Repairing a subwoofer at home. Repairing car speakers How to rewind a speaker at home

Detailed description diagnostics and repair of medium and high power speakers. The article was written for those who want to repair speakers and have winding and soldering skills.
I have been repairing speakers for 15 years and want to pass on the acquired skills and techniques to the Datagorians.
Sorry for the lack of detailed photos of the process, all the equipment and work are now a thing of the past. Has your speaker whined or stopped sounding and want to bring it back to life? First - diagnostics. We remove the speaker, disconnect the wires from the terminals, having previously marked the polarity. In the future, we adhere to this rule: everything that we disassemble, draw or photograph will help a lot.

We check the winding resistance with the device. There are three possible options here.
1) Break.
2) Nominal resistance.
3) Reduced resistance.

Now for the second check. Place the speaker on the magnet and carefully move the diffuser up and down. If you hear a rustling or creaking sound, or there is no movement, the speaker will have to be disassembled.

If there is no grinding, and the winding is broken - you need to check the conductivity of the flexible wires from the terminals to the soldering of the winding. They are made of threads intertwined with copper strands, which break down over time. They can be replaced without disassembling the speaker with M.G. wire. T.F. suitable section or braided tape to remove excess solder.
We solder the wires so that they do not stretch when the diffuser moves and do not touch it. We glue the soldering area with Moment glue.

If the speaker needs to be disassembled, disconnect the wires from the terminals, place the speaker on the magnet and use a swab soaked in acetone to soften the glue around the protective cap and remove it by prying it off with a non-sharp scalpel. Using the same method, peel off the outer edge of the diffuser and the outer edge of the centering washer. Carefully pull out the diffuser vertically upward without distortion.

I do not recommend unsticking the coil frame from the diffuser and the centering washer, so as not to disturb the alignment of the speaker.

To rewind you need to assemble a simple device, the structure of which is clear from the figure. The most difficult part is the reel mandrel. To make it you need to contact a turner. Mandrel length 100-150 mm, material – any metal.

Measure the inner diameter of the coil (x). The spool mandrel should have a diameter of x+0.5mm on one edge and x-0.5mm on the other edge.
At the larger end we drill a 3.2 mm hole and cut an M4 thread for attaching the handle.
Drilling through hole 6.5 mm for stud. The surface of the mandrel must be sanded.

Now you can start winding. We will need alcohol-based glue, for example, BF-2 or BF-6, paper from the MBM capacitor, wire and a lot of patience.

We dilute the glue with alcohol. We pierce the centering washer with a needle, thread the winding wire and solder it to the flexible wire. We fix the wire at the soldering point and at the beginning of the winding, gluing pieces of paper.
If the coil frame is made of metal, we paste it with a layer of capacitor paper without overlapping layers. We wind the wire turn to turn, gluing it before winding and over it. Remove excess glue with your finger. We try to wind it not tightly, but tightly.

On the first layer we glue the paper from the capacitor without overlapping layers and perform the same steps in reverse order. When the winding is ready and soldered to the terminals, you need to connect them to a 4-5 Volt power source with a current of 1-2 Amps for drying. The winding will heat up to 50-60 degrees, while the glue will dry and harden, the coil will expand slightly. This will help you easily remove it from the mandrel.

We check the free movement of the coil in the speaker gap and begin assembly.
We need to align the coil exactly in the center. There are 2 ways to do this.
1) Place a spacer made of photographic film or x-ray film into the gap.
2) Apply a small constant voltage of 2-3 Volts to the coil so that it is pulled inward a little.

Apply a layer of Moment glue to the outer edge of the diffuser and the outer edge of the centering washer and lower the diffuser vertically down without distortion and without radial displacement, and press it. You can turn the speaker over onto a flat table, and while the glue dries, solder the wires to the terminals.

After the glue has dried, remove the gasket and check the free movement of the coil in the speaker gap.
If everything is in order, glue the protective cap in place and enjoy the result!

Thank you for your attention!

Navigation through the FAQ.

Pages 2

How to disassemble a loudspeaker head?

