Exceptions aside, it is often easier to carry out maintenance of a plasma cutter than to fix problems, but a combination of chance damage, rigorous use and bad luck can lead to problems in the long run since different product components have different life cycles and some tend to wear out faster than others.
While exterior components like electrodes and grounding clamps can be replaced with ease, some others like diodes, air pressure hoses and a range of other small and slender internal components. Some of the repairs are best left to professionals, but there is no reason why you can’t try troubleshooting plasma cutter problems yourself.
Problems with Air Hose
Attached to the torch is a long tubular air hose that acts as a conduit for high pressure air or gas. Contrary to what many repairmen claim, the hose is not a special heat-resistant one since there is virtually no heat to deal with before the arc hits the oncoming air/gas stream. Before one carries out any corrections though, it is necessary to know the exact problems involved. To diagnose the problems, you need to:
- Start the air compressor and the cutter.
- The best plasma cutters have a dial for selecting the amperage. Set this dial to maximum.
- Take careful note of the morphology of the hose and torch. If a little air is getting through, you would get a faint arc, while if no air is getting through, nothing will happen. Further, note if a certain part of the hose begins to swell up.
- If there is little or no arc being produced but no bulge appears in the hose, either the connectors are not working properly or the air compressor is at fault. Fixing the air compressor is a complex process that requires professional help. However, if you find that the compressor is working normally but the arc still doesn’t appear, you can simply shut down the machine, remove the connectors and try on new ones to see if they work. Look for broken or rusted hinges as these often cause air to leak out. Trying out the new connectors is a similar process to that mentioned above and when the arc appears again, you are ready to start cutting again.
- If there is a bulge being produced, you would need to change the hose, regardless of whether you’re using your dad’s unit or one of the best plasma cutters on the market.
- Remove the torch from one end and the connectors from the other. Now carefully unhinge the torch from the hose, ensuring that the electrical parts are not damaged. Sometimes a wire or two may need to be cut and before taking this step, you should ensure that you have adequate soldering equipment at home.
- Once the connector and torch are disconnected, press down along the length of the hose to allow residual gases to move out. Now cut the outer protective layer lengthwise. If you cut carefully enough and know how to use a plasma cutter well, you can reuse the cut cover with black electrician’s tape without putting yourself at risk of receiving a blast of compressed air/gas from the hose. In such a circumstance, do not discard the outer covering.
- Before you actually get down to troubleshooting common plasma cutter problems like this one, you need to remove the interior covering as well. Sadly, this covering cannot be reused and will need to be discarded.
- Once this is done, you should have a normal hose in your hand. Investigate the entire length for signs of damage, breakage, stretching or (rarely) blockage.
- If a blockage has occurred or the stretching can be reversed, alleviate the problem by either passing water at high pressure (for blockage) or leaving the hose in cold temperature and in coiled position for the night (for stretching).
- Never attempt to repair breakages. Instead, take the hose to a hardware store and get a replacement.
- Wrap up the hose in electrical shrink tape and wrap the outer covering or zippered TIG welding cable to obtain the necessary protection.
- Reattach the torch and connectors and test the hose.
Problems with Diodes or Resistors
More complex are problems with diodes, resistors or more rarely, capacitors. While each product has a different assembly, the essentials are generally the same. Keeping the average unit in mind, we’ve compiled the following steps for troubleshooting plasma cutter problems associated with the internal circuitry:
- Disconnect all power connectors and the hose connector and leave the unit undisturbed for some time. Alternatively, use a discharging cable to remove residual electricity from the unit.
- Take note of all the resistors, diodes and capacitors and note their capacities. Also, take note of their positioning to ensure that you do not end up mixing up the positions later on.
- Use a multi-meter to measure the potential/resistance/capacitance of each component and compare it with the marked values. Usually one or more of the parts will show wrong values and these can then be removed.
- Replacing the resistors is easy but you may have to use multiple diodes or capacitors in series to achieve the capacitance or potential of a single malfunctioning component. While doing so, make sure that the impedance of the units are taken into account as well, since two components of the same type and value but with different branding may have different impedances.
- Once you’ve connected the components, set the cutter to the lowest setting.
- Put on required safety equipment and remove the torch from the hose. Now connect the power supply and use the hose as you normally would. Note whether air is coming out of the hose. If it is, the connections are correct.
- Turn off the unit, remove connectors and replace the cover. Reinsert the connectors and the torch and run the unit as you normally would.
Note : Never open the unit’s casing until all connectors have been removed.
Not every part of the cutter lends itself to troubleshooting plasma cutter problems and one has to accept that professional help may be required when problems arise in these areas. However, given that the connectors, hose and resistors, Capacitors, etc. are the most rigorously used internal components, it is likely that a majority of issues will involve one or more of these parts. Knowing the above procedures, you can save money and the time required for the professionals to return the unit with the necessary changes.