Diodes in hair dryer. Wiring diagram for a hot air soldering gun. Something is blocking the fan

Hair dryer is electrical appliance, which is a piece of pipe through which a stream of air heated to 60 ° C is supplied at a high speed in a given direction. Often, for ease of use, the pipe is equipped with a pistol grip.

The photo shows a 1600W Melissa Magic hair dryer. On the handle there is a switch for operating modes, with which you can turn on the hair dryer and stepwise change the temperature of the air emanating from its nozzle.

A building hair dryer in appearance, principle of operation, device and electrical circuit practically does not differ from a hair dryer. Only in it the air flow is heated up to 600°C.

The device and principle of operation of the hair dryer

When the hair dryer is on cold air from the room is sucked into its pipe with the help of a rotating impeller mounted on the shaft of a DC motor. Further, the air flow passes through a tetrahedral heat-resistant frame made of mica or ceramic, on which a heated nichrome spiral is wound. Cooling the spiral, the air flow is heated to a temperature of 60°C, and in the building to 600°C, after which it exits the pipe.

On the body of the hair dryer, there is usually a switch combined with a step-by-step setting of the operating mode, which allows you to turn on the hair dryer in full or half power mode.

The photo shows appearance typical sliding switch of operating modes.

To prevent skin burns during hair drying and the destruction of the hair dryer body in case of engine malfunction, a thermal protection in the form of a bimetallic plate is installed on the frame.

When the air is heated above the set temperature, the bimetallic plate bends upwards in the direction of the arrow in the drawing and opens the contacts. The heating coil is de-energized and the air heating stops. After cooling, the bimetallic plate returns to its original position, and the contacts close again.

As you can see, the principle of operation and the device of the hair dryer are not much different from other heating household electrical appliances and any home master can repair the hair dryer.

Hair dryer circuit diagram

Most building hair dryers and hair dryers have the wiring diagram below. The supply voltage is supplied through a C6 plug with a flexible cord. Capacitor C1 serves to suppress interference emitted by the brush assembly of the motor. Resistor R1 is used to discharge the capacitor C1 after disconnecting the plug from the outlet to prevent electric shock to a person when touching the pins of the plug. In some models, elements C1 and R1 are not installed.

The operation of the hair dryer is controlled using switch S1. In its position, shown in the diagram, the hair dryer is in the off state.

When the switch slider is moved one step to the right, its movable contact closes terminals 1-2 and the supply voltage through the rectifier diode VD1 is supplied through the current-limiting coil H1 to the motor and the heating coil H2. The diode cuts off half of the sinusoid and thus reduces the speed of rotation of the impeller and the heating power of the H2 coil by half.

When the engine is moved one more step, contacts 1-2-3 are closed, all mains voltage is applied to the heating element and the engine and the hair dryer operates at full power.

Usually, DC motors are installed in hair dryers, designed for a supply voltage of 9-12 V. To reduce the voltage, an H1 spiral is used. To convert AC to DC, a diode bridge VD2-VD5 is used. The electrolytic capacitor C4 smooths out the ripples. Spark quenching capacitors C2-C3 perform the task of extinguishing sparks in the brush-collector assembly of the engine and suppressing radio interference.

The S2 button is used to switch the operation of the hair dryer to the cold air blowing mode. When you press it, the H2 coil stops heating.

To protect the hair dryer from overheating, which can occur due to a decrease in the speed of the impeller in the event of an engine malfunction, there is a thermal protection element St, which opens the supply voltage circuit to the H2 heater when the maximum allowable temperature air flow.

How to repair a hair dryer with your own hands

Attention! When repairing an electric hair dryer, care must be taken. Touching bare areas of a circuit connected to electrical network can lead to injury electric shock. Don't forget to unplug your hair dryer!

If a broken hair dryer got into your repair, then first of all you need to find out how outward signs hair dryer was faulty. According to them, using the table below, you can immediately guess where to look for a malfunction.

How to disassemble a hair dryer

It can be more difficult to disassemble a hair dryer than to repair it, since parts of the body are usually connected inside using latches, the location of which is outside can not see.

But there is always a self-tapping screw on the handle in the area of ​​\u200b\u200bthe entrance to the power cord housing, usually closed with a decorative plug or sealed with a label. Thanks to different color parts of the body of the Braun hair dryer shown in the photo, you can see along which line to disassemble it.

This is what the decorative plastic plug looks like in the hair dryer case. Since it is the same color as the handle, it is difficult to notice. To remove the plug, you need a sharp object, for example, an awl or a knife with a sharp end of the blade, pry it over the edge.

After removing the plug, the head of the self-tapping screw became visible, but it turned out that the slot on it is triangular, while its edges are made in such a way that the self-tapping screw can only be screwed clockwise. The manufacturer provided that at home it was impossible to disassemble the hair dryer for repair without breaking the case.

To unscrew a screw with such a head, it was first heated using the tip of a heated electric soldering iron. To do this, just press the soldering iron tip to the head and hold for a couple of minutes. From the heating of the self-tapping screw, the plastic around the thread softened. Further, until the plastic has cooled, using a screwdriver with a flat sting width equal to the length the edges of the slot triangle of the self-tapping screw were unscrewed without difficulty.

In order to avoid difficulties in the follow-up repair of the hair dryer during assembly, the self-tapping screw was replaced with the same size, but with a slot in the head for a cross bit.

The removable part of the case was additionally held on by four more latches. Two of them were on the sides of the pipe. For disassembly, it was necessary, simultaneously with the dilution of the parts, to squeeze them out through the gap formed with a flat screwdriver.

After disengaging the side latches, the upper ones released themselves. The latches were shallow, so I was able to disassemble the hair dryer without breaking them.

In this hair dryer, the power cord was faulty, and therefore it was not necessary to disassemble it further, since the place where the cord was connected to the electrical circuit became available.

