Everlast Super200P died. Performed "diode-ectomy". Now it's welding again!

My Super200P's welding function bit the dust while pushing it welding some very thick aluminum in the middle of last week. I burned one diode out of the high current diode array (24 diodes in this array, affixed to the massive air cooled heat sink.)

The symptom was, the welding arc just quit. The cooling fans and the gas solenoid kept working as they should. The "fault indicator LED" light also turned on (has a symbol next to it that looks like a lightning bolt.) Mike (everlast support) helped me troubleshoot it. When the machine was switched on in TIG mode, the fault indicator LED would turn on once an arc start was attempted. In stick welding mode, the fault indicator would glow immediately. There was no high frequency arc starting, and scratch starting was ineffective as well.

I troubleshot it as a shorted diode, in the 24-diode array. This is located on the left side of the machine (to your left while looking at the front) at the bottom of the heat sink. These diodes actually look like transistors (three pronged little black silicon things, clamped to the heat sink.) But looking up their part numbers, they are actually "dual diode packages."
(here is the datasheet on them: http://media.digikey.com/pdf/Data%20...FAF30U60DN.pdf )
Attachment 2394

Mike (everlast support) was super helpful diagnosing this, but perhaps a previous job experience I had in electronics industry a long time ago (I worked for an electric guitar amplifier manufacturer) didn't hurt either. I found the shorted diode by testing the continuity between the pins of all the "transistor lookling things" with my multimeter. The failed diode basically had a short (zero resistance) between two pins. Because of the way they were wired, a whole bank of the diodes all measured the short when they were installed, but after I removed the circuit board and did some further troubleshooting, I was able to narrow the short down to just a single diode.

My fix, at least at this point, was to simply remove the failed diode, (and other "shared diode packages" like it in the other diode circuits, which I thought were mostly likely to fail.) There were 8 circuits in the diode array, each driving 3 diodes in parallel. My temporary fix is to have each circuit drive 2 diodes, both in the same pacakge (to hopefully minimize the change of "thermal runaway", more info on that in a bit.) The 3rd diode in each circuit was from a shared dual diode package (which are the ones I removed.) You can read about the problems of putting multiple diodes in parallel here - (but basically - it's generally not a good idea):
http://wiki.answers.com/Q/Can_you_pu...he_double_load

Here is what my circuit board looked like after removing the "shared" dual diode packages, when it was still removed from the machine:
Attachment 2395

It remains to be seen whether this solution will actually increase reliability of the machine or not, but I can say that it fixed the machine, and it's back up and running. A better fix would be to replace the multiple parallel diodes with single diodes, with an equal or greater combined amp rating than the sum of the diodes it replaced. I am considering going this route at some point, but for now it's great to have my machine back up and running!
Attachment 2393
(Can you spot where the diodes were that I removed?)

The cool thing is, I managed to diagnose and fix this primarily by myself (and well, with some help from Mike over the phone, but I was the only one who touched my machine, and didn't need to send it out anywhere.) It didn't even take all that long - I had the problem figured out in less than a day, and after some research about the problem and fix, I was able to implement a repair solution (even if perhaps only temporary) in less than another day.

Mike and I are still working out the details of possibly another fix that will improve the reliability of the machine, by changing the diodes out for better, (non-parallel) ones. But in the meantime, I am up an running again.

So, if your machine breaks, and you have a little bit of electronics knowledge, you may be able to fix it yourself! You might not need to be as dependent on the warranty repair department as you thought, after all. ;)

If there is interest, I can post some tips on "how to" perform some limited diagnosis with a multimeter, how to desolder components from circuit boards, how to make a good thermal connection to a heat sink, how to remove this board from a Super200P. Other good things to do while you are deep inside your machine. (Just let me know.)

Anyway, it's good to have my machine up and running again! I hope this info is useful to you all.

I tell you what man. Those older mosfet units sure were put together nicely. If you sit one of those machines next to my 256 with the covers off, they just look nicer inside. Wires are run and routed nicer, more tastefully and so forth. I wonder if everlast still has any of those older mosfet units in stock. I wouldnt mind having one. Nice work jake.

good job on the fix. I just had to replace a 4053 chip for my pedal problems and it was a PITA to remove it. If I have to do it again I'll just build a specialty tip that heats up all the pins at once to to remove it

Another tip of the hat to Jakeru! A job well done, and well documented for the rest of us to use as a resource.

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Originally Posted by jakeru

My temporary fix is to have each circuit drive 2 diodes, both in the same pacakge (to hopefully minimize the change of "thermal runaway", more info on that in a bit.)

