Quick speaker repair at home. Loudspeaker repair: a detailed review. Disassembling the speaker to replace parts

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How to disassemble a loudspeaker head?

Be careful not to bring steel instruments close to the magnet system, especially on the side of the diffuser or centering washer! This can damage the diffuser or the dust cap!

If you do need to use tools near the magnetic gap, use non-magnetic tools.

If the centering washer is glued with epoxy, repairing the loudspeaker without spare parts can be very problematic.

In other cases, the complexity of the repair depends only on the design of the speaker and the adhesives used during assembly. If the glue with which the suspension is glued and the centering washer can be dissolved with acetone, then you can safely begin disassembly.

Most adhesives dissolve better when the speaker is still young. It happened that such speakers could be disassembled in a matter of minutes. Glue joints made with BF-2, BF-4 glue or glue with similar properties lend themselves best to dismantling.

To disassemble the speaker, you will need the following tools and materials.

1. Acetone is a solvent.
2. Alcohol is a solvent.
3. Pipette * - for dispensing the solvent.
4. Scalpel - for cutting adhesive joints.
5. Trowel - for cutting adhesive joints.
6. Matches are used as spacers.
7. Calico (cotton fabric) - to remove glue residues.
8. Box spanner - for dismantling the magnetic system.

Other tools and materials may also be needed.

Chemically pure acetone ** is preferable to other solvents due to its relatively low toxicity. Therefore, it is better to choose acetone even when it is inferior to other solvents. For example, adhesive joints made using 88H glue dissolve better with ethyl acetate, but it is much more toxic.

True, if the diffuser and the centering washer are glued with BF-2 or BF-4 glue, then ethyl alcohol can be used as a solvent. However, the likelihood that water may be in the alcohol makes acetone the preferred choice.

Depending on what exactly is being dismantled, the appropriate dismantling techniques are also selected. So, for example, if a paper suspension is peeled off, then the dissolution of the glue should be carried out with the utmost care. If the rubber suspension is peeled off from the speaker housing, then the work can be done more aggressively.

* A convenient pipette can be made of a glass reeder and an "artificial vein" from a dropper (a rubber band into which needles are inserted right when the medicine is injected into the vein). An ordinary medical pipette quickly breaks down under the action of acetone, and its length does not allow reaching some adhesive joints.

** Pure acetone can be easily distinguished by its smell. You just need to know this smell. Unfortunately, nowadays, under the name "Acetone" they sell anything. Often some arbitrary solvent or a mixture of different solvents is poured into the bottles. And this is not surprising, because we have 400 gr. acetone costs the same as a bottle of vodka. This is a good reason to trade a bottle of vodka for a bottle of pure acetone in some industry.

Dismantling the suspension.

If you are having difficulty with perseverance, then turn on your favorite movie as the background, since dismantling the moving system of a large speaker can take a long time.

Dismantling of the rubber suspension begins from some edge where the glue beads are less. By adding acetone and raising the edge of the suspension, a cavity is created into which acetone is again poured.

The work will go faster if you start to dissolve the glue in several places at once.

Each time, adding a few drops of acetone to the resulting cavities, the edges are gradually raised. To prevent the suspension from sticking back, matches are substituted under it. As the glue dissolves, the matches are shifted to the edges of the cavity.

Dismantling a cardboard hanger from the side of the case differs from dismantling non-paper hangers only in that it requires more accuracy and patience.

No great effort should be made to avoid damaging the suspension, which becomes especially vulnerable when exposed to a solvent.

If you use too much solvent, you can damage the mounting plane of the suspension, and the corrugation itself. Therefore, if the adhesive connection is difficult to dissolve, then mechanical action must be used. A not very sharp scalpel will do here.

If you notice that the cardboard corrugation has begun to delaminate, then it is better to suspend work and think about another technology.

After dismantling the paper hanger, the mounting plane may be deformed. You can return it to its original shape if you place the diffuser on a flat glass or other solvent-resistant surface, and again slightly soften the mounting plane with acetone. During this operation, you can also remove the remaining adhesive.

In some cases, for example, when the very edge of the paper corrugation from the side of the body is already damaged, you can cut off the hanger along the edge and build up the lost fastening edge using cloth or paper. It may seem that this is a too time-consuming repair option, but if the suspension is destroyed under the influence of a solvent, it will be completely impossible to restore the speaker without having a spare diffuser.

