warm up, I want to see what it will do.
Regards
Robert