PCB Problem

[EWL999]

Hi everyone, first time on here so I hope I am using the system correctly. I have been trying to convert my wire feed drive to the system described by bump but I am having problems. The welder was a present from someone I did a good turn for and its three to four years old. As a fitter for many years and numerous car repair projects I thought I could mig weld until I got this "welding" machine, which seems to be a common thread. Anyway the first conversion I did was to use a 12 Volt battery charger with a Maplins speed controller, 12 volt relay powered by the original motor wires and it worked great EXCEPT there was not a big enough feed for the thick stuff and the wire kept burning back to the tip on thick aluminium.
The welder did weld the same aluminium in its original form from the manufacturer but again like someone has commented before, you could never rely on it doing it.
In order to get a faster wire feed I thought I would convert to the system outlined by bump. I had a transformer that was rated at 28 volts 9A and when I put it through a bridge it was giving 25 volts, so I thought I would chance it, but perhaps not such a wise decision with hindsight.
Now in the process of doing the first mod I coupled a wire up incorrectly and burnt out R2 and a portion of the potentiometer. I replaced the pot, R1 and R2 and the machine functioned back as the makers speck again, but when I coupled up bumps mod the motor started to work immediately the machine was switched on and R1 started smoking.
Before I started trying to trace what was up with my version of bump's mod I thought I would get back to making the machine work to the manufacturers spec and here lies the problem. I have replaced R1, R2 and the pot and checked R5 but now the original wire feed speed controller starts fast, slows down towards the center of its rotation and speeds up as it gets to maximum rotation or fully clockwise and on top of that R2 starts smoking when the weld switches are put on maximum. I have tried adjusting the pot but it doesn't solve the problem. In fact the pot has to be on near maximum to get it to run on the minimum cycle.
I would appreciate any constructive help on the matter.

 

[Jake SS]

Would forget about the "mod" and put it back the way it was originally as per manufacturers specs.

The problem with the mod in question is so in depth and dangerous to people that do not know what they are doing should never be attempted in the first place.
Some people think they know but really don't have a clue.

Just because the machines are the same brand people think that if they do everything the same it will be OK. When in fact it is the opposite, pcb's, wiring, terminals, components etc vary between models of the same brands. Even the same model can and does have different PCB's and wiring.

These type's of "mods" should never be posted on an open forum!

I hope that the moderators delete these mods from the forum before someone is actually injured from attempting them!!

Yes I have stated this before but it fell on deaf ears.

If you do not like your machine sell it and get another one.

Cheers

 

[EWL999]

Thanks for your comments, but I think they are a bit defeatest. I know enough about electronics to keep it safe and frankly perfecting a machine and making it better than the manufacturers spec is half the fun.

 

[R Kraft]

It sounds as if you have the smoking resister, in parallel instead of series, or some other horrible thing.
You need to restore your connections to the original configuration.
This may help you see where you went wrong.
http://www.mig-welding.co.uk/forum/attachment.php?attachmentid=9251&stc=1&d=1243152742
Robert

 

[BChild]

These type's of "mods" should never be posted on an open forum!

I hope that the moderators delete these mods from the forum before someone is actually injured from attempting them!!

Yes I have stated this before but it fell on deaf ears.

Wonderfully helpfull post - would certainly empty out the SIP section of the forum nicely

The internet is like buying a car - buyer beware - approach with caution etc etc

Thanks for your comments, but I think they are a bit defeatest. I know enough about electronics to keep it safe and frankly perfecting a machine and making it better than the manufacturers spec is half the fun.

Totally agree but I'd wait for a few of the more experienced contribuitors to assist

 

[malcolm]

Wonderfully helpfull post - would certainly empty out the SIP section of the forum nicely

Jake made a very good point. There are a whole lot of differences between the various model years of SIP welders, and so far as I can see nobody has posted bullet proof instructions for modifying the things. With that being the case a fair bit of knowledge will also be required to do things safely and effectively.

With that said, there's some more info on bchild's thread: http://www.mig-welding.co.uk/forum/showthread.php?t=8028 but still not the full answer.

There are no deaf ears on here, but I can't think of a sensible way for people to share their findings and experiments with other people on a forum without the rest of the world getting a look. It is useful info in the right hands. In the wrong hands it might be like some fellow on the internet telling you to jump off a bridge. Can't see a sensible way for members to add disclaimers to their posts, though they would be worthwhile in modification threads.