In other cases, it is easier to peel off the suspension from the side of the diffuser, rather than from the side of the body. This method gave good results when repairing speakers 10GDSH-1 (10GD-36) with foam rubber suspensions, however, while they were new.

In some cases, when rewinding the speaker, the centering washer is peeled off only from the side of the case. This is usually done when the glue with which the washer is glued to the diffuser does not dissolve well and the diffuser may be damaged during dismantling.

But, it happens, and vice versa, that it is much easier to glue the joint between the centering washer and the diffuser than along its outer perimeter. Then it becomes possible not to center the speaker during assembly.

However, sometimes, after rewinding and assembling such a speaker, it may require additional centering. This applies mainly to speakers where the centering washer is not glued to the cone, but to the sleeve, and may be due to too large a gap between the sleeve and the centering washer.

When dismantling the centering washer from the side of the body, the adhesive joint is soaked with a solvent immediately along the entire perimeter. As the glue softens, the edge of the washer rises and matches are placed under it.

When dismantling the centering washer from the side of the diffuser, the adhesive is impregnated with a solvent, too, along the entire perimeter.

To prevent damage to the diffuser due to prolonged exposure to the solvent, the process can be accelerated with a small paddle.

At the end of the dismantling of the diffuser and the centering washer, glue residues are removed from all surfaces using a solvent and coarse calico (cotton fabric).

To prevent debris from getting into the magnetic gap, the gap is sealed with electrical tape.

Breakdown of computer speakers is a very common occurrence. Some users simply solve this problem by replacing them with working columns, but this method is not always the only correct one. Fortunately, there are many effective speaker repair methods that every home craftsman can reproduce.

The main purpose of the speakers is to amplify the weak audio signal coming from the computer sound card. By their design, any computer speakers are a stereo audio amplifier. By design, all electronic stuffing can be conditionally divided into 3 main units: a power supply unit, a stereo UMZCH (audio frequency power amplifier) ​​and a passive acoustic system in the form of 2 speakers. The speakers are usually powered either from a 220V network or from a USB port via a 5 volt line. The audio input of the speakers is connected to a computer sound card via a stereo cable with a 3.5 mm stereo plug at the end.

Basic breakdowns that can be eliminated by hand

Firstly, it is necessary to make an initial diagnosis. Try to connect the speakers to a 220V power supply. If we are talking about additional speakers from a laptop, then it is necessary to connect the power supply via USB. The illuminated LED indicating the operation may indirectly indicate the operability of the power supply circuits of the UMZCH.

Second, try touching the end of the 3.5mm stereo plug with your most common diagnostic tool, your finger. In working speakers, such a touch should cause a serious hum of 50 Hz pickup. The hum should be pronounced. If there is no such background, then this indicates either a violation of the integrity of the audio wire, or a breakdown of the 3.5 mm plug, or the failure of the UMZCH. Moreover, UMZCH - an audio frequency power amplifier fails extremely rarely, first of all, check the wires and plug.

What to do if one of the speakers doesn't work

It happens that one of the speakers works quite well, while the second one completely refuses to reproduce any sounds. Basically, this breakdown consists in breaking the contact in the plug and socket of the sound card. The problem is solved very simply: we wipe the plug with technical alcohol. The problem can be radically solved by replacing the plug.

How to check if the speakers in your speakers are working

The rarest breakdown in computer speakers is speaker failure. Practice shows that it is more likely that the cable will fray or break the contact in the plug than the speaker will break. If your suspicions still fall on the speaker, then it will not be difficult to check its performance. The simplest method is to measure the resistance of the winding under direct current. It is most reasonable to use either a digital multimeter or an analog tester for such diagnostics. We set the device to the measurement limit of 200 ohms. When connecting a multimeter to a working speaker, a reading should be displayed that does not exceed 16 ohms. As a rule, the resistance value is written on the dynamics itself. Standard values: 4.8.16 ohms. Any significant deviation from the nominal impedance indicates speaker breakage. This "sore" is treated by the replacement method. Fortunately, the cost of a speaker in a computer speaker rarely exceeds 100 rubles. If you don't have a multimeter, you can check the suspicious speaker by connecting a 1.5V battery. In a working speaker, when such a battery is connected, the diaphragm should move forward with a characteristic click and rustle.

