Resurrecting a dead plasma cutter...

[tomrscott]

I have an "opportunity" to pick up a Hypertherm 600 in very clean condition - except - it isn't working. /forums/images/graemlins/frown.gif

A service shop who looked at it said the torch works fine and it just needs the circuit board repaired/replaced. I've seen the circuit board and it is very clean but has a couple diodes that got fried, probably in the input or output. I can "finnagle" this unit for next to nothing $.

I have 25 years in electronics, so I'm not at all intimidated about tearing into a circuit board, but that is not to say there can't be something wrong that I can't fix, but the odds are probably fair that it is something simple that I can fix. If I cannot fix it, I could pay to have the board repaired by a third party shop who does these, or even buy a new board from Hypertherm and still be way ahead.

Here's the rub: Apparently plasma cutter manufacturer's don't provide any service information for the circuit board level, all they will do is swap out the board. I guess maybe they consider this a liability issue, however this is not a very complicated circuit board. There are third party shops who apparently will repair these boards for about half the cost of a new board, but I guess they're on their own too. Worst case, if a proprietary part like a microprocessor got fried, I might have to buy a new board from Hypertherm.

This is obviously a bit of a "pig in a poke", but I'm feeling lucky /forums/images/graemlins/wink.gif and even if I had to buy a new circuit board from Hypertherm it would still be a pretty good deal. If I can repair it, it's a "smokin' deal!"

1) (very long shot) Does anybody know anyone with connections to get circuit documentation for this unit? I can poke around without a schematic or parts list, but it's a lot easier with the proper documentation. I will check with the factory tomorrow, but from what I gather, they don't readily give this out. Maybe they used to? And maybe someone has something from an early or similar unit? Never know till you ask.

2) Does anyone have a Hypertherm 600 who would be willing to look at the components on their circuit board and read a part number from it if something is illegibly charred on this one?

With a bit of luck, I might be cutting out tractor weights in a week or two. /forums/images/graemlins/wink.gif

Call me nuts, but I have a good feeling about this. I'll let you know how it turns out.

 

[BGL990]

I'm an electronics geek as well (by training and by hobby) and I wouldn't even think twice. GRAB IT!! A couple smoked diodes is probably no big deal. If they are zeners it might be a bit of a challenge to figure out their voltage rating, but if they appear to be rectifier or signal diodes and you can guess at their proper orientation, just substitute something generic (1N4148 or 1N4000 series) and see what happens.

 

[WhiteRock]

Plasma cutters are great machines. I can understand the desire to get one at a good deal. They are quite expensive.

If I were paying very much for it, I would go in with the assumption that Hypertherm service/cost will be required. If you come out better, great.

This sounds like a recent Hypertherm model. Hyperthem appears to put a lot of engineering into their machines and I think you will find this board to be fairly sophisticated. Not that it can't be fixed, but it will be a high current regulated DC power supply. When the cutting process starts the power supply will attempt to maintain a high current flow. This means the voltage will be raised to maintain the start current. I don't know what the max voltage can go to, but BE CAREFUL. I suspect there can be some voltage there that can hurt.

The other problem I suspect you may face is the use of fairly expensive MOSFET devices for the high current regulated output. If you do not get all the bad parts replaced in the first attempt, you risk blowing another one of these expensive parts during test. On top of all this, they may use proprietary devices in their power supply to protect their competitive advantage.

I don't want to discourage you, but these might be some things you want to consider. I would do for the right price.

 

[PineRidge]

I'de grab it up in a heartbeat. After all even if you don't want it someone else would at eBay so it's a no lose situation if you can get it real cheap.

As far as printed circuit boards are concerned I know where you're coming from. We used to be a Bryant Dealer. Carrier and Bryant are one and the same. Whenever there was a problem with a circuit board and there were many, we could only get the complete board. The majority of the time it was a cold solder joint or a single fried component but the boards were treated as a throw-away replacement item.

Then again how many times do you ever remember seeing a computer technician carrying around a soldering iron for his repairs?

TC-40D SS web pictures click here

 

[bobodu]

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Then again how many times do you ever remember seeing a computer technician carrying around a soldering iron for his repairs?
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Too funny!! I think I have 5 computers that I built living here.I have one soldering iron...wonder where it is...... /forums/images/graemlins/confused.gif

 

[dummy]

What's the cost of a replacement cca? Some of the one's we use are much cheaper to buy than repair.

 

[slowzuki]

I have a Hypertherm 600, I would look inside if it didn't void my warantee... I would snatch it up, a new torch is over 600$ Canadian alone /forums/images/graemlins/shocked.gif

 

[aardvark]

I'm actually designing a throw away product right now. It's manufacturing cost is low enough, that paying our warranty dept to fix a return would cost more than just sending a new one. This product is going to be pretty neat. Two plastic housings, a couple connectors, two labels, and that's it. No screws, no seals, no test ports, nothing! Just going to sonic weld the housings together, and it's done!

 

[WhiteRock]

Sounds pretty neat. Do you mean a throw away plasma cutter?

Care to elaborate on the electrical stuff works? Would be interesting.

Thanks.

 

[TWINKLE_TOES]

Tom, if you don't see any fine pitch devices (25mil centers on leads) no IC's with Software version numbers tapped on the top or with little windows. If the circuit board is not more than two layers, If it's all discretes- R's C's Transistors (bipolar or FET) No larger geometry parts (2" x 2" epoxy blocks -IGBT's/SCRs) Part marking with established manufactuers(TI, National, Farchild, etc.) No custom magnetics then you can probably fix it. I would take a chance. If not the line starts at the street for guy's that are willing to try and I wanna be first in line.