Chinese Plasma Cutters

[inVERt'D]

Already planning Phase 2, eh? What's next, coilovers and links?

[jonah]

Ha ha, at least thinking about it if not planning! I guess I should concentrate on getting this one moving first. But, eventually I think I may go bigger axles/tires, keep the leaf springs (but move to a little lift spring from the stock YJs) I don't know if I really want to link an old CJ, and do a modern motor, or at least fuel injection for this one. I guess we will see how it does on the trail and see...

[jonah]

Oh yeah, I also want to dump the NP205 and adapt a dana300 or atlas if I find a little cash. then I could move the engine back a bit and fit a V8.

[inVERt'D]

Uh-huh... I'm betting the hood gets trimmed by Phase 3--any takers?

[jonah]

Hold on now, that is crazy talk!



unless it is in the way, cheers to monday :beer:

[inVERt'D]

Update - It went out with a bang

So about a week ago I plugged in my trusty plasma cutter to start making a stand for a sheet metal brake, flipped the switch, and *POP* (that was supposed to be a really loud POP coming from inside the box). That probably wasn't good, I thunk to myself as I unplugged it. I had probably thanked God every time the fandangled thing didn't blow up, so I can't say it was a complete surprise.

Upon inspection, I found damage to the power supply board. About 2" of copper tracing had been vaporized between a couple of relays. Could only find a direct replacement for one of those relays (although there are two others just like it elsewhere on the board), so I ordered me a set of 5 for $6.50. They're on their way from China now. Just for kicks I jumpered the tracing with a soldered-on wire, but the machine clicked once and hummed before I'd even flipped the switch. Not supposed to do that. Hoping the relay fixes it, but definitely not counting on it. I'm obviously not an electronics whiz, but I've always wanted to learn... wish me ruck.

When I bought the thing the plasma cutter was the main thing I was interested in. The TIG and stick functions were like bonuses. Since then, I've found the stick very handy when it wasn't convenient to use my big gas-powered Lincoln. I've become addicted to the DC TIG. I knew that the main downside of having a 3-In-1 setup was the liability of losing all three if the machine failed. With prices what they are nowadays, I would definitely buy the plasma cutter and TIG as separate machines.

[Materdaddy]

So about a week ago I plugged in my trusty plasma cutter to start making a stand for a sheet metal brake, flipped the switch, and *POP* (that was supposed to be a really loud POP coming from inside the box). That probably wasn't good, I thunk to myself as I unplugged it. I had probably thanked God every time the fandangled thing didn't blow up, so I can't say it was a complete surprise.

Upon inspection, I found damage to the power supply board. About 2" of copper tracing had been vaporized between a couple of relays. Could only find a direct replacement for one of those relays (although there are two others just like it elsewhere on the board), so I ordered me a set of 5 for $6.50. They're on their way from China now. Just for kicks I jumpered the tracing with a soldered-on wire, but the machine clicked once and hummed before I'd even flipped the switch. Not supposed to do that. Hoping the relay fixes it, but definitely not counting on it. I'm obviously not an electronics whiz, but I've always wanted to learn... wish me ruck.

When I bought the thing the plasma cutter was the main thing I was interested in. The TIG and stick functions were like bonuses. Since then, I've found the stick very handy when it wasn't convenient to use my big gas-powered Lincoln. I've become addicted to the DC TIG. I knew that the main downside of having a 3-In-1 setup was the liability of losing all three if the machine failed. With prices what they are nowadays, I would definitely buy the plasma cutter and TIG as separate machines.

Be very careful. The reason it buzzed when you tried jumping the trace was there were still capacitors with a charge in there. There's likely enough power in there to kill yourself. It only takes something like 10mA in the right place.

[RAT]

Be very careful. The reason it buzzed when you tried jumping the trace was there were still capacitors with a charge in there. There's likely enough power in there to kill yourself. It only takes something like 10mA in the right place.

I can see it now. The headlines read " Man killed by Chinese Plasma cutter". Public outcry leads to War against Chinese. Obama makes Executive Order that all previously confiscated and destroyed assault rifles be undestroyed in order for them to be used against the new "EVIL EMPIRE" ...

[Materdaddy]

I can see it now. The headlines read " Man killed by Chinese Plasma cutter". Public outcry leads to War against Chinese. Obama makes Executive Order that all previously confiscated and destroyed assault rifles be undestroyed in order for them to be used against the new "EVIL EMPIRE" ...