How to replace the wire and plug

Let's make a reservation right away that you need to buy a plug and a wire for stereo audio systems, that is, the sound should be divided into 2 channels. In order for us to fully enjoy surround sound, the sound is fed to the input of the amplifier not through 2 wires, but through four wires. The plug is also made using a stereo technique. When choosing a plug, ask the seller for one where there are 3 outputs: 1 - common wire, 2 - first phase (right channel), 3 - second phase (left channel). A mono 3.5 mm plug will not work for our purposes, since there are only 2 contacts: 1 - common wire, 2 - phase (mono signal). The wire must be either three or four conductors. In a four-wire arrangement, we have two separate common lines and 2 separate phases, and in a three-wire arrangement, we have 1 common ground and 2 separate phases. The two-wire circuit is unusable for our purposes. All wires are soldered to the plug. No twists work reliably here.

The stages of termination and soldering of the cable to the plug are shown in the photographs.

How to eliminate rustling in speakers when adjusting volume

In budget models of speakers for computers and laptops, adjustable potentiometers are used. In fact, these are resistors in which there is a resistance adjustment. A special slider, moving along the conductive part of such a potentiometer, physically changes the value of its electrical resistance. In new speakers, of course, this change occurs very smoothly and quietly, but over time the grease dries up, therefore, rustling and microscopic sparking occurs, which is amplified through the UMZCH to the speakers. The problem is solved either by lubricating the potentiometer or by replacing it.

How to lubricate a potentiometer (volume control)

First you need to disassemble the column where the potentiometer is installed - the volume control. Then we solder the potentiometer and disassemble it. The complexity of soldering and the non-triviality of disassembly and assembly directly depend on the manufacturer and brand of speakers. After disassembling the column, you must do the following:

1. Remove old grease from the track.

2. We clean the entire working surface of the potentiometer from various dirt and dust. It is most preferable to use a school eraser for these purposes, but only on the side intended to remove inscriptions and traces not from pencils, but from ballpoint pens.

3. Lubricate all places where friction occurs with CIATIM grease (technical vaseline).

We assemble the potentiometer and solder it into place.

Once cleaned, lubricated and properly installed, the potentiometer will function like new, and your speakers will not emit the slightest rattle or noise when the volume level is changed.

Acoustic systems are divided into active, passive, the difference is limited by the presence of sound processing chips inside, powered by electric current. Amplifiers, filters, interfaces for reading flash media, decoding compressed audio formats. In the latter case, the speaker system approximates the functionality of the player. Consider what to do when the speakers are not working. The speakers include a myriad of sound reproducing devices, readers are interested in how they repair speakers with their own hands. You will need special glue. In the days of the USSR, BF 4, AK 20. Solvents are selected accordingly (based on glue). It will be necessary, disassembling, dismantling the connection, and repairing the speaker system yourself.

The device of a typical speaker acoustics

A movable part with a rigid plate creates air vibrations that are perceived by the human ear.

Speaker classification

Do-it-yourself repair of acoustic systems, doubting how the device works, is supposed to use the principle - do not harm. Regardless of the size, the speaker of the speaker system is formed by electrical, mechanical parts. The first is formed mainly by inductors. The second includes a permanent magnet, a membrane. Here is an incomplete classification of speakers of acoustic systems.

• Electrodynamic playback devices form three classes, the concepts of the presence of a magnet, a moving membrane, are combined:

1. Reel-to-reel are built according to the principle known to the owners (repairers) of gas water heaters. When the inductor voltage is applied, the magnetic ring makes the diaphragm move, according to the law of the applied audio frequency current.
2. In tape, the role of a variable magnet is played by a narrow corrugation. No coil, of course, inside. Matching transformers are required for speaker applications. A tag that identifies the type of speaker of a speaker system.
3. Isodynamic loudspeakers include a square, circular spiral that moves parallel to the membrane in the field of a permanent magnet.

• Electrostatic playback devices have no moving parts. The membrane vibrates without making any translational movements. The speakers perfectly reproduce high frequencies due to their low inertia.

• Piezoceramic speakers exploit the effect of converting electricity into vibrations of a quartz crystal. It is clear that you cannot achieve a high power of the device, the speaker is suitable for the purposes of reproducing high frequencies of acoustic systems. The main advantage of the technical solution is low energy consumption.
• Ionic dynamics are practically rare, the theory was developed in the 50s. The principle of operation is based on the modulation of gas ions by sound vibrations. You need to get an electric arc. Ideas are expressed for using a flame formed by positive, negative particles (air ions).

