Trimmer Ignition Coil – Faults And Repair

Lawn mowers are a popular seasonal tool designed to remove unnecessary vegetation in the house area. Like any other equipment, these devices periodically break down. Repairing the trimmer ignition coil is one of the most common problems encountered with gasoline braids. The ignition system itself is designed similarly on two- and four-stroke ICEs, so the elimination of breakdown is performed almost the same for tools from different manufacturers, whether it be Lux, Huter, Husqvarna or another brand. Ways to restore the efficiency of the ignition coil or replace it with a new one are in the material below.

Magneto. Design and concept of work

The purpose of the ignition coil is the conversion of rotational energy into a high voltage discharge and the formation of a spark igniting the fuel mixture. In an internal combustion engine, this part is called magneto, since in it an alternating current is generated from the rotation of a constant magnetic rotor or armature.

Trimmer Ignition Coil. Faults And Repair

Magneto constructively consists of two windings: high and low voltage. A capacitor with breaker contacts is connected in parallel to the latter. Whereas the findings of the high voltage winding are connected to the candle and the housing. Both of them are wound on a core, between the poles of which a rotating magnet is installed, magnetized longitudinally.

On a note! The whole design looks like a large coil mounted on a U-shaped core.

Health Check

Before you start diagnosing magneto, you need to make sure that the problem is actually in this node. To do this, you need to check the entire circuit and make sure that there are no other reasons for the failure of the trimmer.

  1. First you should carefully inspect reel for cracks and other external defects on the case. Next, you will need to examine all the elements and nodes that conduct current, and make sure that they are clean.
  2. The next step is inspection high voltage wires. They must be intact and securely attached to the contacts, free of rust and with intact insulation.
  3. The next step will be checking candle cap. As a result of careless actions, the user often tears it from the high-voltage wire, and then improvises and creates a makeshift mount. It must be understood that any poor-quality connection in this place significantly reduces the power of the electric arc of the candle.
  4. Then you should make sure that she candle good condition. If you fill the lawn with low quality gasoline, the life of this part is significantly reduced. In addition, it can be flooded or have a large soot that impedes work. Sometimes the candle even sticks and does not unscrew.
  5. Next, you need to inspect circuit breaker. On Chinese-made trimmers and chainsaws, it very often breaks.

Having completed all these steps and excluding the listed nodes from the list of possible causes of failure, you should proceed to checking the coil. This can be done in several ways.

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Method 1

The first way that the ignition coil is checked involves the use of special equipment (stand). At home, it is not available. You can find it only in service centers.

Method 2

Diagnostics of magneto using a multimeter is a solution that can be implemented on their own with such a measuring device. In this case, you must do the following.

  1. Switch on the resistance mode on the measuring device and set the value to 200 Ohm to test the primary winding.
  2. Connect the electrodes of the multimeter to the “mass” of the magneto and the output contact. If the winding is intact, the resistance will vary from 0.4 to 2 ohms.
  3. Turn on the 20-com tester to perform secondary winding diagnostics. In this case, the first probe is connected to the “mass”, and the second is installed in the candle cap. Normal values ​​are at least 4-6 com. If the circuit is damaged, then the tester will show infinity, and in the case of a short circuit. Zero.

The exact data on what the tester should be during the verification of the primary and secondary windings can be found in the instructions for using the trimmer.

Method 3

If there is no multimeter, you can check the coil in one more way.

Important! The check must be carried out carefully so that the magneto does not burn out. For this, it is important not to touch the cylinder with an electrode.

For diagnosis, you need to perform the following steps:

  • Open the cover with which the cylinder is closed;
  • Remove the cap of the high-voltage wire from the candle without unscrewing the part itself to maintain compression;
  • Tightly place the nail in the cap without a hat, it will imitate the central electrode of the candle;
  • Bind the cap with a nail to the cylinder with a dielectric material so that the gap between the candle electrode simulator and the mass fluctuates from 5.5 to 7 mm (it is recommended to see the exact distance for a specific model in the user manual), but the part does not come into contact with the mass;
  • Starter several times to start the engine, holding the ignition button in the on position;
  • If a spark appears, you need to consider what color it is.

A white or bluish powerful spark is normal, and a faint glimmer of an orange or yellow hue indicates a broken coil.

Often, cold magneto creates a powerful spark, but when heated due to a defect in the internal components, it does not conduct current. After cooling, the lawn mowing coils start up again and mow the grass with a fishing line or knife before heating the magneto. This is abnormal behavior, so the coil needs to be changed.

On a note! Similarly, the problem can occur when the candle is heated and cooled, so it is recommended to check the operability of both parts.

Common Problems. Causes

Faults that most often occur with magneto are typical of trimmers from different manufacturers. As a rule, this is a weak spark or its absence, as well as interruptions in this process.