Hair dryer repair examples

Most often, hair dryers break down due to rubbing of the power cord or malfunction of the electric motor with the impeller. In modern hair dryers, due to the presence of thermal protection and the use of thick wire for winding the spiral, it very rarely burns out. Of the dozens of hair dryers repaired by me, there was no blown spiral.

Hair dryer power cord repair

When drying hair, the hair dryer moves intensively and the power cord is constantly bent. Although the wires in the cord are copper and stranded, they break off over time from repeated kinks. A sign of the beginning of a wire break is the periodic temporary cessation of the hair dryer while drying the hair.

Therefore, half of the breakdowns are associated with chafing of the power cord at the point of exit from the case, less often at the plug. The first sign of such a breakdown is interruptions in the operation of the hair dryer while drying the hair. At this stage, it is easy to find out the location of the cord defect. It is enough to fix it in the middle and move the cord first at the entrance to the plug body, and then at the entrance to the hair dryer body. If the hair dryer works stably at the same time, then the cord is in order and the fault must be sought elsewhere.

If the wires in the cord are frayed at the point of exit from the plug, then you can repair the hair dryer without disassembling it. How to replace the plug is described in the article "Electric plug, how to connect, repair".

Usually, the wires of the cord inside the hair dryer are soldered to the printed circuit board or connected using the terminals, as in the above photo.

To check the cord, you need to ring the wires by touching one of the tester or multimeter probes to one of the pins of the plug. With the second probe of the multimeter, alternately touch the ends of the wires. One of the wires should show zero resistance. There should also be zero resistance between the remaining wire and the second pin of the plug.

If the wires are ringing, then moving the cord at this time, you can determine exactly where the wire is frayed. In the repaired product, the cord was cut off at the point of entry into the hair dryer.

If the wires of the cord are soldered to the printed circuit board, then you can ring them without soldering by attaching the probes of the device to the pins of the plug. The dryer switch must be set to maximum power. The heating coil has a resistance of about 30 ohms. Therefore, if the cord wires are working, then the multimeter should show the same resistance.

By using online calculator You can accurately calculate the resistance value of the nichrome hair dryer coil, based on its maximum power.

In the hair dryer being repaired, the cord was broken at the point where it was inserted into the body. To restore work, you need to cut off the defective section of the wire and remount the cap terminals. To remove the terminals from the wires, you first need to use a knife to unbend the antennae to the sides that fix the wires, as shown in the photo.

In the next step, the frayed section of the wire is cut off and the insulation is removed from the cord and wires. The length of the cord will decrease by a dozen centimeters, which will not affect performance.

It remains to tin the wires and terminals with solder with an electric soldering iron and solder them together. After putting on the terminals, assembling and checking the operation of the hair dryer, the repair can be considered complete.

If there is no soldering iron at hand, then in this case the wires are cut off at a distance of 3-5 cm from the place of connection to the electrical circuit of the hair dryer and a segment of the defective cord is removed. Then the wires are connected with one of mechanical methods, depending on the internal free space in the handle of the hair dryer.

Engine Power Circuit Repair

I got a Melissa-1600 hair dryer to be repaired, complaining that the air flow from it had become weak with a burning smell. When checking, it turned out that the impeller rotated at insufficient speed. I immediately assumed that hair was curled on the motor shaft between the impeller and the housing. Usually, in most cases, with such signs, this happens.

But after disassembling the hair dryer, it turned out that one of the rectifier diodes installed on the motor was torn in half. The continuity of the remaining diodes showed their serviceability. Therefore, the engine worked, but only one half-wave of the rectified voltage was supplied to it.

The faulty diode was soldered and in its place, with the observance of polarity, the first type KD105 that came across was soldered. The motor supply voltage is usually 9-12 V at a current of not more than 0.5 A. Almost any rectifier diode will provide such parameters.

At the same time, winding hair was removed from the motor shaft and the bearings were lubricated with machine oil. To do this, it is enough to apply a drop of oil to the fixation point of the shaft in the motor housing and turn the shaft by the impeller several times.

Before installing the engine in a hair dryer, it is advisable to check it. For the operation of the motor, a constant voltage of 9-12 V is required. But since the voltage is supplied to the diode bridge, the motor can be powered from both a direct and alternating current source. Even the simplest adapter from any device will do, giving out the appropriate voltage and current up to 0.5 A.

You need to apply voltage to the input of the diode bridge, the points of its soldering to the electric circuit of the hair dryer. If the engine is connected to a source constant voltage, then you need to check first with one connection polarity, and then change the connected wires in places. This is necessary to test all bridge diodes.

Tests of the engine after prevention and repair showed that its impeller, when scrolling by hand, rotated easily and when voltage was applied from an external voltage source at a sufficient speed.

Checking the hair dryer after assembly showed that its performance was fully restored. The impeller rotated at high speed, and the smell of burning disappeared.

Repair of the switch and cold air switch button

If the hair dryer cannot be turned on and the power cord is working, then the cause, as a rule, is a broken contact in the mode switch. And if all the modes of the hair dryer, but the air does not heat up, then the heating off button is faulty, the heat protection or the spiral is burned out.

The mode switches in a hair dryer are usually soldered into a small printed circuit board, which is fixed in the guides or screwed with screws. The photo shows the switch leads soldered into the PCB. The hot air switch is visible on the left side.

If the mode switch does not ring, then you can try to clean the internal contacts with a thin tool through the hole located next to its engine. It happens that only the contact of one of the operating modes has burned out, and the rest are in working order. In this case, you can sacrifice the rarely used mode of operation of the hair dryer and switch the switching to a working contact.

It happens that due to burnt contacts as a result of heating, the switch housing is deformed and the engine is wedged. In the absence of a replacement switch, you can connect the wires directly, leaving only one operating mode for the hair dryer. In this case, you will have to turn on the hair dryer by connecting its plug to the outlet.

