DIY repair of LMM Makita 9565

In detail: do-it-yourself repair of LMM Makita 9565 from a real master for the site my.housecope.com.

The grinder, being the most demanded tool in the house, is subject to considerable stress and intensive use. Because of this, after some time, it happens that when the engine is started, jerks, a burning smell and other malfunctions appear, suggesting that the angle grinder (angle grinder) has broken down. But do not immediately carry the device for repair or buy a new one. Most faults in this device can be rectified by yourself.

Over the long years of the existence of such a tool as angle grinder, its appearance, as well as its internal structure, have practically not changed. To repair a grinder with your own hands, you need to know the structure of its mechanical part, as well as electrical.

If you look at the figure below, you can see what parts the angle grinder consists of.

Wheel for adjusting the spindle speed of the unit.
An electric motor consisting of a rotor and a stator.
Start button. Sometimes a soft start system is connected to it.
High impact plastic housing.
Spindle lock button (used when changing tools).
Safety clutch. Protects the motor from overload when the tool is jammed.
Protective cover. Covers the tool and protects the user from escaping particles of the processed material, and also prevents injury to a person when a tool is destroyed, such as an abrasive disc.
Tool clamping nut. It can be unscrewed using a special key that comes with the power tool. There are also quick-locking nuts that can be unscrewed without a wrench.
The gearbox housing and the gearbox itself. Consists of a block of gears that transmit rotational movements from the rotor to the spindle with the tool.

Video (click to play).

The picture below shows electric diagram of the grinder.

The electrical part of the angle grinder has the following elements:

an electric cable with a plug for connecting to the mains;
start button;
stator;
electric brushes (carbon or graphite);
collector;
anchor (rotor).

The following figure shows grinder connection diagram, namely its engine.

All components of an electric motor perform specific functions.

Rotor - this is the shaft on which the coils and the collector are located. The rotor, rotating in the magnetic field of the stator, transmits the rotational motion to the angle grinder.
Collector... It is the part of the rotor to which all control cables are connected. Electrical signals from the control unit to the engine pass through the manifold. It is to the collector that the electric brushes are connected.
Electric brushes. Their main task is to transfer electric current from the power cable to the collector.
Stator. It is a coil with a certain number of turns. The task of the stator is to create a magnetic field, which, interacting with the armature, sets the latter in motion.

According to statistics, most cases of failure of angle grinders are associated with the electrical part of the apparatus. Some breakdowns may be minor, which allows you to repair the grinder yourself. But, for example, if the motor windings burn out, only a specialist can repair the angle grinder.

The reasons that the angle grinder does not turn on may be the following:

defective electrical plug;
defective electrical cable;
the start button has broken;
broken contact between the power cable and the button;
breakage of the contact wire of the electric brush;
strong wear of the electric brushes;
failure of the rotor or stator windings.

There may be different reasons for the angle grinder not picking up speed.

Breakage of the speed control unit... To test this version, it is necessary to connect the engine of the device directly, bypassing the regulator, and check the operation of the device.
Faulty electrical cable due to constant bending or mechanical damage. Because of this, the damaged wire begins to warm up under load, and the engine speed drops.
Dust contamination of the collector... Remove contamination with alcohol.
Brush problems... They may wear out or have a short contact wire, as shown in the following photo.

The brush, although half worn out, is quite functional. In this case, the short contact wire prevents the spring from pressing the electrode against the collector. This situation can also be the reason why the angle grinder stopped working in normal mode.

The reasons why the grinder is heating may be as follows.

Incorrect mode of operation of the device... As a result of overloads, the electric motor can become very hot, which often leads to burnout of the windings.
Bearing failurelocated at anchor. As a result, the rotor clings to the stator, the motor becomes difficult to operate, and the windings overheat. The problem is solved by replacing the bearings.
Clogged ventilation ductsthrough which air enters to cool the engine. It is necessary to clean the ventilation openings from dust.