Readers are familiar with naturally occurring audio reproducing devices. There is not always a coil in the speaker system. Therefore, before the repair, in the process, the master performs the correct classification of the devices, properly carrying out the necessary operations.

Speaker arrangement of the speaker system

Partially touched the device. Let's consider in more detail the electrodynamic models. The diffuser forms the support for the cap. It is represented by the semblance of a wide horn on which the coil is glued from the back side. Flexible copper conductors that carry an electric current, punching the diffuser from the inside, fit directly to the membrane cap. The soldering points are visible from the front of the speaker. The coil is light; it is required to provide a relatively low inertia of the system. Even the tuning fork A of the first octave lies at 440 Hz. It is clear that for fluctuations of the indicated speed, the moving part of the speaker of the acoustics must be light.

The magnet is fixed on the bed. Usually circular. An inductor runs in both directions in the hole, moving the cap-membrane assembly. The connecting wires make constant vibrations. A centering washer is used to position the movable part along the vertical, horizontal axis. Perforated piece of elastic material, centering the location of the cap, diffuser. The centering washer does not interfere with the displacement of the moving part along the axis of symmetry. The repair is ridiculously simple:

Since the membrane and cap do not break, it is a matter of checking the electrical installation, the soldering points of the wires, the integrity of the coil.

Inductance is wound in the image and likeness of the old one. Each layer of turns is coated with BF 4 glue. Poor soldering is performed anew. Select the appropriate inductance winding technique. Usually a special device is made, formed by two pairs of racks, standing opposite each other on a long board. Both are connected by axles. One contains the core of the new coil, the other contains the purchased wire. It is recommended to buy the wire with varnish insulation. It is necessary to maintain the correct thickness. You can measure using a vernier caliper.

Winding is relatively fast while the glue dries. The coils fit tightly to one another, adhering to the shuttle principle. It is important to maintain the correct number of turns, properly position the terminals.

It is often necessary to disassemble a speaker of a speaker system for repair. Stock up on solvent. The glued joints are wetted, waiting for a fixed time. Please note: the joints are carefully cleaned. It is made regardless of the glue used to assemble the speaker of the speaker system.

Speaker Speaker Range

Speakers are different types of speaker systems, each with a limited frequency response. Everyone works as a kind of mechanical filter. However, it happens that you need to shift the range ... You can raise the resonance frequencies of the electrodynamic system by varnishing the centering washer. Used 5-10% solution of ZAPON, cellulose in acetone. The varnish is applied with a soft brush in a circle. Avoid misaligning the moving part of the loudspeaker. Consecutively performing the operations, we will increase the resonance frequency by 1.5–2 times, approximately one octave.

To lower the range, weights should be glued to the moving part. The correct ring of cardboard is attached to the back of the diffuser. It is necessary to more precisely maintain the symmetry of the arrangement of the parts. The sound pressure drops rapidly. The volume decreases, the range is narrowed from the high frequency side. However, in the area of ​​resonance, the loudspeaker will perform well.

You can expand the range in both directions (if there is no cap). In the center, from the front, a truncated cone is glued above the inductance coil of the speaker of the speaker system. The mass is made as small as possible. Thin, thick paper impregnated with ZAPON varnish will do. The top plate is equal to the coil, the height is half the cone, the taper is 70 degrees. Due to the increase in the mass of the moving part, the resonant frequency decreases, but the upper edge of the range rises, thanks to the rigid core, which is harder than the diffuser. As a result, the spectrum of the reproduced sounds expands in both directions. The total increase will be one and a half or two octaves, the game is worth the candle. Take care to correctly configure the electronic part: if there are passive filters on capacitors and resistors, they will limit (cut off) the capabilities of the mechanics.

Craftsmen increase the sound pressure at the resonant frequency for an unshielded magnetic system. Try to find one or a similar set ring. Then glue the second magnet on the reverse side of the one standing, the interaction of the fields will increase, therefore, the strength of the sound will increase.

The speaker system is simple and can break, they said. We hope the renovation goes off without a hitch.

DIY woofer repair

Today, the number of good sound lovers who just throw out a wheezing speaker is not decreasing! At the same time, the cost of an analogue can be a tangible amount.
I think that the following will help anyone who has a great desire and perseverance to fix the speaker, rather than buying a new woofer.