If the button to turn off the warm air flow is faulty, and there is nothing to replace it with, then it is enough to short-circuit its conclusions. In this case, this function will no longer work, but otherwise the hair dryer will work as before.

Thermal protection repair

Thermal protection consists of two contact contacts, one of which is fixed on a bimetallic plate. When the plate is heated above a given temperature, it bends upwards, as the arrow in the photograph shows. As a result, the contacts open, and the power supply circuit of the heating coil is broken.

If the button to turn off the hot air supply is in order and the spiral is intact, then it is obvious that the contacts in the thermal protection relay have oxidized. To restore, it is enough to introduce fine-grained sandpaper folded in half into the gap between the contacts and, pressing the bimetallic plate from above with your finger, stretch the paper several times.

Heating element malfunctions - coils

If the air flow from the hair dryer is cold when the engine is running, the shutdown button and thermal protection are working, then the breakdown is associated with a nichrome spiral.

A broken spiral is easy to detect by external inspection. And the violation of contact in the joints in the form of hollow rivets on the frame of the hair dryer of the ends of the nichrome wire with the wires coming from the mode switch cannot always be determined by appearance. If the rivets do not have blackening, then in this case only a continuity test with a multimeter will help.

To restore contact in the rivet joint, it is necessary to additionally compress it with the help of pliers. The work must be done carefully so as not to break the fragile mica or ceramic frame.

Burnout or breakage of the spiral in modern hair dryers practically does not occur, but if such a failure occurs, then the spiral will need to be replaced with a new one. Splicing helix wire by twisting or crimping into a piece of aluminum or brass tube will not lead to long-term success. If the spiral is worn out, then after such a repair it will soon burn out in another place.

A nichrome spiral, taking into account the power of the hair dryer, can be purchased new or wound independently from nichrome wire, calculating its diameter and length according to the table.

Hair removal and lubrication of the hair dryer motor shaft

Another common hair dryer malfunction that can be fixed by yourself, having only a standard set of tools at hand, is when the hair dryer is working, but the outgoing air jet is very hot with a burning smell due to winding hair on the motor shaft or poor lubrication of the motor bearings.

Removing hair from the motor shaft of the BaByliss hair dryer

The BaByliss dryer shown in the photo came to me for repair with a complaint that the outgoing air stream had become weak and very hot.

When checking, by the sound of the fan, it became clear that the frequency of its revolutions was underestimated, and the cause of the malfunction lay in the operation of the engine. To fix the problem, the hair dryer had to be disassembled.

In order to disassemble the BaByliss hair dryer, you first need to remove the nozzle by unscrewing two screws. Next, using a screwdriver with a flat sting, the fixing ring is removed, installed on the side of the heated air outlet. It lends itself easily.

It remains to separate the body halves, which are held by two latches on each side. In the photo, due to the translucency of the plastic, the latches are clearly visible, as in the photo in the form of light stripes.

The hair dryer is disassembled and it remains to get to the place of the shaft where the hair is wound. The engine is fixed inside a plastic housing, which is a pipe in such a way that to remove it, you need to remove the fan impeller. And the impeller, as a rule, is tightly mounted on the shaft, and here usually great difficulties arise, since it is impossible to grab the impeller with a standard tool, and it is easy to break it.

To solve such problems, I have made a special tool from Chinese platypuses - a platypus with the ends of the sponges bent at right angles. With the help of a vice, the ends were easily bent, as they were not hardened.

With this platypus, I also successfully repair the runners of snakes and lightning, in case the links stop closing. Ordinary pliers often cannot be reached. And thanks to the curved ends of the jaws, in any case it is easy to squeeze the part of the slider that closes the links.

In addition to the upgraded platypus pliers, it is convenient to hold axles and shafts, nuts and other items different forms- do not slip out, as from pliers with flat jaws.

After removing the impeller from the motor shaft, access to the twisted hair appeared. In this model of a hair dryer, a brass bushing is mounted on the motor shaft, and an impeller is already put on it. Usually it is mounted directly on the motor shaft.

It remains only with a sharp object, such as a knife, awl or needle, to remove the hair and collect the hair dryer in reverse order. In order to avoid difficulties when assembling the hair dryer, I advise you to take a few photos when disassembling.

Hair removal and lubrication of the motor shaft of the Viconte hair dryer

The Viconte hair dryer had the same outward manifestation of the malfunction as the BaByliss, but in addition the air came out with a burning smell and the fan worked with a rattle. This indicated that the lubrication of the engine bearings had developed.

The sequence and technology of disassembling the hair dryer is similar to that of the BaByliss hair dryer, so there is no need to describe it.

The supply voltage with the help of two wires was applied to the diode bridge soldered at the motor terminals. For ease of repair, the wires were soldered with a soldering iron. You don't have to remember the colors of the wires, since the bridge is supplied with alternating voltage, and the order of connecting the wires does not matter.

An attempt to remove the impeller from the motor shaft with the help of the platypuses described above was not successful, even with the application of great muscle strength. I had to figure out how to remove the hair and lubricate the bearing without removing the impeller.

The idea came up that you can not suffer with the removal of the impeller, but drill a hole in the engine holder housing, which was done.

The location of the hole to be drilled must be measured so as not to get into the motor housing or the impeller base. First, a hole was drilled with a diameter of three millimeters, and then reamed to five. The body plastic is soft and thin, so the hole can be made with the end of a pointed knife.

A hook was made from a paper clip to remove hair from the motor shaft. To make such a tool, you need to bend the end of the paper clip, sharpen it on sandpaper and bend the very tip to a length of two millimeters. In a minute, all the hairs were removed.

To lubricate the bearing, I had to use a medical syringe. It is enough to apply one drop of oil to the entry point of the shaft into the engine. In order for the oil to get into the bearing, you need to hold the impeller and move the shaft several times along the axis, scrolling it.