Impeller breakage, which serves to cool the engine. It is installed on the rotor, on the side opposite to the collector. If the impeller is broken, it must be replaced with a new one.

Image - DIY repair of grinder makita 9565

Turn-to-turn closures stator and rotor windings. You will need to rewind the coils or replace these parts with new ones.

If you notice strong sparking when turning on the angle grinder in the place where the collector is located, then the reasons for this trouble may be as follows.

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To diagnose the electrical part of the angle grinder, as well as eliminate mechanical damage to the device, you will need to disassemble it. Disassembly is carried out according to the following algorithm.

Unscrew the handle.

Remove the protective cover.

Open the special windows located on the sides of the angle grinder casing and remove the electric brushes after disconnecting the terminals.

Unscrew the gearbox housing from the LBM motor housing.

Pull lightly on the gear housing and detach it from the housing. In this case, the gear unit will be removed together with the rotor.

After removing the armature, the motor stator will remain in the casing, which is also easily removed for diagnostics after unscrewing the fasteners.

To disassemble the gearbox, unscrew the screws holding the cover. Removing the cover reveals the gears of the reducer.

To remove the anchor from the grinder, you will need to unscrew the nut located inside the gearbox.

In order to remove the bearing from the armature, it is recommended to use a special puller. Otherwise, the shaft could be damaged.

As mentioned above, most often the angle grinder refuses to work due to breakdowns in the electrical part of the unit. For the correct diagnosis of the electrical circuits of the instrument, the repairmen of electrical equipment use a special device - tester.

If you pressed the start button of the unit and it does not work, then in 90% of cases the cause of the breakdown is not so serious that you cannot repair the grinder yourself.

Experts advise adhering to the basic rule of repairing a power tool: move from simple to complex.

The first step is to checking electrical cable and plug at its end. If it is collapsible, then unscrew it and check the reliability of the contacts.Otherwise, you will have to disassemble the grinder (remove the cover of the device) and “ring” the cable with a tester, and also make sure that the current goes to the contacts of the “Start” button. If the device shows a break, then the cable should be replaced with a new one.

The situation when the current flows to the button, but does not pass further (when the position is on), indicates switch malfunctions... The button cannot be repaired. It must be replaced with a new one, but first mark the removed contacts in order to connect them correctly in the future. If the contacts are incorrectly connected, the motor winding may burn out.

If during the check it turned out that both the cable and the start button are in good order, but no current flows to the brushes, then it is necessary to make cleaning the contact plates of the brush holders... If this procedure is ineffective, it is recommended to replace the brushes. Further, if everything is fine with the brushes, and the current flows to them, the rotor and stator should be checked for shorts and breaks.

The rotor of the electric motor may have the following malfunctions: interturn short circuit and wire breakage at the contacts of the lamellas. You can check the grinder's anchor with a multimeter: the device is switched to the resistance change mode, the value is set to 200 Ohm, and the resistance between two adjacent lamellas is measured with the help of probes. Thus, it is required to check all pairs of lamellas. If the resistance values are the same, then the rotor winding is not damaged. The detection of other resistance values during the “ringing out”, as well as the detection of an open circuit, indicates a malfunction in this coil. In this case, you will need to repair the grinder's anchor.

Usually, the rupture of conductors occurs at the junction with the winding. Inspect the places where the coils are connected to the lamellas, make sure that the soldering of the contacts is secure.

If you do not have a measuring device, then you can check the rotor by using 12 V light bulb and battery... The power should be between 30-40 watts. The check is done as follows: apply a voltage of 12 V from the battery to the plug of the angle grinder, connect a light bulb to the break of one wire, start rotating the spindle of the angle grinder. If the winding is in good condition, the light will burn evenly, without blinking. With an inter-turn closure, the degree of incandescence of the spiral of the light bulb will change. In this case, repairing the grinder's anchor with your own hands will be difficult, since the anchor winding scheme is quite complicated, and the process itself requires special equipment and knowledge. Therefore, it is recommended to entrust this operation to specialists. But the best way out of the situation would be to replace the anchor on the grinder with a new one.