Available - a miracle of design thought, once the former column S-30 (10AC-222).

The organ clearly needed to be operated - when gently pressing the diffuser, an extraneous sound was heard (very similar to a quiet click). It was decided to trepan this organ.

First, the patient's flexible lead wires were sealed off (from the side of the contact pads).

Then a solvent (646 or any other capable of dissolving glue, such as "Moment"), using a syringe with a needle, was moistened with the gluing of the dust cap and the diffuser (along the perimeter).

Place where the centering washer is glued to the diffuser (perimeter) ...

And the place of gluing the diffuser itself to the basket of the diffuser-holder (again around the perimeter).

In this state, the speaker was left for 15 minutes with periodic repetition of the previous three points (as the solvent was absorbed / evaporated)

Attention! When working with a solvent, you should observe safety measures - avoid contact with skin (work with rubber gloves!) And mucous membranes! Do not eat or smoke! Work in a well ventilated area!

When wetting, use a small amount of solvent, avoiding getting it on the gluing area of ​​the coil and the centering washer!

Depending on the type of solvent and air temperature, after 10-15 minutes of the above operations, using a sharp object, you can gently pry off the dust cap and remove it. The cap should either come off very easily or offer very little resistance. If you need to make significant effort, repeat the operations with wetting its edges with a solvent and waiting!

After peeling off the cap, carefully pour out the remaining solvent from the recess near the coil mandrel (by turning the patient over).

By this time, the centering washer has time to peel off. Carefully, without using any efforts, we separate it from the basket of the diffuser holder. if necessary, re-wet the gluing site with a solvent.

Wet the place where the diffuser is glued to the diffuser holder. We are waiting ... We wet again and wait again ... After 10 minutes you can try to peel off the diffuser. Ideally, it should detach from the diffuser holder (together with the coil and centering washer) without effort. But sometimes he needs a little help (the main thing is accuracy! You cannot damage the rubber suspension !!!)

We clean the gluing points from the old glue and dry the disassembled speaker.

We examine the disassembled patient for a malfunction. We look at the coil. If there are no scuffs and loose turns on it, we leave it alone. When peeling off the coil, glue it back with a thin layer of BF-2 glue.

We carefully inspect the place where the lead wires are attached to the diffuser. So it is - the patient has the most common malfunction in old speakers with a large diffuser travel. The lead wire at the attachment point is frayed / broken. What kind of contact can we talk about when everything hangs on a thread passed into the center of the wiring!

Gently bend back the copper "antennae".

And we solder the lead wires.
We repeat the operation for the second wiring (even if he is still alive - the disease is easier to prevent!)

We cut the supply wiring at the break point.

And we serve the resulting ends (of course - first we use rosin). Here you need to be careful! Use a small amount of low-melting solder - the solder is absorbed into the wire like a sponge!

Gently solder the wiring into place, bend the copper "antennae" and glue (Moment, BF-2) the place where the wiring adheres to the diffuser. Remember - you cannot solder the wires to the fastening "antennae"! Otherwise, how can the wiring be changed again in ten years? ;),

We collect the speaker. We put the diffuser with all the "household" in the diffuser holder, orienting the wiring to the places of their attachment. Then we check the correctness of the polarity - when connecting a 1.5V AA battery to the terminals, when connecting the "+" battery to the "+" speaker - the diffuser will "jump" out of the basket. We put the diffuser so that its "+" lead wiring is at the "+" mark on the speaker basket.

We solder the lead wires to the contact pads. Please note that the length of the wires has decreased by almost half a centimeter. Therefore, we solder them not as it was at the factory - to the hole in the plate, but with a minimum margin to keep the length.

We center the diffuser in its basket using film (or thick paper), which we place in the gap between the core and the coil. The main rule is to place the centering evenly around the perimeter, to maintain the same gap. The amount (or thickness) of the centering should be such that when the diffuser is slightly protruding outward, it freely rests on it and does not fall inward. For the 25GDN-1-4 speaker, 4 pieces of film are enough for this, placed in pairs in front of each other. The length of the film should be such that it does not interfere if you put the speaker on the diffuser. For what - read below.

We glue the diffuser. We use the indication for the glue used (I recommend "Moment", the main selection criterion, so that the glue can be subsequently dissolved with a solvent). I usually stick out the diffuser 1-1.5 cm up so that the centering washer does not touch the basket of the diffuser holder, then I apply a thin layer of glue on it and the basket with a brush, wait and firmly push the diffuser inside, additionally press the washer against the basket around the perimeter with my fingers ... Then I glue the diffuser (in the retracted state, without skewing).

