Help! PP256 A/C dropping out after 1-2 seconds of arc start

hey guys

I have owned my pp256 for 2 years now and have had small issues but this is a big issue as I'm in the middle of a job and trying to meet a deadline and the aluminum welding I need to get done is now halted....

welds fine in dc, in ac mode, it hf starts, creates an arc and then drops out back to the weak hf arc. I've tried the pedal and the torch switch same result.

I had to adjust the points when I first received the machine but cannot remember where they are too try that. but this is a different symptom than when I was directed to adjust the points.

Has anyone had an issue like this and how did you correct it? I need to get work done today and am about to go buy another welder if I can't get this fixed and would really prefer not to have to spend the money if it's something simple.

thanks!

Chris

That's part of the reason I caution people that these multi tig/stick/plasma units are not for production work.

With that said, have you tried to PM ray or contact tech support? tech@everlastwelders.com

It could be a simple issue like a loose wire. I'd check to make sure all wires are in place first.

I have not contacted tech support yet, I assumed they were closed on Sunday. I am happy to pull the covers and check for loose wires I just don't know which ones to be checking. I was hoping someone else has had this issue and might direct me too what I should be looking at.

I don't have rays email but would be glad to send him one.

thanks guys!

Chris

The above email is ray's email. He's been known to answer questions on sunday afternoon.

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Originally Posted by performance

The above email is ray's email. He's been known to answer questions on sunday afternoon.

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Awesome, Thanks a bunch I will send him an email now!!

Chris

Quote:

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Originally Posted by performance

That's part of the reason I caution people that these multi tig/stick/plasma units are not for production work.

With that said, have you tried to PM ray or contact tech support? tech@everlastwelders.com

It could be a simple issue like a loose wire. I'd check to make sure all wires are in place first.

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Mark,

I had not been cautioned of that, I rarely use the plasma function and actually have since purchased a separate plasma unit, are the dedicated AC/DC Tig machines more robust and dependable in a production environment? if so do you take trade ins?

Chris

PP256 Duty cycle of 35% @ 250A
PT250EX Duty cycle of 60% @ 250A

That spec says a lot about the kind of usage they were designed for.

I wonder why that is though, are the actual parts more robust in the EX? OR is it a matter of better cooling (because of space restraints) in the more "packed" 256?

I've been doing a lot of 1/4" 6061, Full Power, welds in my 256 lately. I have been Extremely conscious of the duty cycle and will do all sorts of things to spend more time between welds.

I use just one clamp (even though I have Many) so I take the time to move it, and wirebrush each joint as I go, anything to cause some delay ;)

I've been wondering, if I make a 12sec weld and wait say 15secs, but only do this 6 times in a row. Am I exceeding the 35%? I mean I know it's not off 65% of the time but to do another 6 welds means repositioning stuff that takes a full min or two before I start again. How long of an "ON" time is it based on? There has to be some residual, certainly you can weld 20secs and put more heat into the machine than 20 2-second welds with even a second between...

I would imagine it's a little of both. There are extra parts stuffed into basically the same size case, so cooling is a challenge. But also it is the basic design. They try to meet all the design goals for each market. Size, duty cycle, price, etc.

Duty cycle is typically measured over a 10 minute period. So for every 3.5 minutes of welding you need 6.5 minutes of cooling off. Also this means the fan needs to be running, so don't just turn off the welder between beads. Heat is the enemy of electronics, so take it easy and your machine will last a lot longer.

But you certainly couldn't make a 10min continuous weld with one of these - could you?

Even if I only do a moderate amount of welding at 120A, I let the machine run for at least 10mins after I'm done...

Also, since a lot of use are using Water Cooled torches, wouldn't it have been great to have the option of connecting the cooler to the welder itself for Transistor cooling!

Only if you were running it low enough that the duty cycle was 100%. The measured time is 10 minutes, so that is what you use to calculate the duty cycle. As the output goes down the duty cycle goes up. You can find this in the spec sheet. Just like you can't stretch this time period. So welding 5 minutes and cooling 20 minutes still exceeds the duty cycle of a 35% machine. In any 10 minute period, the total weld time can not exceed 3.5 minutes.
Water cooling inside the case would require drop dead reliability and fail safe systems. Mixing high voltage and water is often a recipe for disaster.

There are two inverters inside a 256, one for Tig and stick, and a separate one for plasma. And oneboard to rule them all, and several shared analog circuits (such as the high frequency on the older units) which are hard to optimize for one or the other (speaking as a layman to electronics). Things are more tightly spaced, and there are a lot more parts inside period. Where you have more parts, you have more potential for failure. Not saying anything is going to HAVE to fail, but rather the potential exists.

As Rambozo explained, duty cycle on our units is measured in percentage of time out of 10 minutes. It's also measured on our units at maximum output, though some companies like to fudge really badly and give a lower amperage value to improve their duty cycle statistics. You'll hardly ever find a MIG's duty cycle rated at full amperage, though most of ours are.

