How to Put the Ignition Coil On a Trimmer Correctly

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 breakage 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.

How to Put the Ignition Coil On a Trimmer Correctly

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.

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.

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.
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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.

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 (the exact distance for a particular model is recommended to see 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.

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.

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.

Video: How to Put the Ignition Coil On a Trimmer Correctly


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 must fix it to fix the problem.

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 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.

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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 spring of a breaker;
  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.

Magneto Replacement

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 secure 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.

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.

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How to connect a coil

The ignition coil is a transformer whose operation is aimed at increasing direct current. Its main task is the generation of high-voltage current, without which the arson of the fuel mixture is not possible. The current from the battery enters the primary winding. It consists of one hundred or more turns of copper wire, which is insulated with a special substance. A low-voltage voltage (twelve volts) is supplied to the edges. The edges are connected to the contacts on its cover. On the secondary, the number of turns is much larger (up to thirty thousand) and the wire is much thinner. On the secondary, a high voltage is created (from twenty-five to thirty thousand volts) due to the thickness and number of turns.

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It is connected as follows: the secondary circuit contact is connected to the primary negative terminal, and the second winding contact is connected to the neutral terminal on the cover, this wire is the high voltage transmitter. A high voltage wire is connected to this terminal, the other end of which is connected to the neutral terminal on the cover. To create a large magnetic field, an iron core is located between the windings. The secondary winding is located inside the primary.

Structurally, the ignition coil consists of the following elements:

  • Insulator;
  • Housing;
  • Insulating paper;
  • Winding (primary and secondary);
  • Insulation material between windings;
  • Primary winding terminal;
  • Pin screw;
  • The terminal is central;
  • Cap;
  • Output terminal on the primary and secondary windings;
  • Spring central terminal;
  • Primary winding frame;
  • External insulation on the primary winding;
  • Mounting bracket;
  • External magnetic core and core.

So, briefly about the principle of work.

A high voltage current arises on the secondary winding, and at this moment a low current passes on the primary. Thus, a magnetic field arises, as a result of which a high voltage current pulse appears on the secondary winding. At the moment when it is necessary to create a spark, the contacts of the ignition interrupter open, and at this moment the circuit on the primary winding opens. A high voltage current is supplied to the central contact of the lid and rushes into the contact near which the slider is located.

When connecting the coil to the ignition system of the car, in principle, you should not have any difficulties in the case when during the preliminary dismantling you indicated or remembered which wires are connected to where. If you have not done so, then I will tell you how to do it. The connection is as follows: the brown wire must be connected to the positive terminal. Usually, the positive terminal is indicated by “”, but if you do not observe the sign, then you need to find it yourself. You can use an indicator screwdriver for this. I think that you know how to use it. It is important that before connecting, clean all the contacts and check the wires for proper operation. The black terminal is connected to the second terminal (terminal “K”). This wire is connected to a voltage distributor (distributor).

A diagram of a bunch of several elements is as follows. One of the coil ends is connected to the on-board network. The second end connects to the next, and thus connects each to the last. The remaining free contact of the last coil must be connected to the distributor. And a common point is connected to the voltage switch. After all the fixing bolts and nuts are tightened, the replacement can be considered completed.

A few important tips before replacing and connecting. In the case when you have determined for yourself that the coil is the problem of the ignition malfunction, it is best to immediately purchase a new one and connect it (the circuit is indicated above). So you will be sure that now there are no problems with it, since it is completely new.

If you find some defects on the surface, it is better to replace it immediately. Otherwise, it will work for some more time and you will again have to return to this topic. It is better to play it safe in advance so as not to stop somewhere on the road. After all, ignition of a car requires not forgiving mistakes and negligence.

During car repairs, especially when it comes to the ignition system, you must be extremely careful in actions. Since you can run into high voltage wires. Therefore, when replacing or performing repairs, safety precautions must be observed.

Video “Ignition Coil Connection Diagram”

The recording shows how you can independently connect the coil.