Thread: CIG Eaywelder EC - dead

Originally Posted by nexusone

Hi folks, thought I was pretty clever picking this up at a clearing sale for $30 bucks. Plugged it in - fan went - thought I was homme, but alas no arc. Checked leads etc still no arc. all looks good inside and no components burnt out.

Any common tricks with these, or basic things to look for I have missed?

Steve (now feeling not so clever)

It doesn't sound good, Steve. These are a simple machine. I'm thinking that either the transformer is kaput or there is a loose connection somewhere. Ramp it up to full amps and see if you can get a buzz out of it (by sound, not feel!). If it remains dead, I'd unplug it and open it up and look for something obviously wrong, like the connections leading to the work and electrode cables. This is where you need a multimeter, to make sure there isn't a break in the connections. If there is nothing obviously wrong, you have to decide whether to take it to a welding repair shop. If I owned it, I wouldn't, simply because the repairs will cost more than these are worth (given that there are plenty around).

Hi,
These little units appeared around 1987 / 1988 and were the forerunners to the hi tech units we see today.

The EC part of it -the electronic control is. From memory I think they were still steeped control-thats is the amps had incremental fixed points.

There are some specialist repairers around with some excellent tradies. Electricians that specialise on welders are unfortunately few and far between.

I had a look in ebay and they had bid up to $200. I would not offer any more than $100 and would not spend any more on it than that.

Grahame

Thanks for the info. Yes these were the earliest of the electronic controlled models.

Being not easily defeated i have kept digging and investigating. I know all about the frequent warnings of not opening machines etc etc, but feel comfortable doing so.

So - cover off. Checked all leads and power cord for continuity. OK. Checked primary windings of transformer (copper) OK. Checked secondary windings (aluminium leaf) OK.

This welder has a transformer with 2 tappings (hi and low amp ranges). There is a single potentiometer which gives continuous adjustment within the amp range. The leads from the pot go to a tiny circuit board and that is about it.

The 240V in is fine, and fan works. Voltage between electrode and earth is only 5V. Voltage at inputs to primary winding around 15V. So transformer most likely ok, just not getting enough power in.


So fault most likely on circuit board. No visible damage (burn marks etc). looks just like a small amplifier circuit with one transistor. 3 capacitors, 5 resistors, one tiny IC, and a big transistor looking thingy on a heatsink.


Bit of research later I find this is a TRIAC (triode for alternating current) which is like a transistor for AC. Essentially a small signal current (from the pot) controls how much current flows to the main transformer inputs.

Tested all resitors OK, and pot OK. So most likely candidate failed is the TRIAC (obviously it gets hot or wouldn't need heatsink).

Have found a procedure to test a TRIAC, so will try that tomorrow. Will keep you posted.

Steve

Originally Posted by nexusone

Thanks for the info. Yes these were the earliest of the electronic controlled models.

Being not easily defeated i have kept digging and investigating. I know all about the frequent warnings of not opening machines etc etc, but feel comfortable doing so.

So - cover off. Checked all leads and power cord for continuity. OK. Checked primary windings of transformer (copper) OK. Checked secondary windings (aluminium leaf) OK.

This welder has a transformer with 2 tappings (hi and low amp ranges). There is a single potentiometer which gives continuous adjustment within the amp range. The leads from the pot go to a tiny circuit board and that is about it.

The 240V in is fine, and fan works. Voltage between electrode and earth is only 5V. Voltage at inputs to primary winding around 15V. So transformer most likely ok, just not getting enough power in.


So fault most likely on circuit board. No visible damage (burn marks etc). looks just like a small amplifier circuit with one transistor. 3 capacitors, 5 resistors, one tiny IC, and a big transistor looking thingy on a heatsink.


Bit of research later I find this is a TRIAC (triode for alternating current) which is like a transistor for AC. Essentially a small signal current (from the pot) controls how much current flows to the main transformer inputs.

Tested all resitors OK, and pot OK. So most likely candidate failed is the TRIAC (obviously it gets hot or wouldn't need heatsink).

Have found a procedure to test a TRIAC, so will try that tomorrow. Will keep you posted.

Steve

I feel like I've just given financial advice to Rupert Murdoch.

Originally Posted by nexusone

The 240V in is fine, and fan works. Voltage between electrode and earth is only 5V. Voltage at inputs to primary winding around 15V. So transformer most likely ok, just not getting enough power in.


So fault most likely on circuit board. No visible damage (burn marks etc). looks just like a small amplifier circuit with one transistor. 3 capacitors, 5 resistors, one tiny IC, and a big transistor looking thingy on a heatsink.




Steve

Sounds not dissimilar to a problem with my transmig 160 a few months ago.

I sent some digital pics of the circuit board to a techie friend and he diagnosed some potential dry solder joints on it.

10 minutes with a soldering iron and it hasn't missed a beat since

Rossluck - don't be fooled. I know next to nothing about this stuff, but find these days there is a vast array of tech and fault finding info avail on the web. So I like the challenge of nutting out a problem, and i get to learn a bit along the way.


As for fault finding, Just to be sure it was the circuit board, i bypassed it (ie connect power to the transformer without electronic choke). In theory welder should weld at max amps (130). WEll is welded beatifully.

So back to the circuit board - I phoned CIGWELD, and they sent me a circuit diagram. A+ for service from them. Last year they sent me a manual for my 350pulse mig, so they have been excellent.

Anyway, was able to confirm all resistor values from circuit diag. and also diode with a basic multimeter.

I pulled the triac out and tested it with a light globe and resistor as per web, and it triggered and latched ok. Doesn't guarantee its ok, but shouldn't look here first.

No dry solder on board (board is only 2" square - we are not talking complex).

So by process of elimination fault could be

a) capacitors (3)
b) triac
c) integrated circuit chip

So, have bought 3 capacitors for 3 and will replace them today, for a $3 investment.

If that does not work, replacement triac costs $22 so would have to think long and hard whether to spend that or just cut my losses.

Steve

If the IC is the problem I don't like your chances of getting a replacement for it. Sure as hell it won't be a standard IC.
Doubt the capacitors are the problem. Electrolytic's usually fail with dramatic results.
I'd just touch the soldering iron to all the solder joints just to be on the safe side. Often a joint can look good but is not.

After eliminating the capacitors and triac as possible failed components, by process of elimination it came down to the IC integrated circuit. Can't get a replacement so I have conceded defeat.

Could have by-passed the circuit and used it as a simple 2 setting welder (like the metalcraft version of same welder), but not much point, so after salvaging work leads etc she is now in the scrap bin.

Probably got $30 of fun and learning, plus some leads in good nick, so will notch that one up to experience.

Steve

just connect it up as a 130 amp welder

Originally Posted by nexusone

Probably got $30 of fun and learning, plus some leads in good nick, so will notch that one up to experience.

Steve

Well written, Steve. My sentiments exactly. I enjoy the process.

Yeah. Sounds like me. My motto is 'It ain't broken till I'm finished with it'.