Lubricate the bearing on the opposite side of the shaft. Any machine oil is suitable for lubrication, for example, for pouring into a car engine. If there is no oil at hand, then you can remove the oil level dipstick from the engine, from which you can take a few dripping drops.

To test the operation of the fan, a voltage of 10 V was applied to the diode bridge from a DC power supply. The engine will work at a voltage of 5 to 12 V, so even a charger from any phone will do. It is not necessary to do such a check, but if possible, it is better to make sure that the fan has worked as expected.

Check showed normal work engine, without extraneous noise and sufficient air flow pressure. The hole made can not be closed, as it fits snugly against the body of the hair dryer. If not, then you can stick it with tape.

As you can see, it is not at all difficult to eliminate the most common hair dryer breakdowns, and such work is within the power of anyone if desired. home master. In any case, it is worth trying to repair a failed hair dryer before buying a new hair dryer.

We are all familiar with such an auxiliary tool in construction as a construction electric hair dryer, which we are used to using to remove paint and varnish coatings.

The fundamental principle of the construction hair dryer is not much different from an ordinary hair dryer that we use to dry our hair.

Accordingly and circuit diagram building hair dryer is similar to the electrical circuit of an ordinary hair dryer.

The topic will be explained:

• electrical diagram of a building hair dryer;
• the principle of operation of the building hair dryer;
• possible causes of failure;
• troubleshooting these problems.

Wiring diagram of a building hair dryer

Consider the electrical circuit \Fig.1\ building hair dryer:

One diagonal of the diode bridge is connected to an external source of alternating voltage 220V.

The other diagonal of the diode bridge is connected to the electric motor.

The electrical circuit consists of the following elements:

• toggle switch that implements the temperature control mode - K1;
• toggle switch, which performs the speed of rotation of the rotor of the electric motor \ blowing speed control \ - K2;
• toggle switch for turning off heating elements - K3;
• electric motor\fan\ - M;
• capacitor - C;
• TENOV - R \ TEN \;
• diodes - VD1, VD2.

Through the diode bridge circuit \\ one diagonal of the bridge\, the rectified current of two potentials\+, -\ is supplied to the electric motor. During the transition from the anode to the cathode, the current flows at a positive half-cycle of a sinusoidal voltage.

Two capacitors connected in parallel in the electrical circuit serve as additional smoothing filters.

The blowing speed occurs due to the variability of the resistance in electrical circuit, that is, when switching the speed toggle switch to highest value resistance, - the speed of rotation of the rotor of the electric motor decreases \due to the voltage drop\.

The number of heating elements \ heaters \ in this scheme is four. The temperature regime of the building hair dryer is carried out by a temperature control toggle switch.

The heating elements in the electrical circuit have different resistances - accordingly, the heating temperature when switching from one section of the electrical circuit to another - the heating of the heating elements will correspond to its resistance value.

The general appearance of a building hair dryer with its names of individual parts is shown in Fig. 2

The following electrical circuit of the building hair dryer \ Fig. 3 \, is comparable with the electrical circuit of Fig. 1

There is no diode bridge in this electrical circuit. Blowing speed control and temperature control - occurs when switching from one section of the electrical circuit to another, namely:

• when switching to a section of an electrical circuit - consisting of a diode;
• when switching to a section of an electrical circuit that does not have a diode.

When current flows in the anode-cathode junction of the VD1 diode, which has its own resistance, the heating element2 will heat up according to two resistance values:

• resistance at the transition anode - cathode of the diode VD1;
• resistance of heating element \TEH2\.

When current flows in the anode-cathode junction of the VD2 diode, the voltage supplied to the electric motor and heating element1 will take on the smallest value.

Accordingly, the speed of rotation of the rotor of the electric motor and the heating temperature of the heating element for a given section of the electrical circuit will correspond to the direct transition of the current of the diode VD2. The heating of the heating element \TEN1\ for this section also depends on its internal resistance, that is, the resistance of the heating element is taken into account.

Building hair dryer malfunctions

The main reasons for the failure of a building hair dryer here can be called a malfunction of electronic elements:

1. diodes;
2. capacitors.

Most often, such a malfunction occurs with a sharp jump in an external AC voltage source. For example, the cause of a capacitor malfunction is caused by the fact that the capacitor plates are short-circuited during a power surge.

Of course, such a possibility of a malfunction as a break in the stator winding of the electric motor / winding burnout / is not excluded.

Minor faults can include reasons such as:

• oxidation of the contacts of the temperature control toggle switch;
• oxidation of the contacts of the blower speed control toggle switch;
• oxidation of the contacts of the toggle switch for turning off heating elements;
• wire break in the network cable;
• malfunction plug\lack of contact\.

Diagnostics to identify the cause of the malfunction is carried out by the "Multimeter" device.

When replacing a capacitor, its capacitance and nominal voltage value are taken into account.

When replacing a diode, the resistance of two values ​​\u200b\u200bis taken into account, in the directions:

• from anode to cathode;
• from cathode to anode.

As we know, the resistance value from the anode to the cathode will be much less than from the cathode to the anode.

With an electric motor, if it malfunctions, things are more complicated. With such a malfunction, it is easier to replace the electric motor than let's rewind the stator windings. But even such work is feasible - who is directly involved in such repairs. In this case, the following is taken into account:

1. the number of turns in the stator winding;
2. section of copper wire.

Such a malfunction as a burnout of the heating element is not excluded. The replacement of the heating element is carried out taking into account its resistance value.

Diagnostics and repair-building hair dryer

Let's consider the device of electric motors and how exactly it is necessary to carry out diagnostics electrical machines, as they are usually considered in the section on electrical engineering.

For good example, photographs of several types of such electrical machines are presented - related to collector electric motors. The device and the principle of operation are allowed for two collector electric motors:

• vacuum cleaner;
• building hair dryer

— is no different. The difference in electric motors is only in the speed of rotation of the rotor and in the power of the electric motor. Therefore, we, as it were, will not focus our attention in the sense that explanations are given that are not related to the electric motor of a building hair dryer.