The lower the output, as he said, the greater the duty cycle. I've tried to explain duty cycle in different places, and always ends up with an argument about what 100% duty cycle means.

It doesn't mean that at 100% duty cycle level the unit will weld indefinitely. It means that it will weld 100% of the 10 minute length of time without needing a break...That doesn't mean it won't need one at the 11th minute, though it practically could be depending upon actual amp setting etc. It's just a theoretical threshold, and it could actually be less or more.

I was perusing a competitors manual the other day for comparative information, and one of the sections discussed what to do IF the duty cycle limit was hit. It said, to allow the unit to cool for 15-20 minutes...well you do the math. I recommend 10 minutes of cooling if duty cycle threshold has been reached, but well maybe we should up our figures too.

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Originally Posted by Rambozo

In any 10 minute period, the total weld time can not exceed 3.5 minutes.

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But again, you really couldn't do that continuously. You couldn't run All-Out for a 3-1/2min bead without overheating. So there's some factor that says, from a "cold" start, it can be run for so long before the cooling can't keep up. In practical terms, I wonder where that is, as referenced to my repetitive "12sec" welds...

As for water cooling, I just remember the overclockers having some sort of CPU "cool pipe" heatsink, that was watercooled outside of the case itself. Too bad it can't be applied here as so many of us have coolers right next to our welders because heat IS the enemy!

Quote:

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Originally Posted by performance

There are two inverters inside a 256, one for Tig and stick, and a separate one for plasma. And oneboard to rule them all, and several shared analog circuits (such as the high frequency on the older units) which are hard to optimize for one or the other (speaking as a layman to electronics). Things are more tightly spaced, and there are a lot more parts inside period. Where you have more parts, you have more potential for failure. Not saying anything is going to HAVE to fail, but rather the potential exists.

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So the components (the Transistors themselves) are the same? It's the cooling limitations that's the difference?

And the more complex theory is just what I thought in the 70's when working as a mechanic and cars were just getting computerized. We all thought ""Who's gonna be able to fix all this"? Remarkably, cars got 10X more complicated and 10X more reliable at the same time because of it! ;)

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Originally Posted by Blaster

But again, you really couldn't do that continuously. You couldn't run All-Out for a 3-1/2min bead without overheating. So there's some factor that says, from a "cold" start, it can be run for so long before the cooling can't keep up. In practical terms, I wonder where that is, as referenced to my repetitive "12sec" welds...

As for water cooling, I just remember the overclockers having some sort of CPU "cool pipe" heatsink, that was watercooled outside of the case itself. Too bad it can't be applied here as so many of us have coolers right next to our welders because heat IS the enemy!

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Actually, yes, you should be able to lay down a 3.5 minute bead without overheating the machine. While I never recommend maxing out anything if you want a long life, the machine should be capable of doing that. That is what duty cycle is all about, how long before it gets too hot. In this case 3.5 minutes before the semiconductor junctions get too hot. Then it will take 6.5 minutes for that heat to conduct into the heaksink and be radiated away.

Yes a heat pipe system can help to change the duty cycle curve. It basically emulates a larger heatsink in a smaller space.

If it does not exist already, I'm sure someone, someday will construct an integrated welder/cooler that uses the liquid cooling to cool the power supply as well as the torch. It will probably be a very small package with a very large price tag, that fills some industry niche.

They actually were HORRIBLE during the 70's. American quality and reliability took a huge nosedive. Complicated they were with emissions systems etc. It wasn't complication, it was claptrapification. Things like electronic ignition fuel injection etc, actually simplified things. There were less total parts in many circumstances...these parts usually gave little problems. Once more simple emissions were worked out things once again became more simplified under the hood, and engine compartments became recognizable. I think the idea to call something more complicated is in the eyes of the beholder. For an electronics person, and diesel injection pump may seem complicated...but I've rebuilt them on the tailgate of a pickup (and no a clean room isn't 100% necessary to do a proper job...it helps, but if you stay clean and keep it clean, all will be ok.

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Originally Posted by Rambozo

Actually, yes, you should be able to lay down a 3.5 minute bead without overheating the machine..

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WOW! I'm Very Surprised to hear that...

I would have thought that maxing the pedal and counting, one thousand one,,, one thousand two,,,one thousand three,,, wouldn't take anywhere's Near 200 times for things to melt down!

Don't worry , it's not gonna be ME who tries it :D hehehe...

still trying to get this resolved. Ray stated that the red light on the front of the machine is an overtemp light and that it may not be cooling but i can get it to happen from a dead cold machine inside 3 seconds of welding at 100amps and plenty of airflow through the machine from the cooling fan. he also thinks it could be a faulty temp sensor. but im not sure where itis located to jumper it for testing. any help? schematyics etc to help me find it?

thanks guys!

Chris

Attachment 11357Attachment 11358Attachment 11359

Above are pictures of the inside of the machine, I removed the protective plastic sheathing from both sides for better viewing. does anyone see anything that jumps out thatmay be wrong or can anyone point me to the temp sensor so i can test it?

Thanks!

Chris