Sureweld Monomig voltage

[scotto75]

Hi all,

Just run some voltage tests on an old Sureweld Monomig 101 I've got hold of that was given to me as an unknown quantity, and I'm not certain if this is correct. It has four settings....

Min 1 - 20V
Min 2 - 26V
Max 1 - 22V
Max 2 - 24V

My basic understanding is that I should still see a proportionate change in voltage from the lowest to the highest even when measuring without an arc?

I know the voltage drops when it arcs, so would it better to check the voltage when welding to get an accurate reading on the the four different settings?

What voltage readings should I expect roughly?

 

[PTvor]

See this thread

http://www.mig-welding.co.uk/forum/threads/murex-tradesmig-160.55709/page-2

That looks about right, measured with no load.

Bear in mind that your Sureweld may not have any smoothing capacitors and so you won't be measuring a steady DC. Also, your meter will probably produce some sort of average which won't be RMS, because it will have been calibrated for a sine wave and so on.

Under the sort of load the welder is designed to deliver, I'd expect to measure roughly 0.7 of those figures, although the waveform would be really messy as sometimes there would be shorting of the arc and sometimes arcing. What does it say on the data plate or in the manual?

If you are wondering whether it's worth trying with wire and gas, I'd say yes, as long as there are no other obvious problems, such as the wire feed not working.

 

[scotto75]

Thanks PTvor for taking the time to reply.

Don't have a manual unfortunately, although I don't imagine it'd have much info. All I have is the data off the front panel. My readings seem to fit within the Nominal voltage range displayed.

The readings did fluctuate whilst I was taking them, but didn't know if it was an issue that the reading for the highest of the MIN settings - 26V - was higher than both the MAX readings? I had only imagined there would be a slight increase in voltage as the settings increased, similar to the readings in the thread you linked to.

There's no issue with the wire feed, apart from the wire being 0.8mm and the feed wheel being on 0.6mm, but I turned it round so it is in the larger groove and that worked better.

I was a bit concerned when I turned it on and didn't hear a fan, but opening it up I can see that there isn't a fan, so no issue there!

The is a fault with the torch, which leaks gas. The regulator is the cheapest bit of tat I've ever seen, but I can get 10lm on the peashooter when opened up full. However, even when the machine's not on I can feel gas coming out of the white block housing the valve/solenoid, where the pipe enters. I'm don't think it's the solenoid, as when I push the trigger the gas comes out of nozzle. It just feels like the pipe is a bit loose.

I don't want to dismantle this and then end up buggering it completely, but at the same time I can't have gas leaking out of it. Would it be easy to take this apart and have a look?

 

[PTvor]

If you regard 1 and 2 as the coarse settings, and Min and Max as fine settings within 1 and 2, it makes sense.

You've got a choice between it working unacceptably, or trying to fix it and risking finishing it off. I'd take the view I didn't have much to lose and dismantle the torch, carefully, with a view to finding the leak, using a bit of soap solution. It's probably a bit of perished tube or something which has slipped off. I haven't taken one to bits, but that's what I'd do. It sort of depends how much you like fiddling with and fixing things like that.

You might get a better response, and from someone who's actually fixed one of these torches, by starting a new thread with a title about a problem with a torch and not an electrical problem.

Min 35A @ 60%, Max 80A @ 15%. Not a very well specified machine. It looks as if there was a hole punched out for a fan on the deluxe model and you could improve the cooling by adding a box fan, if you can find one cheap. You might have to mount it externally.

 

[scotto75]

It sort of depends how much you like fiddling with and fixing things like that.

My life is filled with stuff that I either bought broken and needs fixing, or is broken and needs fixing because of my fiddling. One of the reasons why a welder would come in handy!

I'll give it a go. To be honest, I was given it to do some mods on motorcycle frame, and not sure if it'll be up to the task. I'm guessing from the settings that it'll do 1 - 1.5mm, maybe 2mm tops? I'll try it out on some 2mm scrap I have and see what it's like. If I can get the torch working properly, I could always put it up for sale and use the money towards a machine with a bit more power and flexibility.

 

[scotto75]

Oh yeah, thanks for the help!