1995 century 20 amp plasma cutter will trigger and air will activate, but no arc will be produced. If I touch tip to grounded area it wil "spark" but that is all.

Could be as simple as having the ground cable connection placed into the wrong port on the front of the machine. Foot peddle/machine selection switch in peddle mode instead of machine mode? Internally it could be high frequency spark leakage or failed HF circuitry. These are the most common causes of spark failure. Oh and be sure you have good consumables and they are installed correctly. Air pressure leaving the torch head should be around 70 psi.

sounds like the voltage is not getting to the tip. I would suggest taking this in for repair.

Contact Lincoln Electric. They bought out Century and can send you a copy of the manual via email.

Make sure you have a good ground. If ground is good, make sure you are holding the tip level to the work and right up close.

Check compressed air pressure is in limits otherwise unit will cut out. Try adjusting the pressure up. also make sure the supply pressure is correct as it may not be your plasma cutter at fault.

Possibly an internal short in the torch tip... the expendable components failing in the tip will cause the sensors in the machine to register a "no cut" or "free air arc" state and kill the power to the tip to prevent damage to the unit. Replace the tip components and double check the grounds connections.

Possible failure of the trigger switch and or the cable back to the unit. Use an ophmmeter to check that the trigger and cable are good,

Then with the ohmmeter check the continuityu of the cable to the electrodes,

Connectors are always suspect.

These are starting ponts to check.

the spark that you see when you touch work peice is high frequency,recheck connections like good ground (tight and clean)on the unit and work peice.no ground no fire.

If you have water in the system, bad tip or ground it wont spark properly
Domo

There are a few things about plasma cutting safety that are different from general welding safety tips This short list of plasma cutter safety tips is geared toward light duty plasma cutting using compressed air not large industrial units that use gas mixtures and water cutting tables. Electric Shock Can Kill - Operating a plasma cutter completes an electric circuit between the torch and the workpiece. The workpiece and anything touching the workpiece are part of the electrical circuit. - Never touch the torch body, workpiece or the water in a water table when the plasma system is operating. Voltages & Currents - Plasma cutter output voltages are much greater than welding voltages, usually 100-200 volts. Precautionary Measures - Do not pick up the workpiece, including the waste cutoff, while you cut. Leave the workpiece in place on the workbench with the work cable attached during the cutting process. - During plasma cutting operations do not move the work clamp. Wear insulated gloves and boots, and keep your body and clothing dry. - Do not stand, sit or lie on or otherwise touch any wet surface when using the plasma cutter system. - Insulate yourself from work and ground using dry insulating mats or covers big enough to prevent any physical contact with the work or ground. If you must work in or near a damp area, use extreme caution. Work Cable - Ensure metal-to-metal contact between work cable and workpiece or work table. - Work cable clamp should make contact with clean metal free of rust, dirt, painted surfaces, etc. - Do not attach work cable to the piece that will fall away when the cut is complete Plasma cutter Arc Rays Plasma cutter arc rays produce intense visible and invisible (ultraviolet and infrared) rays that can burn eyes and skin. Protective Clothing - Guantlet gloves, safety shoes and hat. - Flame-retardant clothing to cover all exposed areas. - Cuffless trousers to prevent entry of sparks and slag. - Remove combustibles, such as a butane lighter or matches, from your pockets before cutting. Noise Levels of Plasma Arc Cutting - Plasma arc cutting systems can generate noise levels in excess of 120 dB during high-amperage cutting operations. - Ear protection should be used when operating or working near plasma arc cutting operations. Toxic Fumes & Gases Plasma arc cutting can produce toxic fumes and gases that deplete oxygen and cause serious injury. - Keep the cutting area well ventilated or use an approved air-supplied respirator. - Do not cut in locations near degreasing, cleaning or spraying operations. The vapors from certain chlorinated solvents decompose to form phosgene gas when exposed to ultraviolet radiation. Pacemakers & Hearing Aids - Pacemaker and hearing aid operation can be affected by magnetic fields from high currents. Pacemaker and hearing aid wearers should consult a doctor before going near any plasma arc cutting and gouging operations Overall Plasma Safety - The plasma arc cutting process can be very safe. - By paying attention to safety standards and correctly setting up and operating the system, plasma arc cutting poses no more a threat than most welding processes.