Electric motor of the building hair dryer

The electric motor of the building hair dryer is asynchronous, collector, single-phase alternating current.

asynchronous collector electric motor of single-phase alternating current

The electrical circuit of the collector motor \Fig.5\ is as follows:

In the circuit, we can notice that the collector motor can operate both from AC and DC - these are the laws of physics.

The two stator windings of the electric motor are connected in series. Two graphite brushes in contact - in electrical connection with motor rotor collector.

The electrical circuit is closed on the rotor windings, respectively, the rotor windings in the electrical circuit are connected in parallel through a brush-collector sliding contact.

diagnostics of motor stator windings

The photograph shows one of the methods for diagnosing the stator windings of an electric motor. In this way, the integrity or breakdown of the insulation of the stator windings is checked. That is, one probe of the device is connected to any of the output ends of the stator windings, the other probe of the device is connected to the stator core.

In the event that the insulation of the stator winding is broken and the wiring of the winding closes to the core, the device will indicate the mode short circuit\zero resistance value\. From this it follows that the stator winding is faulty.

The device in the photograph indicates one when diagnosing - this will not yet mean that this stator winding is serviceable.

It is also necessary to measure the resistance of the windings themselves. Diagnostics is carried out in the same similar way - the probes of the device are connected to the output ends of the wires of the stator windings. With the integrity of the windings, the display of the device will indicate the value of the resistance that one or another winding has. If one or another stator winding breaks, the device will show “one”. If the wires of the stator winding are short-circuited to each other as a result of overheating of the electric motor or for other other reasons, the device will indicate the lowest \ zero \ resistance value or “short circuit mode”.

How to check the rotor winding for resistance with a device? - To do this, you need to connect two probes of the device with two opposite sides collector, that is, you need to make the same connection that graphite brushes have in electrical connection with the collector. The diagnostic results are reduced to the same indications as when diagnosing the stator windings.

collector plate wear

What is a collector anyway? - The collector is a hollow cylinder consisting of small copper plates of a special alloy, isolated both from each other and from the rotor shaft.

In the event that the damage to the collector plates is insignificant, the collector plates are cleaned with a fine-grained sandpaper. Again, this amount of work can be performed directly only by specialists involved in the repair of electric motors.

The electrical circuit \Fig.7\ consists of a battery and a light bulb, this scheme comparable to the scheme of a flashlight. One end of the wire with a negative potential is connected to the stator core, the other end of the wire with a positive potential is connected to one of the output ends of the stator windings. If the wires are connected the other way around, that is, “plus” to the stator core, “minus” to the output end of the stator winding, nothing changes from this.

If there is an insulation breakdown, when the stator winding is closed with the core, the light bulb in this electrical circuit will light up. Accordingly, if the light does not burn, then the stator winding is not closed with the stator core.

This way of diagnosing \Fig.7\ is not complete. Accurate diagnostics is carried out only with an Ohmmeter or a Multimeter with a set resistance measurement range, for subsequent measurement of the resistance of the stator windings.

Almost every home has a small appliance called a hair dryer. A hair dryer can be used when tarring wooden skis, removing old paint, blowing sawdust off a workbench, dispersing mosquitoes and husbands, drying things, cooling a pan with dumplings and as a fan on hot days. Hairdryer is also applicable when drying hair.

Most hair dryers of Chinese origin have a primitive electrical circuit. In such hair dryers, there is only one switch, which turns on the fan and the electric heater (heater). Heating elements can be made in various modifications, but in all hair dryers they are made of nichrome, twisted into a spring. More advanced hair dryers have two regulators: one controls the blowing speed, and the second controls the temperature of the blown air. At the same time, the scheme does not become smarter.

So, a hair dryer came to hand Chinese made. The fault was the inability of the hair dryer to change the blowing speed. There was no upper airflow limit.

As is often the case in Chinese manufactory, self-tapping screws have a very strange head. A special screwdriver is also needed for such a head. You can buy such screwdrivers, but it’s bad luck to unscrew Chinese screws with Chinese screwdrivers. Therefore, using an ordinary grinder from a screwdriver, you can make a tricky screwdriver under the head with the necessary self-tapping screw.

Self-tapping screws can be for a plus screwdriver, a flat screwdriver, an asterisk, a hexagon, a triangle, a square and a plug. In my case it was a fork.

On the handle there are control switches for regulating the functions of the hair dryer.

The hair dryer is powered by 220 V, 50 Hz. There is a paper capacitor at the input to eliminate interference from the engine. The hair dryer has two controls. One regulator turns on the engine and powerful heating element-4, and the second - auxiliary heating elements-1, heating elements-2. Without turning on the blower, none of the heating elements will start working. When the blower is turned on at the first speed, the voltage is initially supplied to the VD1 diode, rated for a current of at least 1 A. After the diode, the wires branch out to the heater-3, which limits the voltage to the DC motor connected through the VD2-VD5 diode bridge and to the second blower temperature controller , connected through an opening temperature contact located inside the circuit with heating elements.

The voltage after the diode VD1 from 220 V becomes approximately 155 V, and the heating element-3 limits the voltage to the diode bridge to approximately 16 V. Capacitor C1 equalizes the pulsating voltage after the diode bridge VD2-VD5. At the second blowing speed, the VD1 diode is excluded from the circuit and a voltage of 220 V drops on the heater-3, limited to about 27 V.

At the first blowing speed with the heating elements turned on, the consumption is 0.9 A, but already at the second speed the current increases significantly to 6.8 A. The current corresponds to a load of about 1.5 kW. The electrical circuit of the hair dryer is shown below.

After unscrewing the two screws, you can remove upper part hair dryer body. If you can't take it off, keep it. plastic parts. Sometimes additional screws are hidden by stickers.