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Did this entail a trip to the Radio Shack for parts, or did you reuse the original parts?

I hope you replaced the heat sink compound also for the thermal connection to the heat sink.
You said you pushed it was the duty cycle running out or thermal environment?

Jakeru,
Considering that unit is as old as it is, and the issues that were faced with it, I'd say that the unit has held up well. I'm glad you had the skill to fix it quickly, and I dare say cheaply.

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Originally Posted by Wrenchtamer

I tell you what man. Those older mosfet units sure were put together nicely.

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Each time I delve more deeply into this machine, I get a better appreciation of its build quality, design, and value. Sure I find some minor flaws sometimes, (really, what machine this complicated that wasn't 100% robot-assembled wouldn't have a few things that couldn't be improved?) But often, I can correct any problems. So I'll take your statement as a personal compliment as well. :D

Example: on this board I worked on recently, I found three out of four of the brass circuit board standoff/mounts were damaged. The function of these standoffs are to support the weight of the board (taking the physical load off the diodes). I replaced them with beefy, M3 size stainless steel machine screws and broad, nonconductive nylon spacers.
Attachment 2402

Also, I've generally cleaned (scraped off any nonconductive rosin) and tightened any threaded connection that needs to conduct current, that I've had access to. Made sure connectors are properly seated, etc. I think a little "TLC" goes a long ways (and I don't think it's that hard to do, either.)

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Originally Posted by kenwhite

Good job! I'm sure it would have been a lot easier if we had schematics.

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Isn't that the truth. You know I'd be interested in even a very rough "lay of the land" schematic of the machine, that would perhaps go down to a major component / circuit board level of detail. IE: this circuit board's function is to "xxx" this connector between board A and board B has the purpose of "xxx". Adjusting this trimpot will result in "xxx" (Fill in the blanks?)

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Originally Posted by Timberwolf

good job on the fix. I just had to replace a 4053 chip for my pedal problems and it was a PITA to remove it. If I have to do it again I'll just build a specialty tip that heats up all the pins at once to to remove it

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I might have a couple tricks for you. The first is, a teflon-tipped desoldering / "solder sucker" squeeze bulb. You get a blob of solder nice and molten/hot, then you quickly can "suck" up the bulk of molten solder with it, especially if you stick a pin protruding through a circuit board into the tip and then release the bulb, it does a nice job.
You can see the solder sucking squeeze bulb in the lower right corner of this pic (which by the way, you guys may be interested in as well, for those cases where you just need to give that soldering iron a "quick heat boost" ;) )
Attachment 2397

My other tip for removing solder & soldered components is, get some "solder wick". It is a flat, fine-braided copper "rope" product that you press with your hot soldering iron against the solder you want to suck up. Once it gets hot enough, it will liquify and (via capillary action) draw the molten solder up into the solder wick.
Attachment 2399 Attachment 2398

But still even with those tricks, I agree removing a multi-pinned component without causing any collateral damage is "easier said than done!"

Just remember... soldering, just like welding, is controlling/manipulating the flow of molten metal. If you get "good" at one process, you'll probably find the other process not too hard to pick up (with at least a minimal investment in some basic tools, plus a little bit of practice.)

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Originally Posted by DaveO

Did this entail a trip to the Radio Shack for parts, or did you reuse the original parts?

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At this point, I reused some of the original dual-diode packages. The only parts I "added" were small aluminum spacer blocks I made to allow clamping of the diode packages to the heat sink, where the neighboring diode packages were removed. Here you can see the aluminum spacers I fabricated, cemented to the heat sink clamping bars:
Attachment 2400

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Originally Posted by acourtjester

I hope you replaced the heat sink compound also for the thermal connection to the heat sink.

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I had this thermal grease left over from a recent custom LED lighting project. Although perhaps overkill, I also did clean off all the old thermal grease before reapplying fresh. (If anyone wants to know where to purchase any of this stuff, let me know. None of this stuff need cost "an arm or leg") There is also something to be said for good clamping bar force, to really press that component against the heat sink. I found the heat sinks had a really nice, milled finish on them by the factory, so no need to mess around with those.
Attachment 2401

Quote:

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Originally Posted by acourtjester

You said you pushed it was the duty cycle running out or thermal environment?

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I was welding some thick aluminum, so I was pushing it with respect to the machine's welding output current, not pushing it with respect to ambient temperature environment. (It was just a normal, maybe 60-70F day.)