Be careful not to bring it close to the magnetic system steel tools, especially from the side of the diffuser or centering washer! This may damage the diffuser or dust cap!

If you still need to use tools near a magnetic gap, use tools made of non-magnetic materials.

If the centering washer is glued with epoxy resin, then repairing a loudspeaker in the absence of 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 that glues the suspension 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. Adhesive joints made with BF-2, BF-4 glue or glue with similar properties are best able to be dismantled.

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 dosing the solvent.
4. Scalpel – for cutting adhesive joints.
5. Spatula – for cutting adhesive joints.
6. Matches - as gaskets.
7. Calico (cotton fabric) – to remove glue residues.
8. Box wrench – 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 “88N” glue are better dissolved by ethyl acetate, but it is much more toxic.

True, if the diffuser and centering washer are glued with “BF-2” or “BF-4” glue, then you can use it as a solvent ethanol. However, the possibility that there may be water in the alcohol makes acetone preferable.

Depending on what exactly is being dismantled, the appropriate dismantling techniques are selected. So, for example, if a paper hanger comes off, then the glue should be dissolved with the utmost care. If the rubber suspension comes off from the speaker body, then the work can be done more aggressively.

Dismantling the suspension.

If you're having trouble persevering, consider playing your favorite movie in the background, as dismantling the moving system of a large speaker can take a long time.

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

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

Each time, adding a few drops of acetone to the formed cavities, gradually raise the edges. To prevent the suspension from sticking back, matches are placed under it. As the glue dissolves, the matches are moved to the edges of the cavity.

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

Great efforts should not be made so as not to damage the suspension, which becomes especially vulnerable under the influence of the solvent.

If you use too much solvent, you can damage the mounting surface of the suspension, and even the corrugation itself. Therefore, if the adhesive joint is difficult to dissolve, then you need to use mechanical influences. A not very sharp scalpel will do here.

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

After dismantling the paper hanger, the mounting plane may become 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 any remaining adhesive.

In some cases, for example, when the very edge of the paper corrugation on the side of the body is already damaged, you can cut off the suspension along the edge and build up the lost fastening edge using fabric or paper. It may seem that this is a very 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 a spare cone.

In other cases, it is easier to peel off the suspension from the diffuser side rather than from the body side. This method gave good results when repairing 10GDSh-1 (10GD-36) speakers with foam surrounds, although they were still new.

In some cases, when rewinding the speaker, the centering washer is peeled off only from the side of the housing. 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 also happens, on the contrary, 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 alignment. This mainly applies to speakers in which the centering washer is glued not to the diffuser, 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 body side, the adhesive joint is soaked with solvent 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 diffuser side, the adhesive joint is also impregnated with solvent along the entire perimeter.

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

At the end of dismantling the diffuser and centering washer, remove any remaining adhesive from all surfaces using a solvent and calico (cotton fabric).

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

Today, the number of lovers of good sound who simply throw away a wheezing speaker is not decreasing! At the same time, the cost of an analogue can amount to a significant amount. I think that the following will help anyone who has hands that grow from the right place to fix the speaker.

Available - a miracle of design thought, which was once a column S-30 (10AC-222), now performing the functions of one of the autosubs. A week after the mutation, the patient began to show signs of the disease - he made extraneous sounds when practicing bass lines, and wheezed slightly. It was decided to conduct an autopsy.

After the autopsy, the diseased organ was removed from the patient's body - a woofer 25GDN-1-4 produced in 1986. The organ clearly needed surgery - when you gently pressed the diffuser, an extraneous sound was heard (very similar to a quiet click), and when ringing with various tones (produced by the nchtoner program), a clearly audible scratching-crackling sound was heard with a large stroke of the diffuser and when applying ultra-low (5-15 Hz) ) frequencies. It was decided to trepanate this organ

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

Then, with a solvent (646 or any other capable of dissolving glue, such as “Moment”), using a syringe with a needle, the place where the dust cap and diffuser were glued together (around the perimeter) was moistened...