If the light does not light up when testing the rotor, this indicates the presence of an open in the stator or a short circuit in its windings, as well as problems with the electric brushes.

To check the stator of the grinder, use, as in the previous case, a multimeter. The values you need set to 20-200 Ohm and do the following. Touch one probe to the contact of the stator winding, and the second to the body of the part. If the device shows resistance, it means that there has been a breakdown to the case. Touch the probes to the contacts of one winding, and then to the contacts of the other. If the resistance is the same, then the coils are serviceable. If the device shows an open circuit on one winding, it means that you will need to rewind the stator or replace the part with a new one.

It will be problematic to rewind the stator at home without special knowledge, skills and equipment. It is better to contact a specialist who is professionally engaged in motor rewinding.

Mechanical breakdowns of angle grinders include the following.

Mechanical failures include breakage of the shaft retainer. In order to replace the retainer, you will need to disassemble the gearbox and remove the large gear.

Most of the tools used on the farm are not insured against breakage. The grinders, which almost every master has, fail over time. Different models of angle grinders may have a similar type of malfunction. But each brand has its own characteristics in design and components.The renowned Makita brand is valued for its high quality - durability. However, devices of this brand also tend to break. Image - DIY repair of grinder makita 9565

Repairs can be done at home. Spare parts for the machine can be easily purchased. Before repairing the device, you must familiarize yourself with the attached diagram.

Types of angle grinders of the Makita brand and their features

Based on the diameter of the working wheel, the brand's grinding devices are divided into classes:

Lightweight - have a circle with a diameter of 115–125 mm. They are distinguished by easy handling.
Medium - the diameter of the circle is 150–180 mm. There are professional and household models, distinguished by motor power.
Heavy - disc diameter 230 mm. This class is represented by models for professional purposes when working with concrete, brick, etc. They are characterized by the latest protective systems.

Amateur devices vary in power and price. Professional equipment is designed for long-term heavy loads and has an increased power reserve. Models with power above 1000 W are equipped with a comfortable rear handle, which is covered with special pads to protect against vibration.

As for the design of the grinders of this brand, it is characterized by the presence of such additions:

labyrinth device, which serves to protect from dirt and dust;
armored coating of motor windings;
special system for soft start and overload protection (Super-Joint-System).

Malfunctions when working with Makita angle grinders can be divided into two types:

electrical (breakdown of the rotor, stator or defects in the control circuit);
mechanical (breakage of the bearing on the gear wheel).

First you need to inspect the device. The mechanism of operation of the grinder consists in supplying torque from the rotor by means of a gear to the spindle of the working body (circle, cutting stone).

Sources of damage can be increased loads, untimely replacement of brushes, lubricants. Thanks to the presence of a quick-detachable protective casing, Makita models are repaired in a short period of time.

There are components in the control circuit that you can repair yourself. The weak point is the brushes. Therefore, their verification is necessary first of all. And also you should check the continuity of the power supply circuits from the plug to the terminals of the switch.

If the malfunction lies in the breakdown of the switch, then it must be replaced. If the supply wire is damaged and cut, the damaged parts are removed or the entire wire is replaced.

The appearance of an unpleasant odor, constant overheating and spontaneous acceleration of the speed indicate a breakdown of the stator. The stator may have a broken winding or a short circuit. Using a tester or an IK-2 device, you can find a short circuit. In the event of a malfunction, wind up a new wire.

Failure of the stator can be the cause of the breakdown of the angle grinder. This can be understood by the large number of sparks in the collector area and the smell of combustion. The rotor is connected to the gearbox. Therefore, when removing it, it is required to disconnect it from the gearbox. Rotor repair is a complex technology. It will be more practical to replace it with a new part.

The new rotor is placed in the housing already fitted with bearings. And the drive gear is also put on. Then you should check the bearing fit and tighten the nut.

Then the rotor with the gearbox is placed in the stator. In this case, the bearing should be covered with a boot and rotate easily.