We leave the speaker upside down for several hours under load (this is why our photographic film should not protrude beyond the plane of the diffuser!)

Then we check the speaker for correct assembly. We take out the centering and carefully check the diffuser travel with our fingers. It should walk easily, without emitting overtones (there should be no touching of the coil and core!). We connect the speaker to the amplifier and send low-frequency tones of low volume to it. Extraneous sounds should be absent. In case of improper gluing (misalignment, etc.), the speaker must be glued (see above) and reassembled, being careful! With a high-quality assembly, we get 99% of a fully working speaker.

We glue the edge of the dust cap with glue, wait and carefully glue it to the diffuser. Here you need accuracy and precision - a crookedly glued cap does not affect the sound quality, but it spoils the speaker's appearance very much. when gluing, do not press on the center of the cap !!! It can bend from this and you will have to peel it off, straighten it, coat it from the inside with a thin layer of epoxy for strength and stick it back.

We wait until all parts are completely glued together (about a day) and put the finished speaker in its place. We enjoy the sound, which is no worse than that of the new factory analogous speaker.

That's it, now you can see that fixing a speaker is an easy task. The main thing is slowness and accuracy! So in an hour, you can slowly repair almost any woofer or midrange speaker of domestic or imported production (for gluing imported speakers, a more powerful solvent is often required, for example, acetone or toluene, carefully - they are poisonous !!!) having a similar defect.

After the operation, the speaker seemed to have a second wind, and he continued to stand and play in the subwoofer.

Have your favorite speakers started wheezing? Do not rush to write them off, with such symptoms it is very easy to repair the speakers with your own hands. Usually the speaker begins to wheeze due to the numerous dust that has accumulated over the years of trouble-free operation between the core and the coil, which, when the speaker cone vibrates, generates an unpleasant sound in the form of speaker snoring. In this case, repairing the speakers, you must start with disassembling and removing dust or small debris that causes a wheezing sound.

Speaker structure and design

To repair speakers, it is important to understand how a typical representative from the world of audio technology works, we will disassemble its device and design, for this, refer to the figure below.

The speaker consists of a magnetic system located on the back. It consists of a ring magnet made of special ferromagnetic alloys or magnetic ceramics, steel flanges and a cylinder (Kern). There is a gap between the core and the flange, in which the magnetic field is generated. In the gap, there is an inductance coil wound with a thin copper wire on a rigid cylindrical frame. It is also sometimes called a voice coil. The coil frame is fastened to the diffuser - it then "moves" the air, creating compression and discharge - acoustic waves.

The diffuser can be made from a variety of materials, but it is usually made from compressed paper pulp. To prevent the coil from touching the core walls, it must be placed in the middle of the magnetic gap using a centering washer. The diffuser is mounted on a metal frame. Its edges are corrugated to allow free vibrations.

Thin wires from the coil go to the outside of the diffuser and are attached with special rivets, and a stranded copper wire is attached to them on the other side. Then these stranded conductors go to the petals, so the speaker is connected to the circuit.

Now you can start DIY speaker repair.

Speaker designation on the diagram

If an alternating electric current is passed through the voice coil, it will arise, which will interact with the constant magnetic field of the speaker system. This forces the coil to either be pulled into the gap or pushed out of it at a different time, depending on the direction of the currents. The mechanical vibrations of the coil are transmitted to the diffuser, which oscillates in time with the frequency of the alternating current, generating acoustic vibrations.

The speaker in the diagrams is indicated as follows. Next to the designation there are letters B or BA and the serial number of the speaker in the diagram.

On the example of the Focal Polyglass 165 VRS model, because these speakers have high sound quality and, accordingly, are very expensive, I decided to try to repair them. On both speakers, upon visual inspection, I noticed a wire break, and it was impossible to solder without disassembly.

The diffuser in this speaker was woven from fabric. Rubber suspension. It took about an hour to disassemble the head. I used a solvent to separate the suspension. The main problem was that the main frame of the head was made of plastic, which was "dissolved" by the solvent.

Separated the centering washer with a mounting knife, there was access to the - the coil. It is usually screwed onto a metal sleeve with a very high accuracy tolerance. The sleeve itself is interesting with holes for cooling. The cap is made of plastic. All that remains is to solder the new flexible wires to the coil.

