Hi all, I have a problem!

[dan.taylor.1]

Bill, have you had the side panels off and had a look for any loose connections aor faulty components (with it unplugged obviously) if you pm me your email I'll send you the manual as I've the same machine (think you've commented on my post with the same issue??)

 

[Questions]

8 volts seems low, but if the welder goes down to 20 amps then may be its ok.
Check polarity, ensure you have it right for the wire your using, DCEN for ordinary solid
mig wire, and DCEP for flux cored wire.
As mentioned, take off the panels with the power off, and have a look for loose connections.
Ensure all wires are tight, even swap over the mig gun for another just to rule out problems with it.
You could even send an email to the manufacturer explaining the symptoms, they may have come across
this issue before.
Try stick welding with the leads swapped around, from where you previously tried them, it could be an earth
problem, loose wire inside the welder.
But if your not comfortable with being inside the welder, then get someone who is to have a look around.

 

[dan.taylor.1]

It's meant to have a low of 12 and a high of 28 according to the manual so not too far off.

 

[Bill Harrison]

Thanks for getting back to me.
I dont know if it makes any difference but my set is Inverter based.
In Stick mode it is a 250 Amp set but in Mig it is 200 Amp.
Unfortunately I bought the machine some 7 or 8 years ago, all be it was only 2 or 3 months old at the time and I can honestly say it hasnt done a weeks worth of work in all the time I have owned it.
It has usually performed very well once it has initiated an arc but when I think back it has always had some sort of problem striking up but I have always blamed it on myself or some other factor over which I have control and never suspected the machine however now I cant get it to weld for more than a few seconds (If at all) before it sticks in the tip.

I have spoken to Newarc tech and they inform me that they probably wouldnt be allowed to work on it because of its age and if they were it would be £45/hr but they dont have any spares either.

I am just a bloke at home in his garage who had a bit of money one day and decided to spend it on a quality piece of kit believing it would never go wrong....I bet if I had stuck to the usual import junk it would have lasted longer than this.

Unless I pull a rabbit out of the bag it looks like I have me an £800 tool trolley that looks suspisciously like a gutted welder!

 

[Bill Harrison]

It's meant to have a low of 12 and a high of 28 according to the manual so not too far off.

It's meant to have a low of 12 and a high of 28 according to the manual so not too far off.

Hi Dan, thanks for the input.

I have never had any sort of manual with this machine, I dont suppose you have it on pdf or ANY other info?

 

[Bill Harrison]

Bill, have you had the side panels off and had a look for any loose connections aor faulty components (with it unplugged obviously) if you pm me your email I'll send you the manual as I've the same machine (think you've commented on my post with the same issue??)

Hi Dan thanks for the reply, I cant figure how to PM you, sorry I am not too genned up on forums and how they work.

 

[Bill Harrison]

Bill, have you had the side panels off and had a look for any loose connections aor faulty components (with it unplugged obviously) if you pm me your email I'll send you the manual as I've the same machine (think you've commented on my post with the same issue??)

Yeah mate, I've got the panels off and had a real good poke around, I'm a spark by trade so not scared of being in there but dont let that make you think I know it all, if you have any ideas shout em out, I aint too proud to ask for help.

 

[Rig Pig]

From what I've seen inverter sets are a nightmare to fault find on, you may gain a bit of inspiration watching a few YouTube videos on repairs to CUT type plasma sets, they are inverter based machines, it seems to be something to do with going from CC to CV as the stick side works ok but I'm a rig mechanic and a bit out of my depth on switching power supplies I'm afraid. You could try @Jim Davey

 

[Seadog]

I cant figure how to PM you

Click on his name and select the 'start a converstion' tab.

 

[Bill Harrison]

8 volts seems low, but if the welder goes down to 20 amps then may be its ok.
Check polarity, ensure you have it right for the wire your using, DCEN for ordinary solid
mig wire, and DCEP for flux cored wire.
As mentioned, take off the panels with the power off, and have a look for loose connections.
Ensure all wires are tight, even swap over the mig gun for another just to rule out problems with it.
You could even send an email to the manufacturer explaining the symptoms, they may have come across
this issue before.
Try stick welding with the leads swapped around, from where you previously tried them, it could be an earth
problem, loose wire inside the welder.
But if your not comfortable with being inside the welder, then get someone who is to have a look around.

I have the sides off and have blown it out and had a real good nosey around, I am a spark by trade so being in here doesnt worry me, but please dont let that make you think I know it all, I have asked for help and only a fool would then refuse to hear others ideas.

