Troubleshooting a plasma cutter
Esab 550. I had cut three holes in 1/4" plate when it just stopped cutting in
mid-stream. No spark. I checked the consumables, they're all new. I still get air when I hit the trigger. The overheat light isn't on. It still doesn't work the next day. I checked continuity of the power cable with an ohm meter and it has continuity, almost zero resistance. Is there some other way to test it? Could it have continuity at rest but fail under load? The trigger wires obviously have continuity because the trigger still works the solenoid valve to supply air to the torch. It just won't cut anything. The book suggests replacing the HF unit. How can I test the HF unit and what kind of money are we talking about to replace it? -- Jack |
Troubleshooting a plasma cutter
I'm not familiar with the Esab 550. Some other manufacturers models
have a pressure switch which will only allow an arc if air pressure is present. If that switch goes bad you won't be able to initiate an arc. Easy test is to jumper the switch. |
Troubleshooting a plasma cutter
On 16 Apr 2006 10:55:10 -0700, "Lefty" wrote:
Easy test is to jumper the switch. I'll try that first thing in the morning. Thanks. -- Jack Posted Via Usenet.com Premium Usenet Newsgroup Services ---------------------------------------------------------- ** SPEED ** RETENTION ** COMPLETION ** ANONYMITY ** ---------------------------------------------------------- http://www.usenet.com |
Troubleshooting a plasma cutter
Search google for high frequency arc starter. Sorry I don't have any
links, there on my other computer that is currently down. However, there are a couple of sites that show you how to build one. Also, look up Tesla spark gaps, same thing same parts. HF is commonly used with tig welding and also tesla coil people. I only have experience with older welders and plasma cutters. This means no solid state HF stuff. I'm no electronic expert, however I have fixed three HF circuits (which really means I simply changed out the capacitor). An HF circuit has basically three things: 1) step up transformer, 2) high voltage capacitor, and 3) an air inductance coil. The only thing that can really go wrong is that the capacitor goes bad. It seems to be a common problem. Test the capacitor (it will look like either a small hockey puck (called a doorknob capacitor), or like a rectangular block about ..5"Wx2"Lx1"D. I buy mines off ebay for about $10 to $20 each). Again search for high voltage capacitor or tesla. Aloha, Russell |
Troubleshooting a plasma cutter
On Sun, 16 Apr 2006 18:04:56 -0400, Jack Hunt wrote:
On 16 Apr 2006 10:55:10 -0700, "Lefty" wrote: Easy test is to jumper the switch. I'll try that first thing in the morning. Thanks. I can't find instructions listed, "650" is not a complete model number, is it...? If you don't have the instructions, try looking them up at www.esab.com - they might have a troubleshooting flow chart in the back of the book that will lead you right to the problem. Either that, or you find out you did something seriously wrong. Failing that, you open it up (carefully!) and look. Make sure there are no popped fuses, any safety switches (like the air pressure failure switch mentioned above) are working properly. As in, connect an ohm-meter across the contacts, apply air to the inlet as a function test, and see what happens. And make sure the supply air pressure is high enough - if the safety is set to cut out below 50 PSI, you have to be running over that point... DO NOT jumper switches or safeties randomly while you try to run the machine unless you are sure of what you're doing, and you are sure that the air pressure is in fact there - there is a good reason why the safeties were put in there. If it wasn't totally blown before, it will be after you jump the safety... And you look and sniff for any components that have "gone all melty." You'd be surprised how obvious that is sometimes... -- Bruce -- -- Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop Electrician for Westend Electric - CA726700 5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545 Spamtrapped address: Remove the python and the invalid, and use a net. |
Troubleshooting a plasma cutter
Jack Hunt wrote:
On 16 Apr 2006 10:55:10 -0700, "Lefty" wrote: Easy test is to jumper the switch. I'll try that first thing in the morning. Thanks. What he said. I once "fixed" a plasma cutter by telling the machinist to turn up the air pressure to it (: |
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