Clarke 105EN losing power as it gets hotter?

[zxr400]

Hi All,

Excuse the mammoth post

Recently my 105EN has started going off the boil.... The standard earth clamp was looking tired, so I bought a nice clamp from Weldequip and fitted it today, and gave it a try:

On 1mm mild steel sheet, on gas (definate flow of gas), started with max setting (2, Max) blew a hole through, no probs. On 1 Max, Was popping as if wire feed was out (usually 5-6). Tried with the 1 and 2 min power settings, same popping, not sustaining an arc.

Next I adjusted the wire feed with one hand whilst welding with the other.... got down to speed 3 on the dial, and got a nice arc on the two higher settings, but got a fairly poor arc on the min settings.

No real penetration on the lowest settings, I would describe the welds as 'cold'. The higher two settings would weld ok, but penetration was way down on what the welder is capable of. Even on max settings, it's struggling to penetrate 1mm sheet. I noticed that the weld would get poorer in the last minute before the thermal cut off came on.

Basically, anything over 3 on the feed dial, and it won't sustain an arc, just pops and burns the wire back. At feed setting of 3 welds ok on higher settings, but is down on power. The lower power settings are ok from cold, but as the welder warms up, the arc won't sustain, even at 3 on the feed dial.

I've changed the earth clamp, wire feed is working well, gas is flowing ok and wire is clean. Nothing looks burnt out inside, and the welder is nice and clean inside. The earth clamp was stone cold when removed from the steel after welding, which makes me think it's not an earth problem, else I'd expect it to be hot.

Wish I'd checked the voltages for each power now, but ran out of time tonight.

Any ideas?

Cheers,

Mark.

 

[Rot Box]

I had the same problem with my Sealey Migmate. The first thing I did was dismantle and clean all the connections to the transformer. To keep the welder cool I tend to make sure it's only switched on when I am actually welding. As it's a pre-turbo model I plan to fit a 12v transformer running couple of 12cm computer fans as well to increase the duty cycle.

 

[the snooper]

do you get any smell from the welder as the quality of weld drops off ?

 

[zxr400]

Hi Snooper/Rot Box,

This is a turbo mig, so its actively cooled. Must say that even at full power, the duty cycle is respectable, and unless you're going for it, the cut out seldom comes on. I can highly recommend using a fan.

No. no smell, nothing seemed excessively hot inside. Transformer windings look healthy from what I can see, as does the pcb. It sounds like a bad connection, faulty diode, or insulation breakdown as the unit gets hotter.

Bit of a strange one, really. As you suggest, I think I'll have to check the transformer connections, torch connection, and the inner connections for the din plugs.

Cheers,

Mark

 

[the snooper]

if the thermal cut out kicks in then the transformer its mounted on must be getting too hot.
you could always test the resistance of the transformer when cold and again when its cut out it may give you an idea.
as you said above check all connection then if no better the tranasformer may be on the way out

 

[stormin]

Heat in a wire coil will reduce it's capacity to flow electrons, build resistance and further decrease power.
If you've got a faulty transformer were some of the insulation on the windings has broken down this will lead to low power from the outset and quicker heat build up. Repeatedly overheating it will worsen the problem.
If you can find the resistance values for the original specification or take them from a newer undamaged machine and compare them to yours it may show if the coils are faulty.
If you want to try and repair it, it may be possible to rewind the coils yourself even using the same copper wire with new laquer insulation if the wire itself hasn't burned out.

 

[zxr400]

Just a quick thought, could CO2 be my problem? I've read a few posts about voltages being lower on C02, and on thin metal, having to turn the feed right down in order to get an arc. If the lowest two settings are too low, and the two max settings are lower than they should be, to my mind as the transformer heats up and the internal resistance increases the voltages will drop further, compounding the problem.

It seems to support what's happening, but just wondered if anyone had any thought on it? I'm on 0.8mm wire, welding 1mm Mild Steel.

Can't do any physical checks until the weekend, so just thinking out loud in the meantime

Is it worth a disposable bottle of Argon mix to find out?

Cheers,

Mark.

 

[weldequip]

Just a quick thought, could CO2 be my problem?

Very likely yes. Stick it on Argonmix gas with 0.6mm wire and you should see a marked improvement

 

[zxr400]

That sounds like a good plan!

I'll check connections and voltages, and if nothing is amiss I'll go ahead and give it a blast. Will I have to up the wire speed and/or slow down torch speed with 0.6 over 0.8? As I'll be putting down less material with the 0.6...

Cheers,

Mark.

P.S.. Sif Autoshield is spot on - Thanks again

 

[zxr400]

Very likely yes. Stick it on Argonmix gas with 0.6mm wire and you should see a marked improvement

Well, you were very correct! Even just changing to Argonmix has totally transformed the welder. The 0.6mm wire definately helps on thin stuff, although I think I'll need to experiment a little to find a good torch speed to put down enough metal.

I was inspired by a murex 230, which welded so beautifully... It made me go out and buy some Argonmix to get my welder sorted.

Thanks all for your help and advice.

Cheers,

Mark