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

And the place where the diffuser itself is glued to the diffuser holder basket (again around the perimeter)

The speaker was left in this state for about 15 minutes with periodic repetition of the previous three steps (as the solvent was absorbed/evaporated)

Attention! When working with solvent, you should observe safety precautions - avoid contact with skin (work with rubber gloves!) and mucous membranes! Don't eat or smoke! Work in a well-ventilated area!

When wetting, use a small amount of solvent, avoiding getting it on the place where the coil and centering washer are glued!

Depending on the type of solvent and air temperature, after 10-15 minutes of the above operations, using a sharp object, you can carefully pry up the dust cap and remove it. The cap should either come off very easily or offer very little resistance. If you need to apply significant force, repeat the operation by wetting its edges with 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 come off. Carefully, without any effort, separate it from the diffuser holder basket. if necessary, re-wet the gluing area with solvent.

We wet the place where the diffuser is glued to the diffuser holder. We wait... We wet it again and wait again... After 10 minutes you can try to peel off the diffuser. Ideally, it should effortlessly separate from the diffuser holder (along with the coil and centering washer). But sometimes he needs a little help (the main thing is to be careful! Do not damage the rubber suspension!!!)

We clean the gluing areas from old glue and dry the disassembled speaker. We examine the disassembled patient to find a fault. Let's look at the reel. If there are no abrasions or loose threads on it, we leave it alone. When a thread comes off, glue it back with a thin layer of BF-2 glue.

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

Carefully bend the copper “tendrils”...

And unsolder the supply wire.

We repeat the operation for the second transaction (even if he is still alive - the disease is easier to prevent!)

We cut off the supply wires at the break point...

And we tin the resulting ends (of course, we first use rosin). Care is required here! Use a small amount of low-melting solder - the solder is absorbed into the wiring like a sponge!

Carefully solder the wiring into place, bend the copper “antennae” and glue it with glue (Moment, BF-2) where the wiring connects to the diffuser. Let us remember - you cannot solder wires to the fastening “antennae”! Otherwise, how can the wiring be changed again in ten years?

Assembling the speaker. We place the diffuser with all the “equipment” in the diffuser holder, orienting the wiring to the places where they are attached. Then we check the correct 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 place the diffuser so that its “+” supply wire 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 maintain the length.

We center the diffuser in its basket using photographic 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 centering should be such that when the diffuser is slightly protruded outward, it will freely rest on it and not fall inward. For the 25GDN-1-4 speaker, 4 pieces of photographic film, placed in pairs in front of each other, are enough for this. The length of the photographic film should be such that it does not interfere if you place the speaker on the diffuser. For what - read below. Glue the diffuser. We use the indication for the glue used (I recommend “Moment”, the main selection criterion, so that the glue can later be dissolved with a solvent). I usually stick the diffuser 1-1.5 cm up so that the centering washer does not touch the diffuser holder basket, then I apply a thin layer of glue to it and the basket with a brush, wait and firmly push the diffuser inside, additionally pressing the washer to the basket around the perimeter using my fingers . Then I glue the diffuser (in the retracted state, avoiding distortion).

We leave the speaker upside down for several hours under a 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 movement of the diffuser with our fingers. It should walk easily, without making overtones (there should be no touching of the coil and the core!). We connect the speaker to the amplifier and feed it low-frequency tones at a low volume. There should be no extraneous sounds. If the gluing is incorrect (misalignment, etc.), the speaker must be unstuck (see above) and reassembled, being careful! With high-quality assembly, 99% of the time we will get a fully working speaker.

Apply glue to the edge of the dust cap, wait and carefully glue it to the diffuser. Care and precision are required here - a crookedly glued cap does not affect the sound quality, but it greatly spoils appearance dynamics. When gluing, do not press on the center of the cap!!! This may cause it to bend and you will have to peel it off, straighten it, coat the inside with a thin layer of epoxy for strength and glue it back.

We wait until all the 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 a new factory similar speaker.

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

Yes, after the operation, the former patient got his second wind and the cheerful yellow subs continue to do their hard bass work.

Speaker breakdowns and methods for eliminating them

Repair for a slipped coil turn.