If the gearbox is damaged, play in the spindle shaft appears. The gearbox starts to wedge and the gear slips. Gearbox repair is usually associated with damaged gear teeth. For each Makita model, driven gears are attached either to the shaft or pressed onto the spindle.In addition to the driven gear, the gearbox consists of a housing and a driving gear. To repair the angle grinder, you need to replace the gears, and you should replace them in pairs. You will need a puller to remove the driven gear. You can also use a press. It is not recommended to use a hammer due to the fragility of the housing shell.

After troubleshooting the Makita grinder, components are purchased and repairs are made. The following recommendations should be adhered to:

it is necessary to start assembly by checking the parts for integrity and cleanliness;
assembly begins with sliding the bearing onto the spindle;
a driven gear is installed after the bearing;
the spindle is placed in the gearbox housing using a rubber ring;
when assembling the gearbox, the bolts are lubricated with sealant;
when placing the lubricant in the gearbox housing, the volume of its space is taken into account (the volume of the lubricant is 1/3 of the volume of the space);
at the end of the assembly, the torsion of the gearbox is checked and the bolts for fastening are screwed;
carbon brushes are replaced after 7 thousand hours of operation or wear up to 8 mm in length.

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Makita grinders are very often undergoing a repair procedure due to the high number of counterfeit devices. A frequent problem is the breakdown of the gearbox, namely, its gears.

In addition to the popular Makita brand, other grinding devices of the brands Bosch, Sparky, Stern are known. All of them are reliable and easy to use. But cases of breakdowns are not excluded.

Bosch grinders often require bearing replacement. The mechanism of the machine is based on the torsion of the spindle shaft, which is pressed into the driven gear. And it also rests on a needle bearing. If a bearing breaks down, it is very difficult to get its cage. Moreover, the drive gear is fixed to the rotor shaft with a left-hand thread. As a result, it is fixed with a nut. The gear, which is driven, is pressed onto the spindle shaft.

Reducers of Sparki grinders are characterized by a gear pair placed in a housing. The driven gear is fixed with a press or keyed connection. The key is a small diameter ball. The drive gear is also attached to the rotor shaft with a key or a right-handed nut. The grinders of this model are also distinguished by easy extraction of the brushes without removing the handle.

When disassembling Stern grinders, the gearbox can be left out of the housing. During repairs, pay attention to the key of the small gear, which does not hold well. The lubricant must be changed in a timely manner.

You can and should try to fix any tool. The grinders do not differ much in their mechanism. The diagram is always included with the purchase of the device. Therefore, any craftsman who has the necessary tools and devices can carry out the repair of working units with his own hands.

Banned
3,067 posts

City: UKRAINE. Donetsk region. Khartsyzsky district.

The answer came from the second service center.

The complete armature kit includes a fan and one bearing on the manifold side.
The second bearing costs $ 8.
The old model of the anchor, assembled - 787 UAH. ($ 98)
New model of anchor assembly - UAH 654 ($ 82)

What is the difference between the old and the new model is not clear. The partisans are silent.

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      - Members
        
        108 posts
        
        City: Kirovograd
        
        Name: Nikolay Makhotka
        
        about the anchor, try to grind it neatly and call the tester there you will see
        
        graphite is shiny and slippery to the touch, just wipe it with a brush to keep it clean
        
        Banned
        
        3,067 posts
        
        City: UKRAINE. Donetsk region. Khartsyzsky district.
        
        hramovnik (26 November 2013 - 11:24) wrote:
        Post has been edited www: 26 November 2013 - 11:48
        
        Members
        
        108 posts
        
        City: Kirovograd
        
        Name: Nikolay Makhotka
        
        well, the brushes look slightly grayish in color and with a sheen, and the charcoal ones are just black
        
        on the markets we most often come across coal
        
        Members
        
        108 posts
        
        City: Kirovograd
        
        Name: Nikolay Makhotka
        
        Banned
        
        3,067 posts
        
        City: UKRAINE. Donetsk region. Khartsyzsky district.
        