Switches, a set of heating elements wound on one frame and covered with a cover are hidden in the case. The cover is needed to create an air channel in which air will circulate. If the cover is removed, then the heater, in addition to air, will heat and melt the body of the hair dryer, so when repairing, you should not heavily load the hair dryer without a cover. The cover is made of paper impregnated with a non-flammable base and painted with heat-reflecting paint.

In this hair dryer there is a lotion - an ionization button, but like everything in cheap technology, this button only turns off the block of paired heating elements.

The diode bridge with the capacitor is assembled directly on the motor itself. This saved space.

In addition to cheap Chinese household hair dryers, there are hair dryers professional level. Typically, such hair dryers are made in Europe, but given that cheap labor is concentrated in Asia, there are professional hair dryers made in China.

The main feature of professional hair dryers is the presence of a motor not for 16 V with voltage reduction by means of a heating element and DC power, but for full 220 V AC. By design, such a motor belongs to single-phase AC collector motors and is supplied with brushes. The use of such an engine allows you to fully use the ionization function, which allows you to completely turn off the heating elements of the engine.

A beautiful element is a frame with wound spirals. Usually the spirals are wound from nichrome (an alloy of nickel and chromium). Nichrome has a dark gray color. The specific resistance of nichrome is on average 1.1 ohm * mm 2 / m. Nichrome wire length L, m is calculated by the formula

L \u003d U 2 * P * d 2 / 4 * P * p

Where U is the supply voltage, V;

P is the number of pi, P=3.14;

d is the wire diameter, mm;

P is the power given off by the spiral, W;

p- resistivity wire, ohm * mm 2 / m, p \u003d 1.1.

If it is necessary to wind a spiral for a hair dryer with a power of 1200 W, rated for a voltage of 220 V, the existing nichrome wire has a diameter of 0.3 mm, then substituting the values ​​into the formula, we have

L=220 2 *3.14*0.3 2 /4*1200*1.1=2.6 m

To reduce the length occupied, the wire is twisted into a spiral, winding it around the rod.

Modern heating elements have a silver metallic color and are wound not from nichrome. Nichrome soft material, and the metal in the heating elements is solid and holds its shape perfectly. I don’t know what exact metal is used in modern heating elements.

Faults:

Hairdryer construction (technical) - a hand-held power tool for the directed supply of heated air for the purpose of non-contact (indirect) heating of the material being processed. The scope of the tool is very extensive: from simple drying with air at room temperature, to powerful exposure to temperatures above five hundred degrees Celsius. The demand for building hair dryers is fueled by their low price (for entry-level models), due to the simplicity of the design and, in many respects, time-tested circuit solutions.

Interskol FE-2000 is a representative of household building hair dryers with a minimum necessary set functions: smooth temperature control, two modes of airflow intensity. This set, as a rule, is quite enough to perform the vast majority of tasks. A specific instance of this hair dryer (the first modification, the DB3011 board) was purchased about three years ago, had a rather considerable (but not prohibitive) daily operational load. For this reason, all the imperfections in the design of the hair dryer appeared quickly.

A few months after the start of operation, the first breakdown occurred: there is no temperature control, the outgoing air is always cold. The cause of the breakdown is overheating of the BTA16 triac, its failure due to insufficient pressure on the radiator and non-use of heat-conducting paste. The repair consisted in replacing the triac with preliminary application of KPT-8 paste. This crash has not happened again.

Dryer Interskol FE-2000. Suitcase included.

Nozzle. Weeden ceramic heater with a spiral inside.

At the end of the first year of operation of the hair dryer, there was a fracture (internal rupture of wires) of the power cable next to the body of the tool. This malfunction is often found among non-professional tools. original power cable high quality does not differ, it has insulation of medium hardness, the fourth-fifth class of flexibility of copper current-carrying conductors. Installation of a new cable KG 2x1.5 (in rubber, double insulation) made it possible to forget about this type malfunctions.

In the second year of operation, the high-resistance winding of the heater, which serves as a power supply ballast for the electric motor, broke. It is difficult to establish the cause of the breakage, it can be either a factory defect (which is most likely), or spontaneous grinding of the nichrome wire on the hard edges of ceramics, due to many heating-cooling cycles. The winding broke - the engine stopped. As a result of the engine shutdown followed by overheating of the main (high-temperature) winding of the heating element, the thermal fuse tripped (the high-temperature winding remained intact). The body of the hair dryer was disassembled, the heating element was disassembled, the place where the nichrome wire broke was located. The place of the break turned out to be near one of the ends of the winding, for this reason it was decided not to connect the ends of the wire, but to wind (remove) a short section. The resistance of the ballast winding was reduced, according to approximate calculations, by 8-12%, which is not critical for the engine. By this time, extraneous noises from the engine bearings began to appear occasionally, and its time, unfortunately, was clearly coming to an end. The standard thermal fuse had a nominal trip temperature of 125°C, it was replaced with a new one with more high temperature 150°C. A small temperature margin is explained by the assumption that an additional 25 ° C is unlikely to allow the heating element winding to burn out (in the event of an emergency), but it will give more time to promptly turn off the hair dryer before the thermal fuse trips (breaks). To replace the thermal fuse, you need to almost completely disassemble the heating element. About half of all ceramic rings, from which the core of the heating element is drawn, cracked over time (apparently due to Low quality ceramics) and, when the outer shell of mica is removed, the rings break up into small particles. The thermal fuse is connected to the winding of the heating element and to the power wire using miniature crimping sleeves, which must be crimped again with high quality (without special tool) is very problematic. For the convenience of a possible replacement of the thermal fuse in the future, it was installed using flat connectors (car terminals).

By the end of the second year of operation, the plain bearings in the engine began to “ring” strongly. Also, randomly, the voltage on the high-temperature coil of the heating element began to disappear and reappear when the regulator knob was turned. These malfunctions quickly worsened, further normal use of the hair dryer for its intended purpose was not possible: the engine hummed, its speed dropped, it was almost impossible to set the desired heating temperature. There is an urgent need for a deep restoration of the hair dryer's performance.