Unsolder first flexible liner, then saturate the gasket and suspension (corrugation and lower centering washer made of fabric) of the diffuser along the diameter in the place where it is glued to the diffuser holder (siluminum or steel basket) with solvent 646-648 (the solvent sometimes does not soften the glue, you can try xylene, toluene, benzene),
and wait for the glue to soften (from 10 to 20 minutes), when you can easily move the glued surface with your finger on the corrugation and the centering washer from the silumin diffuser holder. Carefully (DO NOT TEAR IT OFF! EVERYTHING SHOULD PULL AWAY BY ITSELF, otherwise you just poured too little solvent or waited too long) remove the diffuser from the diffuser holder. Put the coils coil by coil in place and secure with a thin layer of BF-2 glue (it is possible, but worse, to use nitro glue) in especially powerful heads the coil is impregnated with a thin layer of epoxy glue. Reassemble in the reverse order, generously moistening all surfaces with solvent, thereby soaking the old glue again, put the diffuser in place, after centering the coil in the gap, begin gluing - pressing the fabric of the centering washer and the rubber (foam rubber - depending on the design of the head) corrugation to the silumin ( steel) surface of the diffuser holder into place. Center using rolled up film (for powerful heads, you can use rectangular pieces of thick cardboard, evenly distributed along the diameter of the gap, long enough for them to be easily removed from the gap after assembling the head), inserted into the gap of the core and voice coil (the cap for this is taken from the diffuser first carefully peel off, pouring solvent over the adhesive seam - make sure that the solvent does not get under the cap, otherwise the voice coil frame may peel off from the throat of the diffuser (This is exactly what happened to me: approx. Serzhi). When assembling, do not forget about the presence of a flexible connection to the coil, and do not glue past the coincidence of the coil terminals with the terminals on the diffuser holder. Using the same method, glue the gasket around the perimeter of the diffuser into place on top of the corrugation.

If there is a shortage of glue applied at the factory during assembly, glue STRICTLY with nitro glue such as Moment or Phoenix (those in large tubes) during assembly. This guarantees the ability to disassemble the head again for repairs, or in case of incorrect assembly (my old glue did not want to stick - I carefully dissolved and removed it and applied a thin layer of new one).
You need to pour a lot of solvent so that it stands and flows in the adhesive joints. You can slowly pour directly from the neck of the bottle (preferably, of course, from an oil can, which is made of chemical-resistant plastic). The solvent is toxic, don't poison yourself! He strongly rushes to the toilet after inhaling it - apparently his kidneys immediately remove the poison. Work in a ventilated place!
Protect the adhesive joints of the magnetic system itself and the center of the diffuser under the cap (glued voice coil frame) from solvent penetration, otherwise the head will fall apart completely. constituent elements. Apply only to the perimeter of the diffuser; carefully moisten the centering washer with a generously soaked cotton swab.

The main thing is CAREFULNESS! You can ruin everything, the paper is still there, crumple the coil frame and tear and crumple the diffuser, crumple and tear the cap.

In general, VERY GENTLE AND CAREFUL!

It is never necessary to unstick the magnetic system itself and it is unacceptable - the sensitivity (recoil) of the head may drop after gluing it again. For this reason, good results are not always achieved in repairing heads with a unglued magnetic system. You can glue a magnet to a core, but the magnetic force in the gap may decrease.

Rewinding a burnt out voice coil.