        Nub (26 November 2013 - 11:02) wrote:
        Nub (26 November 2013 - 10:36) wrote:
        So service sites only offer carbon brushes!
        Moreover, there are coal ones with self-shutdown.
        
        Banned
        
        3,067 posts
        
        City: UKRAINE. Donetsk region. Khartsyzsky district.
        
        And on other resources, in the description of the grinder - we are talking about carbon brushes.
        
        Thanks to the new design of carbon brushes and the improved brush holder used in the Makita 9565 CV angle grinder, their resource has increased significantly. With a certain degree of wear, the brushes turn off automatically, and their replacement, if necessary, is not difficult.
        25-mm-i807.html
        
        Post has been edited www: 26 November 2013 - 11:47
        
        www (26 November 2013 - 11:14) wrote:
        
        Members
        
        108 posts
        
        City: Kirovograd
        
        Name: Nikolay Makhotka
        
        www (26 November 2013 - 11:46) wrote:
        
        Banned
        
        3,067 posts
        
        City: UKRAINE. Donetsk region. Khartsyzsky district.
        
        paul89 (26 November 2013 - 11:08) wrote:
        
        Banned
        
        3,067 posts
        
        City: UKRAINE. Donetsk region. Khartsyzsky district.
        
        paul89 (26 November 2013 - 11:08) wrote:
        I connected a light bulb to the terminals of the brushes. The brushes are removed.
        The light is on brightly.
        When turned on, a characteristic sound is emitted - as if by a magnet that attracts. I did not understand the source of the sound, but it seems that springs are emitting, which press on the brushes.
        
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        It's hard to tell, but it looks like the light comes on a little slower than usual.
        
        I turned the wheel of revolutions - a grinder with adjustable revolutions, but this did not affect the burning of the light bulb - the amount of light did not change.
        
        It's not clear - is that how it should be?
        
        I think everything should be fine with a soft start.
        
        Banned
        
        3,067 posts
        
        City: UKRAINE. Donetsk region. Khartsyzsky district.
        
        I took it to the workshop, checked, - there is no interturn short circuit on the rotor.
        This makes me happy.
        
        Let's try to sharpen the collector.
        I don’t know, we’ll see how the turner can handle it.
        In the picture, someone can show - how the collector should be correctly cut - from where and to where?
        
        There is play in the bearings.
        But the master said that the backlash is in the normal range and these old bearings will last longer than new ones.
        But this same master also changed my brushes. And I asked him today, what kind of baida is this with the collector? To which he answered me - because of poor-quality brushes. You changed them, didn't you?
        I said nothing.
        
        This question interests me - what to do with bearings and how to determine whether they are suitable or not?
        
        Yes, the master also said that if the bearings are bad, then stripes are visible on the metal parts of the armature - the result of imbalance and bumpiness.
        I have - like an anchor - like from the factory yesterday.
        
        In general, what do you think about bearings?
        
        One more thing - when we put the lubricant into the gearbox ourselves for the first time, we overdid it and it was squeezed out through the bearing - onto the fan - into the engine.
        
        I heard somewhere that after such a story - the khan's bearing - does not keep the oil seal from dust.
        Although the question is what kind of dust is in the gearbox.
        
        Post has been edited www: 27 November 2013 - 14:27
        
        Any power tool can fail over time. This usually happens due to a violation of the rules for its operation. The Bulgarian is no exception. If you have such a nuisance, do not panic and immediately call the wizard, because in most cases you can fix the problem yourself.
        
        Figure 1. The device of the grinder.
        
        To do this, you need to know the basics of electrical engineering and understand a little about the design of grinding machines. Next, we will consider how to repair the grinder with your own hands.
        
        To understand how an angle grinder works, you first need to familiarize yourself with the principle of operation of this tool. With the help of electricity, the engine works, which, through a special gear wheel, transmits the rotational movement to the shaft. At its end, a grinding or cutting wheel is fixed.
        
