Warning: Burnt Transformers

[mechanic416]

Just wanted to let everyone know that they should unplug or shutoff the circuit breaker to their plasma cutters and welders when not in use.

I have had a lot of plasma cutters and a few welders with burnt step-down transformers come in the shop over the last few months.

On a lot of these machines this transformer is on the power PC Board. This PC board can cost upward of $1000 yes thats 1000 with 3 zero's.

The power switch does not cut off the power to the hole machine. The power transformer and PC Board is hot all the time.

So just keep this in mind and shut the breaker off or unplug them and they will last longer.

George

[farmall]

What MAKES and MODELS?

It's too bad companies leave sections of the machine hot. A "power" switch should be a true disconnect.

[G-son]

If it's only the transformer that breaks it should be a cheap fix, transformers are relatively cheap and even if it doesn't fit the holes in the board it can be connected with wires and mounted whereever there is room.

I actually was asked to try to find out what's wrong with a friends (cheap) MIG welder. I guess you won't be suprised that I found a small 230-24V 1.5VA transformer on the curcuit board with a burned primary winding. I think I have a bigger 230-24V transformer somewhere, easy to connect and see if that fixes it, if it does it's a cheap fix. If it doesn't, well, he should be buying a better welder anyway, or concentrate on getting his ~40 year old MIG welders back to life instead - if they work, they'll work alot better!

[mechanic416]

Most of the ones I am seeing are the Lincoln migs and the Thermal Dynamics cutmasters.

Check your manual for the wiring schematics if the power wires go to a contactor before the switch then it is hot all the time.

[mechanic416]

Yes some times transformers can be a easy and cheap fix. But then like the Thermal Dynamics Cutmasters were the transformer is made for them ONLY and can't be bought by itself you have to buy the PCB and that is $1008 dollars.

You also have to know what the high and low limit of the PCB is because some transformers say 230VAC/24VAC and really put out over 30VAC and the PCB can't take that much voltage what happens next(FRY)

I am just saying take the time to unplug it or shutoff the breaker. It will save you time and money in the long run.

[glock36]

Message well heeded , thank-you for the heads up

Sent from my Desire HD using Tapatalk 2

[galencwi]

Originally Posted by mechanic416

Most of the ones I am seeing are the Lincoln migs and the Thermal Dynamics cutmasters.

Check your manual for the wiring schematics if the power wires go to a contactor before the switch then it is hot all the time.

Thanks for the info George Do you see a lot of Millers with this problem or do they have the pc boards isolated in most models?

[shortarc]

I always unplug any of my welding equipment when not in use. I have had first hand experience with what a bolt of lightning can do and we have plenty of it.

[LarryO]

Thanks for the heads up.

On a couple of occasions, i have left my machines on for a day or two. Only happened once or twice.

I always try to turn off at the wall.

[76GMC1500]

I'm gearing up to buy 4 PC control cards for Lincoln Idealarc CV-300 welders. I've got 5 dead units and only one left operational. Besides the incredible amount of welding and grinding debris deposited all over the inside of these welders (we don't really take care of them considering we only paid $100 a piece for 8 of them) they get left outside. But the cards are dipped in resin. There is no corrosion or carbon tracks on them. I'm guessing the failures are due to our welders practice of "trigger welding" uphill passes. Off and on. That's just like pulling the battery cable of on your alternator which can kill a the voltage regulator in your alternator. Electronics don't simply wear out. I've seen equipment run for 30+ years straight. Leaving it on keeps it warm which keeps condensation (corrosion) from happening. Many of the controllers I work on actually have strip heaters that are energized from additional sources so that they stay energized while the equipment is de-energized.

As an FYI, Lincoln manuals specifically state that most all welder related problems originate in the PC control cards. They pretty much say replace the card first, then trouble shoot from there. I'm going to be out $370 a card for our CV-300's. That's close to 4 times what we paid for the welder but I know the rest of the welder is good.

[BrianC]

That's a great tip. I always flip my breaker when I'm done for the day, not for that reason, but for a safety reason, as there is sometimes something laying across or near the 220 line,never thought of this one.Thanks,
Brian

[Mondo]

Oh kwap! Do we need more gov't regulation to require manufacturers of electrical devices to design and build their products such that the "ON-OFF" switch is a true disconnect??

I turn off every electrical device in my house, snap off the breaker powering the hot water heater, unplug the refrigerator, unplug the alarm clock, then go outside and watch the meter wheel turn. Stereo system, TV, TV Cable box, computers that are "shut down" are all drawing small currents. If this nation and society is so energy concious then why the heck are all these devices still demanding electron flow from the grid when "turned off" ?????????


Good tip, though! I will check my Lincoln welder and Hypertherm plasma cutter.

-Mondo

[stevewm]

Originally Posted by mechanic416

Most of the ones I am seeing are the Lincoln migs and the Thermal Dynamics cutmasters.

Check your manual for the wiring schematics if the power wires go to a contactor before the switch then it is hot all the time.

That may explain the relatively new looking Cutmaster 39 I picked up at a local pawn shop. I had been watching the price drop from $999 to finally $599 when I pulled the trigger. Couldn't test it there but they have been good about guaranteed working.

I fired it up at home and could only get a weak arc on 110v and nothing on 220v. Pulled the case off and saw nothing but the diagnostics lights showed a power supply issue on the DC side. Called Thermal Dynamics and after running through some more tests with them they concluded the power supply, one huge PC board was bad. Cost new? $600, same as I had paid for themachine. Fortunatel, I was able to return it for a full refund.

[farmer37]

Unplugging is the only way to avoid damage from lightning strikes on the power line.Lightning will jump open breakers and switches.