Ok Kurt, you've gotta turn off Fox news for at least 5 minutes a day... :hide:

[USMC 0369]

ok kurt, you've gotta turn off fox news for at least 5 minutes a day... :hide:

fair & balanced!!! Fair & balanced!!!





[ATTACH=CONFIG]1121[/ATTACH]

[inVERt'D]

Well, even if I had died stupidly, at least I wouldn't have died in vain. All the same, I think we'd have a better chance of straightening out Obama if he discharged the capacitors himself. Now pucker up, purple lips!

Matt, that's some good advice, thank you. There are 6 pretty healthy capacitors on that board, plus some smaller ones. Now that I've reread it, I realize the way I said it was misleading.. The humming didn't happen when I jumpered the tracing. I soldered a wire in place as a jumper, hooked the board up, and plugged the machine in. Then it hummed. I tried to discharge the caps by short circuiting a them with a screwdriver with a rubbery grip. That seemed uneventful, but I probably should have used something grounded for the machine's safety as well as my own.

Any further tips from someone who is or might be more knowledgeable about these things than me would be appreciated.

I got the relays today. A week and a half--pretty fast from China.

[Materdaddy]

Well, even if I had died stupidly, at least I wouldn't have died in vain. All the same, I think we'd have a better chance of straightening out Obama if he discharged the capacitors himself. Now pucker up, purple lips!

Matt, that's some good advice, thank you. There are 6 pretty healthy capacitors on that board, plus some smaller ones. Now that I've reread it, I realize the way I said it was misleading.. The humming didn't happen when I jumpered the tracing. I soldered a wire in place as a jumper, hooked the board up, and plugged the machine in. Then it hummed. I tried to discharge the caps by short circuiting a them with a screwdriver with a rubbery grip. That seemed uneventful, but I probably should have used something grounded for the machine's safety as well as my own.

Any further tips from someone who is or might be more knowledgeable about these things than me would be appreciated.

I got the relays today. A week and a half--pretty fast from China.

Jumping the tracing w/ a screwdriver could discharge them rather quickly, but would probably work. The safer bet would be use a resistor, but good luck finding a high enough powered resistor for the size of capacitors you're dealing with. Just be careful David!

Glad it was after plugging in, not when you were jumpering the vaporized trace for your safety. Hopefully the relays fix it up nicely for you!

[inVERt'D]

Thanks Matt, I'll keep ya'll posted

[inVERt'D]

Back From The Dead

Thank God, the Chinese Prasma Cutter is working again!

Short Version: Replacing the relay and jumpering the tracing with a wire did the trick. I'm very happy about this.

Long Version:

I had gotten as far as removing the dead relay; this meant removing some thick solder that was augmenting the tracing below directly below the relay. 1/4" carbide rotary file in die grinder worked great for that.

About that time, a friend came over needing his POS utility trailer fixed (falling apart and broken birdsh** welds everywhere). It had slipped my mind up to then that he's pretty good with electronics. Long story short, we agreed to trade some labor. The relays I had ordered came with an additional prong. He confirmed that this prong was only a neutral/ ground. He soldered in the relay for me, and re-jumpered the tracing, which I had removed.

Having no schematic, we tried to get power from the board without hooking it up to the other boards, but were unsuccessful. Finally, we ended up wiring it up completely. We said some prayers (at least I did), put on eye protection, and flipped the switch. The fan came on and electro-mechanical points clicked happily. So far so good. I tested the stick arc function first--it worked!. Next I tested the plasma cutting function. Was a bit concerned, because this function had been on when it went POP. More prayers. Put the amperage on low, and...couldn't start an arc. Turned up the amperage and got better ground. Still no love. The airgap had an arc, but it looked and sounded a bit weak, so I opened it up a bit. This airgap is just a pair of flimsily mounted copper points, and they'd been pushed closed by the time I'd gotten the board back. I'd already opened them up, but apparently not enough (where did I put my feeler gauges??). Well, this did the trick, and the plasma cutter worked again!

This airgap is worth taking note of if you have a Chinese machine. Compared to better machines, it's hokey and flimsey. Bumping it or even hitting it with compressed air can move it. I've had to clean and/or adjust it several times in the past to keep the plasma cutter working properly.

So what caused the problem in the first place? We still don't know. My friend did find one spot on another board which had a tiny bit of solder splatter between two close, but not otherwise connected soldered contacts. Perhaps some dust or moisture had closed it and made an accidental circuit? I've regularly blown the dust off the boards for exactly this reason. I'm going to confer with my friend about where to put a fuse or fuses to help prevent something as bad or worse from happening again.