        The high quality of work carried out with the grinder will depend on the number of revolutions of the cutting blade in 1 minute. With a professional power tool, this value can reach 10,000 rpm and more.
        
        First of all, if a grinder breaks down, it should be disassembled and thoroughly cleaned; in most cases, the tool starts to work.
        
        The layout of the grinder may differ slightly from different manufacturers, but the main parts are the same for all models (Fig. 1):
        
        two-piece body;
        
        electric motor of a certain power;
        
        reducer;
        
        electrical part.
        
        The body is made of impact-resistant plastic. Its main task is to hold all the components in place and transfer the forces applied by the operator to the cutting element.
        
        The electric motor drives the drive gear of the reducer, which rotates the driven gear, on the axis of which the disk is located. The reducer consists of gears through which the axis of rotation is rotated 90 °. Due to the use of gears of different diameters, the optimal speed of rotation of the cutting blade is achieved.
        
        Before you repair the grinder, you need to prepare tools and materials that may be needed during the repair work:
        
        tester;
        
        screwdriver;
        
        spanners;
        
        knife;
        
        tweezers;
        
        sandpaper;
        
        insulating tape;
        
        grease;
        
        alcohol;
        
        rags.
        
        The main principle that must be adhered to when repairing any power tool is that one should move from simple to complex, that is, the sequence of repair work must first exclude elementary malfunctions.
        
        When an angle grinder fails, the first step is to remember the circumstances under which the breakdown occurred. This will most likely help to establish the cause of the breakdown, which will allow for a successful repair of the grinder.
        
        Read also: DIY repair of large paint chips on a car
        
        The most common breakdowns of a grinder are open or short-circuited turns in the stator or armature windings.
        
        The most vulnerable point of the grinder is the electrical part, the breakdown of which occurs most often. It can burn out from excessive loading of the tool during work, from water entering the device, from power surges, etc.
        
        The mechanical part does not like abnormal operating modes, poor or untimely maintenance of bearings and gear elements of the gearbox, falling of the tool on the floor. Therefore, before you repair the grinder, you must thoroughly clean its body and trigger. If this does not help, then the grinder will have to be disassembled for further inspection and repair.
        
        Very often a situation arises when the grinder suddenly stops working. The first thing to do in this case is to disconnect the device from the power source and manually rotate the disc. If it does not turn or turns very tightly, then you need to completely disassemble the tool and inspect its mechanical part. If the disc scrolls easily, then this means that power is not supplied to the brushes of the electric motor. This may be due to a failure of the power cord or the "Start" button.
        
        The first step is to inspect the supply cable for integrity. Very often it bends at the point of its entry into the grinder's body. To eliminate such a breakdown, it is necessary to remove the cover from the handle of the device, and then ring 2 wires with a tester. If a break is found in any place, then it is better to replace the cable with a new one.
        
        It is better not to do twisting, because in the place of twisting the wire will bend again after a while.
        
        Grinder anchor device.
        
        When the handle cover is open, you can immediately see the condition of the brushes on the armature collector.If they are worn out, they should be replaced. To do this, open the 2 windows of the brush holder and, by bending the spring, replace it. New brushes should be the same as the old ones.
        
        Carbon deposits can form on the collector plates, making it difficult to apply the brushes evenly. In this case, the carbon deposits should be removed. To do this, take tweezers and wrap cotton wool around it. After that, take out the brushes, wipe them and the collector with alcohol, and then put the brushes back.
        
        If, after these operations, the grinder still does not start, this means that the cause of the malfunction lies in the start button, which should be repaired. For repair, you need to disassemble the trigger. In this case, it is recommended to mark the removed elements, which will save you from incorrect reassembly. The serviceability of the button must be checked with a tester. If it turns out that it is defective, replace it with a new one.
        
        Sometimes a situation arises when extraneous noise is heard during the operation of the grinder. To eliminate this problem, open the gearbox by unscrewing the 4 fixing screws. If the gear is worn out, replace it with a new one.