 

[BillJ]

It is useful info in the right hands. In the wrong hands it might be like some fellow on the internet telling you to jump off a bridge.

Not quite. It's like some fellow on the Internet telling you how to get to the pub without knowing where you're starting from. His intentions were the best. He wanted you to get to the pub. You wanted to get to the pub. Neither of you expected that you would walk off that bridge...

This is the reason I've only posted schematics in the SIP/Cosmo forum rather than "Cut the blue wire..." procedures. I'm sorry if it isn't enough information for you to work with but it's the best I can do without knowing exactly where you're starting from. As Jake and Malcolm say, there are a load of differences even on the same model. You cannot guarantee that blue wire is the same on all models. On some it might be 24V. On others it might be 240V.

Where I'd disagree with Jake is about putting it back as the manufacturer intended it. Some of these welders turn out to be rubbish, yet they cost a fair bit to buy new. I wouldn't have put my SIP up for sale at any significant fraction of the price I paid because I'd have been ripping someone off. Therefore my only option to get my money's worth (having unwittingly bought a load of crap) was to modify it until it was half-decent. That's assuming I remained within my ability, which I did.

 

[EWL999]

Thanks for all your comments and particularly R Kraft for a sensible diagram. I have also been advised to change the transister and will let you know if that helps.
Coming back to the issue of welder mods I would be the first to accept that some of the mods on here look dangerous if left as demonstrated, but most people have a bit of common sense and would guard a transformer that was easily accessible when in use.
As far as the electronics go, providing you are strict with yourself about high and low voltage parts of the system, then trying to improve the system at worst will ****** the PCB if you get it wrong. The problem arises if someone inadvertantly tries to put 240 volts in the wrong places, but with a modicome of common sense that can be avoided and surely we live in a big enough nanny state already and if it carries on like it is you will shortly have to call a doctor in to clip your toe nails.

 

[Jake SS]

Thanks for your comments, but I think they are a bit defeatest. I know enough about electronics to keep it safe and frankly perfecting a machine and making it better than the manufacturers spec is half the fun.

No not being defeatist just realistic.
After reading your post it does not give me confidence in your ability to do the mod.
It is not a matter of joining up the dots.

To do a mod you have to know exactly what you have and how it works, not what someone else has and think "that's pretty much the same as mine"

With electrical you have to start with an exact circuit of your machine.
Then know exactly what you want to do to your circuit to make it work for your machine.
So you have to draw out another circuit of the mod applicable to your machine and go over and over it to make sure that it will work and not cause any shorts and above all that it will be safe to use.

You cannot add a bit here and a bit there and hope for the best.

There is only one way of doing a mod "the right way"

With a MIG you have 3 things that must work in conjunction with each other, electrical, electronic and mechanical.
Get one wrong and forget about it, no second chances.


BCHILD says
"The internet is like buying a car - buyer beware - approach with caution etc etc"
You must be joking, I do not see the relationship between buying a car and playing around with electricity.

I am all for improving something the right way though.

Malcolm
The only bullet proof way of doing these mods is as I said above, also the person has to be totally capable of carrying out the mod.
To repeat myself must start with a circuit of the machine in question.
Not have a look in the shed and pick out bits and pieces and " yeah that will fit in that space" etc.

Could go on but have to go out.

Cheers guys

 

[EWL999]

Jake I think your are getting a bit high and mighty about this lot. We are only talking about finding an alternative method of suppling a low voltage DC motor, and not rewiring the space shuttle. I am not trying to blow my own trumpet here but I am a time served Rolls Royce apprentice and have dabbled enough in electronics to keep everything safe. I might not know the fine detail but frankly I am enjoying learning and experimenting and quite simply if I can't make it work I will buy a new PCB, but so far in life I have never been beaten by an engineering problem and don't subscribe to the theory of "leave it to the expert" because more often than not they either can't do it or want to rip you off in the process. I totally agree with you that the process and outcome of the mod should be safe, but give me the right to experiment on my own machine for god sake.