Carefully wind the burnt coil from the frame (if it doesn’t wind well, drop a drop of solvent), to facilitate winding and prevent the frame from collapsing, make a mandrel, which is discussed below. When winding, sketch where the beginning of the old coil was and how the terminals were sealed. Count the turns of the old coil. (Or look for information on speakers on this site. If it is not there yet, it will be soon :)) Select the wire exactly by diameter (you can measure it with a micrometer, and if you don’t have one, then wind 10 turns of wire on a suitable rod, measure the width of 10 turns with a caliper, and divide by 10) and carefully, turn to turn, wind it on a mandrel tightly inserted into the coil frame. The mandrel is made from slightly larger, relatively internal diameter coil frame, a piece of metal (preferably not too thick - it won’t compress) pipe with a longitudinal cut, so that when the mandrel is inserted into the frame, the pipe can be compressed, and then it will straighten out and press the frame tightly from the inside. You can make a cut in the pipe with a hacksaw. Take the pipe of such length that it is convenient to squeeze the free end when putting the frame on it. Wind the first turn according to the beginning of winding the old coil (as a rule, the first turn is located at the neck of the diffuser and is soldered directly to the contact rivet). Secure the first turn with thread, which is removed after winding. When winding, sometimes rotate the diffuser with the coil on the mandrel to prevent the frame from sticking on the mandrel. The tension during winding is not strong - otherwise you can compress the frame together with the mandrel (for this reason, it is sometimes useful to wedge a split mandrel from the inside by inserting a suitable wire into the cut or a hard object inside the pipe). When winding, you impregnate the first layer with liquid glue - an extremely thin layer. Handle the wire gently, otherwise you may tear off the varnish insulation. After winding the coil, saturate it (in a thin layer) with liquid glue BF-2 - diluted with alcohol (epoxy - diluted with nitro solvent 646-648), tin the leads with rosin and solder them to the contact rivets. When soldering, the use of acid and acid-containing fluxes is unacceptable, only rosin!

How to try to straighten a jammed cap.

Try to peel it off carefully - generously watering the gluing perimeter with nitro solvent 646-648 (or another - see above). After peeling off, lightly moisten it with water and firmly clamp it in a vice, selecting a punch and a matrix of a suitable convex shape for it. (my finger just straightened out - it was dented a little) After several days of exposure in a vice, process inner side very liquid epoxy glue, diluted with nitro solvent - a very thin layer!
Wait until it sets completely (liquefied epoxy can take more than 3 days to dry), then carefully glue it in place with “MOMENT” type nitro glue - the one that comes in large tubes.
Although in theory, such a head should of course be replaced with a new one.
When pressing the cap on the tweeter or midrange, you can try to stick tape on it and quickly pull it towards you. Must straighten up.

How to remove metal filings from a magnetic gap.

Very often, when disassembling heads, it is found in their magnetic gaps large number metal filings and pieces of magnet. They are removed by holding a piece of adhesive tape (insulating tape) folded in half in the gap, sticky layer out. Some experts recommend pouring rubber glue into the gap, and after it dries, pull it out of the gap along with the sawdust. I haven’t tried it myself, and I can say that this method is most likely not suitable for many gaps in which there are free cavities between the ring magnet and the core washer and the diffuser holder flange (almost all low-frequency and high-power broadband heads with a ferrite-barium ring magnet). For those heads in which there are no such cavities, and the gap is an even longitudinal slot in depth, this method is probably possible.

A little trick.

If the coil touches, sometimes this is due to the diffuser sagging downwards due to the old age of the head. Then you can try to change its position in the column - turn the bottom of the speaker up 180 degrees in the column panel. Then if the coil has not flown off, but is simply touching it due to the diffuser sagging over time, then the sagging may be compensated.
Sometimes a hitting coil can be cured by creating an opposite distortion of the diffuser using an insert into the diffuser holder (rag, foam rubber). Leave the head in this position for several weeks, and perhaps the misalignment after removing the insert will be compensated.
Unfortunately, these tricks rarely help, and you have to disassemble the head.

The principle of the electrodynamic GG device is shown in Fig. 1.

Fig 1. The device of the electrodynamic loudspeaker head / - diffuser holder, 2 - movable system, 3-magnetic circuit

The loudspeaker head consists of three main parts - a magnetic circuit 3, a moving system 2 and a diffuser holder 1.
The magnetic circuit of the GG can be made in two versions: shielded or unshielded, depending on the requirements for the equipment in which the GG is used. Various options shielded core, ring with cast magnets and ring with additional screen and unshielded circuits are shown in Fig. 2.