Re Polarity, my torch is permanently on the Positive side of the set, it cant be moved anywhere else without a fair bit of dismantling the machine, so as far as Mig goes I only have DCEP.
On the other hand in Stick mode it is possible to reverse the leads and get DCEN or DCEP.

I have swapped torches and nothing changed.

I have spoken to the manufacturer and they are scratching their heads but will only look at it for £45/hr!

 

[Bill Harrison]

From what I've seen inverter sets are a nightmare to fault find on, you may gain a bit of inspiration watching a few YouTube videos on repairs to CUT type plasma sets, they are inverter based machines, it seems to be something to do with going from CC to CV as the stick side works ok but I'm a rig mechanic and a bit out of my depth on switching power supplies I'm afraid. You could try @Jim Davey

Thanks for that, who is @Jim Davey?

 

[eddie49]

It is definitely worth trying the suggestions from Dan and "Questions" about opening the covers and checking all the internal connections. Look for loose, corroded, or burnt connections - especially at push-on flat blades. Make sure that the machine is unplugged from the mains, and has been off for some time. Inverter machines have capacitors which will be charged to 325v DC and can hold that charge even when off.

The machine works correctly in stick ( constant current ) mode, so the basic power components must be working OK. I guess that something is wrong with the control logic for MIG welding ( constant voltage ). The measured voltage rising to 40v whilst burning back to the tip may be due to feedback control, trying to get enough current flowing, There may be a current-measuring shunt ( a heavy-duty low-value resistor ) in the circuit.

Instead of trying to weld, you could try this test: make a modest load by wiring three 12v 60W car headlamp bulbs in series. Connect them between the torch tip and the earth clamp. Measure the DC voltage across this load, whilst turning up the power control, it should rise smoothly from 8v to 30v.

 

[Bill Harrison]

It is definitely worth trying the suggestions from Dan and "Questions" about opening the covers and checking all the internal connections. Look for loose, corroded, or burnt connections - especially at push-on flat blades. Make sure that the machine is unplugged from the mains, and has been off for some time. Inverter machines have capacitors which will be charged to 325v DC and can hold that charge even when off.

The machine works correctly in stick ( constant current ) mode, so the basic power components must be working OK. I guess that something is wrong with the control logic for MIG welding ( constant voltage ). The measured voltage rising to 40v whilst burning back to the tip may be due to feedback control, trying to get enough current flowing, There may be a current-measuring shunt ( a heavy-duty low-value resistor ) in the circuit.

Instead of trying to weld, you could try this test: make a modest load by wiring three 12v 60W car headlamp bulbs in series. Connect them between the torch tip and the earth clamp. Measure the DC voltage across this load, whilst turning up the power control, it should rise smoothly from 8v to 30v.

Thanks for youre response, I will rig up the test as you described and get back to the thread with the results.

 

[Rig Pig]

Thanks for that, who is @Jim Davey?

He is a forum members who owns a shop selling welders and consumables, he also repairs welders and is quite likely to know something about these machines.

 

[eddie49]

These guys ( formerly Farnell/Gould/Advance switch-mode power supply designers ) repair inverters:
http://www.advanceproductservices.co.uk/index.html

 

[Seadog]

That's very interesting. Advance started just a few hundred yards from where I was born, and I had a couple of friends who worked at Advance in the early 70s. I didn't realise the name was still going.

 

[Shedendman]

Ok,my two tupence worth,long shot i know
When i had this problem of the wire at the tip glowing red i found out the the outer case of the wire feed motor was earthing itself out against the case of the welder just by a tiny wear mark,i stuck a bit of tape over the scratch and bingo all was good
Like i said,long shot,but you never know

 

[Jim Davey]

I can probably get to the bottom of this with a short phone call. Give me a ring after 9:00 tomorrow and I’ll happily talk you through a few steps towards finding the fault with a bit of luck. 07775674031

 

[Bill Harrison]

I can probably get to the bottom of this with a short phone call. Give me a ring after 9:00 tomorrow and I’ll happily talk you through a few steps towards finding the fault with a bit of luck. 07775674031

Thankyou so much, I will call you in the morning.

 

[Bill Harrison]

The problem happens at all wire speeds and voltage settings.
It used to be intermittent and I generally blamed myself for poor technique or set up but I think I was being unfair on myself now because the problem is permanent.

I have rigged a DC motor and a light bulb in series with each other and connected them across the Ground/Negative lead and the contact tip of the torch and then put a DC volt meter across these terminals as well.
When I hit the trigger the meter starts at 8v when voltage setting is at lowest and then it rises nice and steady to 29v as I wind the voltage control over to maximum.
Altering the Wirespeed/Current makes no difference to these results, but I dont think it is meant to.

In short the set seems to be doing everything that it should EXCEPT weld!