Thread: New Broken Welder

OK, I just want to start this thread by saying I have used some serious POS stick welders with limited duty cycles and it really kills me to have to wait for a welder to cool off before finishing a job... So, for a while I've been keeping an eye out for a second hand welder that has a decent duty cycle on it, and I've been open to purchasing a broken unit to repair. Well, along came a man with a faulty Cigweld 250i unit, with the mig and stick hand pieces and an earth lead. I considered what buying a faulty welder could lead to, but I decided to jump on it either way. $200. Now I have the task of getting this unit repaired. The faults that show are error codes on the display. Error 2 shows up initially, however the unit can still be used. Once I strike an arc, it seems there is no control over the current, it literally gouges holes into the work piece at any level amps, then "Error 8" is displayed. I have had an electrician (from work) take an internal look at it, and he says the main power board needs to be replaced. Question is, where can I get one? I realize repairing a welder has serious safety implications and I am guessing that only certified repair businesses will take on such a task, so I am not interested in attempting the repair myself, I am just interested in how I go about getting it done, and where would be the best place to start (to get quotes etc.) My location is Townsville Qld so any local businesses that anyone has had experience with would be very beneficial. Any general experience with this sort of thing is also welcome, and also if you actaully think I should just pass it on and get rid of it I realize that could be what really needs to happen, however, I am of the firm belief that this can be repaired, just at what cost?

Cheers,

MOA

You may be able to source a board through your local CIGWELD agent or else you willneed to find a repairer in your area that is affiliated with CIGWELD.
Why did the previous owner not repair it? For a $1000-$2000 unit it seems strange that a unit viable to repair is sold off for $200. Perhaps a little more digging and delving may be a good idea before committing too many dollars to this one.

Hi, PM sent.
Kryn

You'd need a lot of faith in your electrician before you order a Main power board just to see if its that. I'm sure the board could be repaired relatively easily, but it seems everyone just replaces circuit boards nowadays.

I couldn't see a service manual for a 250i but the operation manual has a system diagram. It might be worth asking your electrician if he checked there is not a physical problem with the current sensor shown in appendix 2A (ie broken wire or plug disconnected) That would be too easy though, I'm never that lucky myself. Current sensor would just be a couple of coils of wire round the main output wire.

I think yours is a digital welder? I prefer a welder with lots of knobs because you can trace wires to the relevant area of the control board and have a chance at fixing them

I'd bet there is a lot of similarity to the welder in service manual.

http://victortechnologies.com/IM_Upl...6)_Jan2014.pdf

There's a lot of info in there that would help an electronics guy find a fault fairly easily, even if its not exactly the same.


Wish I could buy a welder like that for $200, but I'd be betting on the fact I could repair the main power board because I wouldn't like to guess what a new one is.

Actually i just found a service manual for a cigweld transmig 250i here
http://data.manualslib.com/pdf4/96/9...0f&take=binary
If that link doesn't work, let me know an email address and I can send it.
Error 2 and 8 relate to input voltage section. One says input voltage is out of range and the other is an input sensor fault. You could have quite a few things wrong and that's why no-one wants to spend time on it.

Gosh, that's a infinitely better manual than I got with my UniMIG

And it seems like a pretty damn good welder to boot.

That said, if you don't have skills to fix it yourself, I'm not sure of the economics of paying for someone else to do so.

Gee guys thanks a lot for the information! That is far more feedback (and good too) than I expected to get! There are a couple of electronics technicians at work that could likely take a look at it, but it will take some enticing (read beer).
I don't know why the guy sold it so cheap... He was asking $300 so I offered extra low and he just accepted. When I picked it up, the place looked like a backyard business, and the employees didn't seem very happy. Said they'd had time off recently coz work isn't going so well. Seems to be the way things are going in town here, lots of businesses closing up shop, and lots of industry workers looking for work. Sad to see.
I do have some novice->(intermediate?) skills with electronics. I have repaired underwater camera's and comm's for divers, fault find lathe and mill control boards, I built my own PID for smelting lead, repair outbaords etc. lots of things like that... But I was under the impression that most people wouldn't consider a DIY repair job on a 240v machine. I think I'll still ask the tech's at work to do it just to be safe. Looking at it myself would be a last ditch effort I think! I just don't have the elec background to refer to. I'm a mechanical tradesman.
Anyway, here's a pic of the welder. I guess it always helps to see what it's all about.
013.jpg
Thanks again for the help. I will see what can be done

Cheers.

No-one likes working on high current power supplies. There's always a risk of something exploding in your face.

The faulty codes you see are strange though and could just mean a loose connector plug inside. It might be the same plug that the current sensor goes through.

I never really found out for sure, but it might be technically illegal in Australia to work on 240V if you are not qualified, but if its not switched on, you are not working on 240V.

When you open up a welder you are quite likely to come across 340V DC which can remain for quite a while after unplugging. There is a bleed resistor to remove this voltage over a few minutes, but they are known to go open circuit. Of all the things to learn on, I'd say a 250 amp power supply would be the last thing to try. When I worked in a test room, the power supplies all got left for someone else, no-one rushed in to fix them.

Originally Posted by sossity

Error 2 and 8 relate to input voltage section. One says input voltage is out of range and the other is an input sensor fault.

Originally Posted by sossity

I never really found out for sure, but it might be technically illegal in Australia to work on 240V if you are not qualified, but if its not switched on, you are not working on 240V.

The explanation I was given (many years ago) was that it is illegal to work on hardwired devices but if it plugs in that is legal. (which is why plugs and sockets are available at hardware stores rather than being restricted to licenced people)

Back to the issue - if the error codes are for voltage out of range when it plugs into a standard supply then I would suggest the second is more likely - there is a fault with the sensor (which sometimes says the voltage is not right). As suggested it may be as simple as the sensor plug coming adrift from its socket.

Michael

Originally Posted by sossity

No-one likes working on high current power supplies. There's always a risk of something exploding in your face.

The faulty codes you see are strange though and could just mean a loose connector plug inside. It might be the same plug that the current sensor goes through.

I never really found out for sure, but it might be technically illegal in Australia to work on 240V if you are not qualified, but if its not switched on, you are not working on 240V.

When you open up a welder you are quite likely to come across 340V DC which can remain for quite a while after unplugging. There is a bleed resistor to remove this voltage over a few minutes, but they are known to go open circuit. Of all the things to learn on, I'd say a 250 amp power supply would be the last thing to try. When I worked in a test room, the power supplies all got left for someone else, no-one rushed in to fix them.

Honestly curious here, having repaired the odd welder in the past, although never an inverter type. Where does the 340VDC come from? Given the supplied voltage is 240V, there must be a step up transformer in the system. Why?

240V AC has an 'average' RMS potential of 240V. The peaks of the sinusoidal waves are V_peak= V_RMS *√2 = 340 volts.
So when you rectify 240V AC, the 'bumpy' DC voltage is 340VDC.

There is no step-up transformer. 340V DC is the result of the 240V AC sine wave being rectified and stored in a capacitor(s), where it reaches a DC value equal to the peak value of the sine wave (340V), not the RMS average value 240V. This 340V DC is switched electronically at high frequency into the primary of the welding transformer whose isolated secondary winding provides the welding current. The primary 340V DC is regulated to control the welder's output.

Chas.

Thanks to both Jhovel and Chas.
Now that you both mentioned it, I was aware of the peak versus RMS rule, but it got lost in amongst all the useless information floating about my scone at present