Fig 2. Design of the magnetic circuit of the loudspeaker head a - shielded circuit with a core magnet, b - unshielded circuit with a ring magnet, c - circuit with a ring magnet and an external screen, 1 - core, 2 - upper flange, 3 - permanent magnet, 4 - lower flange ( or glass), 5 - screen, 6 - tip

The magnetic circuit of the GG consists of elements of the magnetic circuit of the upper flange 2, cup 4, core 1 and permanent magnet 3 with tip 6 (Fig. 2.a) or the upper and lower flanges 2 and 4, core 1 and permanent magnet 3 (Fig. 2 , b). Sometimes it is placed in a shielding glass (Fig. 2,c). The constant magnetic flux created by the magnet using magnetic flanges and the core is directed into the air working gap, which has the form of an annular cylindrical slot between the core and the upper flange
As permanent magnets In unshielded circuits, ring ferrite-barium magnets (25BA170, 28RA180) are usually used; in shielded circuits, cast cobalt-containing (YN13DK24) or rare-earth magnets are used. For the manufacture of magnetic circuit parts, mild electrical or structural steel is usually used (Art. 10)
The efficiency of the GG as an electromechanical converter is characterized by the product of induction magnetic field in the gap on the length of the conductor (i.e., the length of the voice coil wire) The magnitude of induction and the structure of the magnetic field distribution are affected by the width and height of the working gap, the configuration of the flanges and core, as well as the volume and width of the permanent magnet.

Fig 3. Design of the moving head system
loudspeaker a - with a conical diffuser, b - with a dome diaphragm,
1 - voice coil 2 - centering washer, 3 - flexible leads, 4 -
suspension, 5 - diffuser (diaphragm), 6 - dust cap

Figure 3 shows the mobile GG system. It includes suspension 4, cone diffuser or dome diaphragm 5, centering washer 2, dust cap 6, voice coil 1, flexible leads 3.
Suspension 4 has the form of a corrugated annular shell, which has great flexibility in the axial direction, which allows the diffuser to perform axial vibrations with a large displacement amplitude. The suspension is cast together with the diaphragm from paper pulp or made from special soft materials(rubber, polyurethane foam, etc.)
The diaphragm (diffuser) 5 is an elastic shell of rotation (conical, dome or flat), which oscillates under the action of an axial mechanical force from the coil, exciting vibrations in the air environment and emitting sound. Currently, most GGs use diffusers made of natural cellulose materials with a successful combination physical and mechanical parameters. IN recent years Polymer, honeycomb, metal and composite materials are used as materials for diaphragms (diffusers).
Centering washer 2 is a corrugated membrane that ensures centering of the voice coil in the gap, prevents the occurrence of circular vibrations, allowing the diaphragm to make large displacements in the axial direction. Centering washers are usually made of cotton fabric, cambric or chiffon, impregnated with bakelite varnish.
Dust cap 6 is a dome or flat membrane that protects the gap from dust, acting as an additional stiffener on the diaphragm. It is usually made from paper pulp, fabric or metal foil.
Voice coil 1 is a cylindrical frame with an insulated conductor wound in several layers. As a rule, the number of layers of the voice coil is even, so that its leads come out in one direction. When an alternating current magnetic circuit flows through a voice coil placed in a radial cylindrical gap, a mechanical force will act on it, under the influence of which vibrations of the voice coil and the associated diaphragm occur. The coil frame is usually made of cable paper or metal foil; copper or aluminum wire in enamel insulation is used as a conductor.
Flexible leads 3 connect the voice coil conductor to the output connecting terminals GG.
The diffuser holder serves to connect the magnetic circuit, the moving GG system and provides fastening in the housing of the equipment where it is used. The diffuser holder is usually made by stamping from steel or by casting from silumin.
All elements of the moving system and magnetic circuit have a significant impact on the electroacoustic characteristics and sound quality of the GG.