 

[Specialist]

Well, was thinking about this and well, did not expect to post anything really, but I digress - to pull everything (schematics, instructions, how-to) about anything that might be dangerous from internet for example, would be equivalent to those obnoxious stickers reminding us that "coffee is hot", or a sticker I saw on a hairdryer said "do not use underwater". Some things are dangerous indeed, but if we deliberately behave like no one knows nothing about anything, and remove every information from all around us, then we will, indeed, make ourselves uncapable of doing almost anything.

I design stuff for a living - pretty responsible, complex stuff in engineering. Expensive, too. If I am the "manufacturer" of my construction, machine or anything else, who do I turn to send it back to when it doesn't work ok? Off course I have to analyze it, find the cause of the problem, then rectify it. So what is the problem if for instance, I find a faulty welder (which is a really simple piece of machinery compared with something I have to construct work-wise, and yes, the saying "it ain't rocket science" does not apply here) and I can repair and redesign it 10 times better the the factory could? Obviously, since I am modifying it, responsibility is mine as to the result.
The same applies to anyone following, for example, instructions from a post and modifying their welder on their own. Everyone is responsible for their own actions, and while those actions need to be sensible and not too complex for the knowledge level of the person doing it, I cant see why should there be a need to forbid everyone form even thinking about it.

Off course, safety is paramount, and I do not approve somebody doing those modifications who does not have the needed level of knowledge or experience. Also I do not recommend doing it for anybody who is unsure about what they are doing it, and lastly, everyone who does it should understand that the are doing it on their own sole responsibility - if they do something dangerous and end up being hurt, only they are responsible.

 

[BChild]

BCHILD says
"The internet is like buying a car - buyer beware - approach with caution etc etc"
You must be joking, I do not see the relationship between buying a car and playing around with electricity.

Then you need to develop a sense of humor

What I mean is you need to be carefull - there is a lot of stuff on t'internet that is untrue or wafty - approach information contained on t'internet with the same caution you would buying a car - believe half of what you see and hear.

 

[Jake SS]

Well, was thinking about this and well, did not expect to post anything really, but I digress - to pull everything (schematics, instructions, how-to) about anything that might be dangerous from internet for example, would be equivalent to those obnoxious stickers reminding us that "coffee is hot", or a sticker I saw on a hairdryer said "do not use underwater". Some things are dangerous indeed, but if we deliberately behave like no one knows nothing about anything, and remove every information from all around us, then we will, indeed, make ourselves uncapable of doing almost anything.

I design stuff for a living - pretty responsible, complex stuff in engineering. Expensive, too. If I am the "manufacturer" of my construction, machine or anything else, who do I turn to send it back to when it doesn't work ok? Off course I have to analyze it, find the cause of the problem, then rectify it. So what is the problem if for instance, I find a faulty welder (which is a really simple piece of machinery compared with something I have to construct work-wise, and yes, the saying "it ain't rocket science" does not apply here) and I can repair and redesign it 10 times better the the factory could? Obviously, since I am modifying it, responsibility is mine as to the result.
The same applies to anyone following, for example, instructions from a post and modifying their welder on their own. Everyone is responsible for their own actions, and while those actions need to be sensible and not too complex for the knowledge level of the person doing it, I cant see why should there be a need to forbid everyone form even thinking about it.

Off course, safety is paramount, and I do not approve somebody doing those modifications who does not have the needed level of knowledge or experience. Also I do not recommend doing it for anybody who is unsure about what they are doing it, and lastly, everyone who does it should understand that the are doing it on their own sole responsibility - if they do something dangerous and end up being hurt, only they are responsible.

I have no problem with anyone trying to repair there own machine. It also helps the person gain more knowledge of the workings of his machine.
I have offered help to people to do so (to a limit).
So long as the person is capable of doing so then that's fine.
I do not have a problem with the actual mod, just the way it was done and it is not applicable to every model

I find a faulty welder (which is a really simple piece of machinery compared with something I have to construct work-wise, and yes, the saying "it ain't rocket science" does not apply here) and I can repair and redesign it 10 times better the the factory could?

Really?

Cheers

 

[fingers99]

For all that, I'd be inclined to return to the original settings. Everything -- and that may not be a lot! -- I know tells me that MIG welding aluminium reliably is pretty much impossible on home equipment. It'll work (usually badly) sometimes, not work at all at other times.