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Unstable sparking

If magneto flickers intermittently, check first contacts. They could be burnt or oily. Detected carbon deposits are cleaned with a file, and the oil is rubbed with suede, previously soaked in gasoline. The second possible cause of the problem is misregistration. Clearance between contacts. To eliminate it, you need to set the correct distance.

If the spark appears intermittently, it may also mean that breaker lever pad worn out. To eliminate the malfunction, it is necessary to change the lever to a new one. In addition, you should adjust the gap, as with another possible cause of failure. Adjust the outline.

Breaking through capacitor may also be responsible for interruptions in spark formation. In such a situation, the replacement of the damaged part is required, since it is impossible to repair and recharge it.

Lack of sparking

If magneto does not give off a spark at all, the main reason is breakage of one of the transformer circuits (primary or secondary). To repair the lawn mow, the defective part must be replaced. If happened primary circuit short to ground, it can also cause a lack of spark. You need to fix it to fix the problem.

On a note! The broken insulation of the high voltage wire can also cause breakdowns. You can correct the situation by replacing the wiring.

Lack of sparking

A faint spark on magneto is caused by a damaged capacitor. To eliminate the breakdown, it is necessary to replace the failed part.

DIY troubleshooting

In order to repair a magneto with your own hands without the involvement of specialists, you need to know how to disassemble it, and how to change the breaker contacts to new ones.

Magneto disassembly

Dismantling a magneto is very simple. First you need to remove this device from the engine and clean it, eliminating oil particles and dirt. Further, since the ignition timing unit is securely fixed, you need to unscrew the nut, and then remove the part and pull the key out of the groove. The cover is fixed on four screws. To remove it, it is necessary to unscrew and remove the fasteners. Then you need to remove the magneto rotor from the housing, unscrew the studs holding the transformer, and remove it. And to collect magneto, you need to perform the above steps in reverse order.

Replacing breaker contacts

After disassembling the magneto, it is necessary to remove the old contacts of the breaker and install the new ones correctly. To implement this, you must:

  1. Move the latch, remove the cover from the breaker;
  2. Unscrew the screw holding the connecting conductor;
  3. Remove the screw securing the breaker plate to the magneto cover and remove it;
  4. To get the screw fixing a breaker spring;
  5. Remove the lock washer from the axis, and then the lever with the pillow assembly that it holds;
  6. Unscrew the screw securing the contact pole, remove the part from the axis.

Assemble a node with new contacts in the reverse order.

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On a note! Despite the simplicity of the operation, most owners of trimmers prefer to simply replace the magneto with a new one.

Magneto Replacement

Advice! Another good solution would be to provide an old ignition coil so that the seller can pick up a new part.

To remove magneto, you need to remove the plastic casing from the trimmer. On different models of lawn mowing, this process is different. Usually it is necessary to unscrew the bolts, but some gas trimmers may need to release the latches. After that, access to the coil is opened. To remove the part, unscrew the retaining fasteners and disconnect the wires.

When installing a new part, you need to competently set distance between flywheel and magneto. To do this, turn the flywheel with the magnets up, install the coil and fasten it, but do not fully tighten the screws so that there is a small distance between the parts. Next, between the coil and the flywheel, you need to put a pocket calendar, a business card or a folded four-fold A4 paper sheet, you can also use a plastic strip cut from a bottle. Such tricks will provide a suitable gap between the flywheel and magneto. A more competent solution would be to use a special template, but to acquire it for the sake of one time is impractical. Next, you need to tighten the fasteners, remove the object located between the parts, and, holding the magneto with your hands so that it does not spin, tighten the fixing screws tightly. After this, turn the flywheel and make sure that it does not catch the coil anywhere. Now you need to connect the wires and insert the candle into the cap, and then check the operation of the device.

Problem prevention

Often, breakdowns of ignition coils are associated with a short or open winding and mechanical damage to the magneto body. This is due to strong shocks, fluid and oxidation, as well as overheating. If such incidents are avoided, there is no need to worry about the integrity of the ignition coil.

Important! To prevent the regular failure of candles. One of the most important components of the ignition system. You need to refuel high-quality fuel. Bad fuel spoils these parts.

One of the magneto nodes that regularly suffer during use is high-voltage wires, through which current is supplied to the spark plugs from the ignition module. They have a high service life, but users themselves cause damage to them by inaccurate handling when replacing candles, inadvertently pulling on the wire itself, and not on the tip. Another problem that can occur with them is moisture and oxidation or damage to the insulation. By carefully pulling out the candle and avoiding the ingress of liquid into the device, these problems can be avoided.

So, the repair of the ignition coil is not very difficult and can be carried out by the user independently, but subject to the above procedure for disassembling and replacing the magneto or the breaker contacts.