The body of the hair dryer is opened (photo above). Housing fixing screws (photo below).

The insides of the hair dryer Interskol FE-2000.
From left to right: board, impeller motor, mode switch, heater.

DB3011 board.

Heating element of hair dryer Interskol FE-2000.

Replacement of the electric motor.

Finding the right engine for sale is not an easy task. Therefore, when an engine of a suitable size was found, it was decided to purchase an engine regardless of its other characteristics (speed, voltage). As a result, it turned out that the purchased motor had several times less supply voltage (12 V) and, approximately, one and a half to two times less revolutions than the regular hair dryer motor. These tasks had to be solved, but first you need to remove the old one and install a new engine in the hair dryer body. The process of replacing the engine is not very complicated. Greatest difficulty represents the dismantling of the plastic impeller from the motor shaft. With the help of improvised means, we organize a wedge-shaped stop from the bottom of the hub and, using a drill with a diameter of 2 mm, we gradually knock out the motor shaft. As the shaft exits, the position of the stop (wedge) must be corrected. Be extremely careful not to damage the plastic hub of the impeller! Before putting the removed impeller on the shaft of a new engine, it is necessary to fix the engine with two screws and degrease the surface of the shaft with acetone. It will not be superfluous to clean and degrease the inner surface of the impeller hub with gasoline or alcohol. We put the impeller on the shaft of the new engine manually (you can slightly nail it with a miniature rubber mallet), resting the other end of the shaft (located near the brush-collector assembly) into something solid.

Impeller motor.

Close-up of a plastic impeller.

We remove the impeller from the engine.
Use tweezers as a stop. On the drill, which rests on the motor shaft, we apply light blows with a small hammer.

Capacitors were not installed on the new engine.

Measurement of the native engine.

Thermal fuse (photo on the left). Connector flat type RpIm + RpIp (photo on the right).

Engine power supply.

There are two ways to solve the problem of powering an electric motor: increase the length (number of turns) of the ballast winding or supply power to the motor from some other source. The first method is complicated by the need to find the right nichrome wire and a place to place additional turns in the heating element (which literally crumbles in your hands). Let's take the second path - we will make separate source nutrition. The charger from cell phone. The charger board is placed next to the standard board of the hair dryer, it is necessary to ensure the proper levels of insulation (to prevent unwanted touches of the boards) and fastening (fixation). But there is one catch - the output voltage. As you know, for a charger it is about 5 V, and we need 12. Therefore, we will increase the number of turns in the secondary winding of the output transformer of the power supply (charger). We solder the transformer, disassemble the magnetic circuit, carefully separating the ferrite core into two halves (heating the transformer to 100 ° C and using acetone can simplify the task). In extreme cases, if it is not possible to disassemble the magnetic circuit, it can be wound according to the shuttle principle, so that the number of turns is small. The main thing is not to split the ferrite!

We find the finishing end of the secondary winding and begin to slowly wind up turn after turn, counting their number and remembering the direction of winding the wire. When the secondary winding is wound, it is necessary to make elementary calculations to determine the number of turns for the motor supply voltage (in our case, 12 V): find the number of turns per 1 V (knowing the former output voltage of the charger), multiply the target supply voltage by it . It will not be superfluous to add a couple of turns in reserve (if necessary, they can be quickly wound up).

We increased the output voltage by 2.4 times, the maximum load current naturally decreases by the same value. As you know, the current of the transformer winding depends on the cross-sectional area of ​​the conductor. To determine the minimum allowable wire cross-section for a new secondary winding, we measure the diameter (and calculate the cross-sectional area) of the wound wire, divide the resulting value by 2 (rough approximation, we will not delve into the wilds of calculations). If the width of the gap for laying the wire allows, then it is not at all necessary to choose a thinner wire, the main thing is to fit the required number of turns and freely put on the magnetic circuit. We wind the wire turn to turn, observing the direction of winding and counting the number of turns. Upon completion, we solder the ends of the wire to the transformer terminals, not forgetting to remove the insulating enamel at the soldering points. We cover the mating ends of each of the two halves of the magnetic circuit with a zaponlak, assemble the transformer by pressing the halves of the ferrite to each other for a while until the varnish dries. We tightly wrap two or three layers of a thin strip of insulating tape or paper tape on top of the magnetic circuit, cover it with zaponlak on top, and dry it. We solder the transformer into the power supply board, connect the motor, measure the voltage. If it is too large, we wind the turns. When the voltage is correct, we fix the secondary winding - we apply a thin layer of zaponlak on it. The transformer is ready. It should be noted that as a result of this alteration, we received only one engine rotation speed, namely, its certain average value in relation to the two initial (passport) speeds.

Cell phone charger board before rework.

We disassemble the transformer.
The secondary winding of the transformer had 12 turns of wire D = 0.35 mm in one layer.

Photo on the left: a coil with PETV enameled wire D = 0.32 mm, which will be used to wind the transformer.
Photo on the right: a wound coil of a transformer (29 turns of PETV D = 0.32 mm in two layers).

Circular winding with insulating tape (photo on the right).

The rewound transformer is installed on the power supply board (photo on the left).
The motor power supply board is ready for installation in a hair dryer (photo on the right).

Standard diodes (D1-D5) powering the engine are dismantled to obtain additional free space (photo on the left).
The motor power supply board is in place (photo on the right).

Replacing the variable resistor.

