Esab PCM-750 plasma keeps blowing fuses?

[greenbuggy]

Trying to get this figured out. Couple years ago I bought this plasma, put quite a bit of use on it. Last winter the pilot arc was getting progressively weaker so I replaced the two puck resistors as suggested by an esab tech. Last couple times I've used it the pilot arc works when I start but blows the fuse in <5 mins of usage. Consumables are all within spec, not brand new but not more than 20 mins cut time on them either arc is still tight thru the orifice. Any ideas why it would be doing this?

[ccawgc]

We can try several things. First make sure you have a 12 amp pilot arc fuse.
Second get a ohm meter and measure the new pilot arc resister make sure it is 6 ohms.
Third if you have or can borrow a clamp on amp meter. measure the pilot arc current. make sure it is less than 12 amps.
forth, double check your air pressure. make sure it is set right, to high or to low cause cutting and torch problems. High pressure will blow the arc out and ware the consumables fast. Low pressure can over heat the torch head.
When you measure the pilot current, turn the control knob up and down, see if it changes.
Current should not go up until the torch is cutting. You need a feed back signal from the shunt to cause the control pcb to switch out of pilot. Check the pilot relay and make sure it is not stuck closed. If it is stuck closed some of the cut current goes through the pilot circuit.
It needs to open just as soon as the torch starts cutting. Get a buddy to watch it while you cut. Good luck