Disassembling and assembling the speaker

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

	Then, with a solvent (646 or any other capable of dissolving glue, such as “Moment”), using a syringe with a needle, the place where the dust cap and diffuser were glued together (around the perimeter) was moistened...
	Place where the centering washer is glued to the diffuser (along the perimeter)...
	And the place where the diffuser itself is glued to the diffuser holder basket (again around the perimeter) The speaker was left in this state for about 15 minutes with periodic repetition of the previous three steps (as the solvent was absorbed/evaporated)
Attention! When working with solvent, you should observe safety precautions - avoid contact with skin (work with rubber gloves!) and mucous membranes! Don't eat or smoke! Work in a well-ventilated area! When wetting, use a small amount of solvent, avoiding getting it on the place where the coil and centering washer are glued!
	Depending on the type of solvent and air temperature, after 10-15 minutes of the above operations, using a sharp object, you can carefully pry up the dust cap and remove it. The cap should either come off very easily or offer very little resistance. If you need to apply significant force, repeat the operation by wetting its edges with 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 come off. Carefully, without any effort, separate it from the diffuser holder basket. if necessary, re-wet the gluing area with solvent.
	We wet the place where the diffuser is glued to the diffuser holder. We wait... We wet it again and wait again... After 10 minutes you can try to peel off the diffuser. Ideally, it should effortlessly separate from the diffuser holder (along with the coil and centering washer). But sometimes he needs a little help (the main thing is to be careful! Do not damage the rubber suspension!!!)
	We clean the gluing areas from old glue and dry the disassembled speaker.
	We examine the disassembled patient to find a fault. Let's look at the reel. If there are no abrasions or loose threads on it, we leave it alone. When a thread comes off, glue it back with a thin layer of BF-2 glue.
	We carefully inspect the place where the supply wires are attached to the diffuser. So it is - the patient has the most common malfunction found in old speakers with a large diffuser stroke. The supply wire at the attachment point is frayed/broken. What kind of contact can we talk about when everything hangs on a thread running through the center! Carefully bend the copper “tendrils”... And unsolder the supply wire. We repeat the operation for the second transaction (even if he is still alive - the disease is easier to prevent!) We cut off the supply wires at the break point...
	And we tin the resulting ends (of course, we first use rosin). Care is required here! Use a small amount of low-melting solder - the solder is absorbed into the wiring like a sponge! Carefully solder the wiring into place, bend the copper “antennae” and glue it with glue (Moment, BF-2) where the wiring connects to the diffuser. Let us remember - you cannot solder wires to the fastening “antennae”! Otherwise, how can the wiring be changed again in ten years? ;),
	Assembling the speaker. We place the diffuser with all the “equipment” in the diffuser holder, orienting the wiring to the places where they are attached. Then we check the correct 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 place the diffuser so that its “+” supply wire 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 preserve the length.
	We center the diffuser in its basket using photographic 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 centering should be such that when the diffuser is slightly protruded outward, it will freely rest on it and not fall inward. For the 25GDN-1-4 speaker, 4 pieces of photographic film, placed in pairs in front of each other, are enough for this. The length of the photographic film should be such that it does not interfere if you place the speaker on the diffuser. For what - read below.
Glue the diffuser. We use the indication for the glue used (I recommend “Moment”, the main selection criterion, so that the glue can later be dissolved with a solvent). I usually stick the diffuser 1-1.5 cm up so that the centering washer does not touch the diffuser holder basket, then I apply a thin layer of glue to it and the basket with a brush, wait and firmly push the diffuser inside, additionally pressing the washer to the basket around the perimeter using my fingers . Then I glue the diffuser (in the retracted state, avoiding distortion). We leave the speaker upside down for several hours under a 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 movement of the diffuser with our fingers. It should walk easily, without making overtones (there should be no touching of the coil and the core!). We connect the speaker to the amplifier and feed it low-frequency tones at a low volume. There should be no extraneous sounds. If the gluing is incorrect (misalignment, etc.), the speaker must be unstuck (see above) and reassembled, being careful! With high-quality assembly, 99% of the time we will get a fully working speaker.
	Apply glue to the edge of the dust cap, wait and carefully glue it to the diffuser. Care and precision are required here - a crookedly glued cap does not affect the sound quality, but it greatly spoils the appearance of the speaker. When gluing, do not press on the center of the cap!!! This may cause it to bend and you will have to peel it off, straighten it, coat the inside with a thin layer of epoxy for strength and glue it back.
	We wait until all the 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 a new factory similar speaker.

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

Yes, after the operation, the former patient got his second wind and the cheerful yellow subs continue to do their hard bass work.