To make sure that it is malfunctioning, instead of the high-temperature winding of the heater, we will connect an incandescent lamp (see a similar example in the article -). We supply power to the board and see that the lamp does not adequately respond to the rotation of the variable resistor. We solder the regular variable resistor, temporarily connect any other (known to be good) with the same resistance of 100 K. We see correct work schemes: the duty cycle of the lamp flashes is clearly tied to the angle of rotation of the handle (engine) of the variable resistor, and in one extreme position of the engine there is no lamp glow, in the other - full heat is observed. The fault is localized, we change the variable resistor with a new (serviceable) one. In our case, an engine with lower speeds was installed, and the intensity of the spiral airflow decreased. It is necessary to limit the maximum heating temperature of the coil, in order to avoid its overheating and / or tripping of the thermal fuse. To do this, in series with a variable resistor (into the gap of the side output corresponding to the maximum power), we solder a constant resistor, the resistance of which is determined experimentally, visually observing the color of the heating of the spiral.

The left photo shows the old (left) and new (right) variable resistors.
The right photo shows the new dual type variable resistor (2 x 100 K). Opening the package is the fastest way to determine the pin assignments.

Needle files will help to give the desired shape to the handle of the resistor (photo on the left).
A new variable resistor is installed (photo on the right). Inside the red heat shrink tube is a 130K additional resistor.

The degree of heating of the spiral in the position of the regulator knob, corresponding to the maximum air temperature.

Measurement of minimum and maximum air temperature.

Conclusions.

The technical solutions used in the design of the Interskol FE-2000 building hair dryer of the first modification are not unique and are not highly reliable. The hair dryer is rightly not positioned by the manufacturer as a tool for professional use. The tool is quite suitable for use in everyday life. If there is some initial level of user training, it will not be great work independently restore the performance of the hair dryer, as its maintainability is good. Future owners of the FE-2000 model, and those who plan to use the hair dryer intensively, can be recommended immediately after purchase to check the quality of the thermal contact of the triac with the radiator and, if necessary, apply heat-conducting paste. Also, it will not be superfluous to immediately replace the power cable with a better one.

Once you see a professional building hair dryer in operation, and appreciate its capabilities, you also come to have such a thing at home. Take it off so gently old paint, no harm to decorative wooden and thin metal parts, as it is done with a building dryer, you will never succeed with blowtorch or gas burner.

When working with open fire, it is unrealistic to ensure the same safety decorative elements and work safety.

A building hair dryer (aka a hot air gun and a heat gun) is not at all like household appliance for styling and drying hair, which is necessary for every woman. The blown air temperature of the hot air gun reaches 650 °C. And there are even more powerful professional models that raise the air temperature up to 800 ° C. Also, for hair dryers not intended for drying hair, the blowing speed has been increased to 650 liters per minute. The power of factory assembled hot air guns ranges from 500 to 2500 watts.

Increasing demand for hot air guns is fueling price increases, especially for budget models. But you can assemble a building hair dryer yourself.

Why do you need a building hair dryer?

• Peeling off old paint.
• Removing stickers.
• Dismantling of linoleum, vinyl coverings, tiles.
• Softening and melting of wax, resins, bitumen, solder. Forming candles from wax and paraffin.
• Dismantling and installation of microcircuits and transistors.
• Crimping heat shrink insulation.
• Waxing furniture, skis, surfboards.
• Bending and shaping wooden parts. Drying glue after repairing surfboards, skis.
• Drying paint, varnish, plaster, plaster, wood.
• Soldering of thin-walled copper pipes.
• Antiseptic treatment of wood. Cleaning and disinfection of cages for birds and animals.
• Loosening rusted or heavily tightened metal bolts, nuts, screws.
• Hot fit bearings, bushings.
• Defrosting frozen car locks, water pipes and taps, refrigerator freezers.
• Compound plastic pipes and garden hoses, repair of car bumpers and other products made of plastics with a low melting point (polyvinyl chloride, polyethylene).
• Bending and molding of high melting point plastics (Plexiglas).
• Kindling coals in the grill.

The power part of a powerful hair dryer

The design of all thermal hair dryers is the same:

• heat-resistant housing of the heating element;
• heating element;
• fan;
• switching and switching circuit.

First what you need to do is find a piece of ceramic tube or mica plates to secure the heating element.

Second- wind the heating element. The heat gun circuit can have up to four separate spirals, with the help of which the selection is carried out temperature regime when switching the control switch. Each heating element in this case has a different resistance. Most often, two spirals with a resistance of 97 and 260 ohms are enough to select the temperature.

Hair dryer spirals are best wound from soft nichrome, which is easier to find. Fechral is a rarer material on sale, besides, the wire from it is more rigid.

Now, all that remains is:

1. Find a wire made of a material with high resistivity.
2. Measure the resistance of the wire at one meter.
3. Measure the length at which the resistance of the piece will be 97 ohms.
4. Twist the cut piece of wire in a spiral along the hairpin.

Adjust the fan to blow hot air. In the circuits of factory-assembled building hair dryers, a commutator motor with brushes is always installed, which can operate on both AC and DC.

To assemble a hair dryer at home, it is easier to use a fan from a computer. But the electric motor computer cooler can only work on direct voltage, so a rectifier diode bridge is required to connect it.

All factory-assembled hot air guns are assembled according to a scheme that allows you to change the blowing speed and heating temperature.

blowing speed decreases when switching the electric motor toggle switch to power through a spiral with a large resistance, on which the voltage drop is higher.

Heating temperature also decreases when a heating element with a higher resistance is connected, which consumes less current.

Judging by circuit diagram building hair dryer, the fan motor is in no case connected directly to a 220 V network, but taking into account the voltage drop across heating elements it operates on a voltage of 9-15 V.

For the rectifier bridge VD2-VD5, you can use separate diodes 1N4007 or finished assembly KTS109A.

As a valve VD1, you must use a high-voltage diode, for example 6A10.

Ceramic capacitors of constant capacity C1 - 3.3 μF, 50 V and C2 - 0.47 μF, 400 V are necessary to reduce the surge current during start-up and connection to the network.

As you can see, it’s not difficult to assemble a building hair dryer yourself.

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