Still, I would expect (or at least hope) that if the machine is "really healthy", that it would gracefully fail if pushed too far, such as by the "overheat" LED indicator coming on and gracefully (and temporarily) shut down the welding output. I do have an aftermarket, high-amp torch on this machine by the way. I melted down and upgraded the factory WP-17 torch long ago. It is necessary to upgrade the torch to really utilize the output capacity of this machine.

I don't know if the goal of getting a graceful (and temporary) overtemp indicator shut-down is attainable, or shooting too high for this design of machine. I guess we'll see.

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Originally Posted by performance

Jakeru,
Considering that unit is as old as it is, and the issues that were faced with it, I'd say that the unit has held up well. I'm glad you had the skill to fix it quickly, and I dare say cheaply.

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Agreed, Mark. My machine has certainly proven itself to be reliable over the years I have used it, this is the first time it has actually broken down on me. I am very glad it was something I was able to take care of quickly. I also appreciate that it seems Everlast has always been there whenever I need them.

Although it's indeed a 4 year old machine at this point, I hope to keep it running for many more years to come. :cool:

Quote:

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Originally Posted by acourtjester

I hope you replaced the heat sink compound also for the thermal connection to the heat sink.

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Oh - I almost forgot. I did also find some spots where more than one layer of rubber electrical isolation sheeting was present behind some diode packages. (Including, guess which one? Yep, the diode package that failed / shorted out!)

Here is a picture of what I am talking about... two overlapping rubber sheets shown behind the failed diode, shown in the "as installed" position:
Attachment 2406

I figured that more than one rubber sheet can only hinder the thermal connection to the heat sink, so I removed the overlapping layers by trimming it with scissors / utility knife.) Here it is with the overlapping rubber sheet problem fixed:
Attachment 2405

Good tips, but there was no way I was sticking a solder sucker in where the chip was. Had to use a wick and plenty of flux. It worked out and it's working great again

which is exactly what I did :) I also ordered a few spares and a few more sockets in case this happens again to any of the other chips

What is the 4053? It does not seem to be an obvious part like a 393, 555, 7805, 8051, 741, 17hc14, etc.

CMOS multiplex IC. It's used to decode signals from the pedal to vary the amperage....among other things

Thanks. Do you have a link to where you ordered the chip from?

Update - following the diode board modification, my Super200P seems to be running stronger than ever!

I just finished a fairly thick aluminum TIG welding job, and although I was a little more cautious about exceeding the duty cycle (I actually gave it some time to rest and cool down here and there between wide open power weld beads in AC TIG welding mode), I believe I have achieved a new milestone: I got my ground cable nice and toasty warm.
http://www.everlastgenerators.com/fo...3588#post13588

Maybe it's time to upgrade the thickness of the ground cable. Or, maybe I should take this as a sign that it's finally time to spring for that extra gas bottle (to fill with some Helium for an extra kick of metal melting power.)

I still have yet to trip my 30A breaker while welding on this machine in TIG mode. It's a remarkably power efficient machine.

Jakeru,

The replacement part is a bit beefier if I recall. So you should be good. I did not even see this thread until it popped up today. Guess I was on the phone with you. Hahaha.. Excellent detail.

On 4053's Ray and I have stock, and it is not a big issue so they only go out if one died, at no charge, along with a sockets. So no need to panic there.

Also, Jakeru's unit is 4-5 years old and if you look at his post on the forum, he beats the tar out of it. :D

I did one of my machines in the winter, but the supplier of infineon mosfets expect you to buy a lot of 100 so I bought 2.Cost $10.00 cdn $25 for shipping and wire transfer.I love the fact that I know my machine better, I have electronic experience so I desoldered with flux and braid.Also added more heat transfer fliud to hest sink/I wonder though where the flaw is with the transistors, lack of testing or rough handling.Quite the experience when the transistor blows in use. Great article.

Sometimes in rough shipping a crack can occur by the legs pulling on the package. And sometime the units would run for a couple hours. Nature of electronics.

The new modules are like bricks so we do not see this much anymore as we only ship a couple discrete MOSFET units now and they are small and lighter, meaning they get dropped less in shipping if dropped at all.

Jakes article is great and the 200P is still a darn good unit (as he shows in his projects), just note we have made a lot of shipping changes and part upgrades in the last 3-4 years so his article only apply to the Super 200P and Super 250P units.

On a high power transistor going while in use, it's right up there with an over heated cap. Both will get your attention.

Hi

I was wondering if any one has some connection diagram or good internal photos so I can rebuild mine correctly.

Hi jakeru, I don't suppose you have any pictures from this thread? Seems the attachments are no longer present. Good work on your fix :).