The assembly process must be carried out in the reverse order, then what was peeled off with such difficulty must be glued back, I used super glue for this, as it dries quickly. If you use long-drying glue, you will have to clamp it under a press and make special templates. An hour later I turned on the speakers, the sound was just magical.

Speaker repair was successful

I doubt that this miracle device has great practical value, but anyone can assemble it for fun in about thirty minutes. Although perhaps you had an unsuccessful repair and something is better than nothing.

The simplest electrostatic speaker is designed like this: the film is parallel to a flat metal plate with openings for free air passage. Clearance ( d) between the surface and the film, they try to make as little as possible, but at the same time nothing should interfere with the vibrations of the film.

If a voltage U n with a nominal value of about hundreds of volts (polarizing) is applied between the plate and the film with oscillations of the sound frequency U superimposed on it, then an electric field is formed in the air gap, causing some attraction of the plate and the film, thereby creating sound.

DIY electrostatic speaker design. The dimensions of the plates are 160 by 180 mm, each has many holes with a diameter of 2 mm. The plates should be slightly concave on the foil side, otherwise spacers will be required.

The design of the loudspeaker radiator is shown in the figure above. Plates 1 are located with foil to each other, between them there is a sheet of plastic film 2 (with metallization on the right), and the whole system is connected by screws 3 at the corners with a thickness of about 35 microns. It is necessary to find insulating washers under the screws, and from the foil of the plates it is necessary to draw conclusions 4, for the conclusions of the speaker, or it will be necessary to make projections on the plates and the wires are soldered directly to the foil on the projections.

If the used plates do not have natural concavity, a thin cardboard gasket 5 should be installed around the perimeter on the side of the film where there is no metallization.

To reduce the effect of "acoustic short circuit", it is advisable to install the loudspeaker in some kind of case; for this, the polished side wall of the case of a very old CRT TV is perfect.

For homemade tests, a self-assembled one was used.

Better acoustic results can be obtained with a differential design of electrostatic loudspeakers, in which the film does not experience a constant gravitational force due to the polarizing voltage, and vibrates much more easily, encountering only some air resistance. However, this will require two antiphase sound voltages of the same amplitude, obtained from a transformer with a symmetrical secondary winding. You will also need a two-layer film with a metallization in the middle.

Some theory for speaker repair

The theory behind our simplest speaker, a loudspeaker, is extremely simple: the applied voltage U generates a field of tension E = U / d... On charge q there is a force in this field F = qE... And the sound pressure created by the loudspeaker at the membrane itself: p = F / S, where S- membrane area. Divide by area and get p = qE / S... The magnitude o = q / S is called the surface charge density (we assume that the charge is uniformly distributed over the surface of the film-membrane). Then p = aE... Surface charge density is directly related to field strength: e0E = a, where e0 = 8.85 * 10-12 F / m- electrical constant. Finally, we have: p = e0E2. The expression on the right corresponds to the doubled volumetric energy density of the electric field, and the sound pressure is proportional to it!

That is why it is necessary to try to increase the field strength (voltage between the film and the plate) and reduce the gap d between them. The limit is imposed by the dielectric strength of the air - too high a field strength causes a quiet or even corona discharge.

The sound pressure is proportional to the square of the field strength, and therefore to the applied voltage U. It does not depend on the polarity of U, which makes it necessary to use, in addition to sound, a constant polarizing voltage. To reduce the "square-law" distortion, U is chosen much larger than U.

As a consequence of the speaker device, it is, in its direct essence, a typical converter that converts an electrical signal into sound waves. But in accordance with Faraday's law, with a light tap on the cone, a sinusoidal signal is formed at its contact. The position of the first half-cycle of the generated signal determines the polarity of the device. Thus, in accordance with the diagram below, there is a recognition of the position (positive and negative) of the half-cycle of the signal from the speaker.

The polarity of the device is determined as follows:

If the first half of the cycle of the sine wave is positive: it is amplified from the loudspeaker by the op-amp (IC1: C). This amplified signal then goes to the input of the gate (IC2: C), and its second input is connected to the output 2 of the flip-flop IC3: A. When the amplified signal is in one logic state, the output of the gate is also one, which switches the flip-flop IC3: B, and LED1 will flash once.
When the first half of the sine wave is negative, LED2 will blink once.