Two experiences in high-power speaker repair
(1) In the previous maintenance of the horn, the burnt voice coil was first smashed down with the tool, the debris in the T-shaped magnet gap was cleaned, and the good voice coil was installed according to the conventional method, positioning, wiring, and quick application. A, B glue, after drying for several hours, stick the dust cover, and then use it after drying. The horns that have been repaired in this process, especially the high-power horns used in entertainment venues, are more than half a year old. If you have less, you will get back to repair in a few dozen days. Most of them are loose voice coils, disconnected and connected, and you need to re-sound the ring to repair.
Later, when repairing a "JBL" 18-inch woofer for a user, after installing the voice coil, it was found that there was a considerable part of the aluminum skin remaining above the glue. Then, when the machine moves, use scissors to cut the aluminum skin into strips, then bend the cut strips into the direction of the paper cone, then apply a layer of A and B glue. After drying for a few hours, stick the dust cover. . The horns repaired in this way are durable, and some use even more than the newly purchased speakers.
(2) A lead of an Italian-made RCF300 8Ω/300W horn tweeter is broken from the root of the voice coil, and the broken joint is welded and used normally. However, after a few days, the fault reappeared. The removal and inspection found that the solder joint at the disconnection had melted open due to the high temperature generated during high-power playback. After several times of welding, the road was burned. If you replace a voice coil, the cost is too high (about 1,500 yuan), and it is not easy to buy, the performance of manual winding can not reach the level of the original voice coil. Finally, a 6.8Ω/10W cement resistor was connected in series on the tweeter lead to solve the problem of high temperature burn-off solder joint in use, but it has no effect on its power and sound quality.
When replacing the foam side of the speaker, when changing the foam edge, it depends on the diameter, size, width, thickness, hardness and foam density of the foam edge, because the foam edge is made of multi-layer foamed plastic (the density is very small). ) pressed at a specific temperature. Before replacement, use a medical scalpel to cut 360° along the cone of the voice coil (be careful not to scratch the spring plate and the voice coil braided lead wire), and then insert the voice coil and the center magnet column gap with polyester film or plastic film. Among them (the tighter the better, to prevent rubbing). At this time, one quarter of the winding of the voice coil should be raised above the upper magnet plate, and then the Shanghai-made Kangda AB adhesive and the good color enamel are 0:0.5: 0.25 (ie, A adhesive 1 , B adhesive 0.5, enamel 0.25), mix thoroughly and apply to the cut paper cone. After the new paper cone is glued for 15 minutes, it can be played completely. Be careful to adjust the position of the voice coil in the center of the magnet column and the spring plate. The spring plate is fully elastic and elastic, so that the voice coil is in the best position of the magnetic field, and the speaker will reproduce a beautiful sound.
Quickly repair high-powered speakers Because professional speakers are used in high-power amplifiers in the ballroom or outdoor stage to promote playback, it is extremely prone to overload and burn the voice coil. In addition, the speakers are also under the strong vibration of large volume bass. It is easy to smash the coil in the voice coil and burn it. Because of the high price of professional speakers (such as 15 inches of more than 380 yuan), compared with the purchase of new speakers, maintenance is more cost-effective. The conventional practice is to soak the paper cone with banana water (otherwise called Tianna water) to dissolve the glue and then remove the paper cone. Because the banana water is difficult to dissolve the glue that binds the speaker, sometimes it is forced to use the blade to remove. It is very easy to break the paper cone and wrinkle, and it takes time and effort to repair the quality of the repair. In the process of repairing the speaker for the ballroom, I summarized a set of quick-repairing speaker method, which is introduced to everyone.
1. Prepare a tool to make a diagonal knife, use a broken steel saw blade to grind the edge of Figure 1 on the grinding wheel, smooth the tooth on the grinding wheel, and then sharpen the knife edge on the stone. Finally, use a fine-grinding stone to make it a sharp hacksaw blade.
2. Remove the dust cover as shown in the speaker structure in Figure 2. Use a watercolor stroke on the adhesive edge of the dust cover to draw a positioning mark when restoring. Use a hacksaw to cut a small opening at the edge of the dust cover, and then rotate it. The speaker cuts the dust cover on one side, and after one rotation, the dust cover is completely cut off, and the dust cover is removed.
3. The sound-removing ring welds the two wires connected to the voice coil on the paper cone. Because the voice coil lead wire is glued to the paper cone with a special black paint, the black paint can be heated by the soldering iron while pulling the voice coil lead until the lead wire Vertical to the voice coil. Use a watercolor pen to draw a positioning mark on the voice coil and the paper cone, and then use a homemade hacksaw to make a circumferential cut at the bond between the voice coil and the paper cone and the elastic bracket. The diameter of the cut is smaller than the voice coil. The diameter needs to be 4mm larger. After the paper cone is cut, at the break of the paper cone, the elastic cutting bracket is cut in a circle according to the broken trajectory of the paper cone, so that the paper cone is separated from the elastic bracket and the voice coil, and then the voice coil can be gently lifted. The loop is taken out intact.
4. Rewind the voice coil to remember the burnt voice coil enameled wire diameter, number of turns. Find a glass bottle (φ48mm × 120mm) with a dew water to make the voice coil skeleton core. Then cut the 80mm wide paper strip with white paper, roll it on the glass bottle so that it is the same as the inner diameter of the voice coil, then slowly put the burnt voice coil on, then you can remove the burnt coil. And clean up the glue on the skeleton, be careful not to get rid of a small circle of paper cones and elastic brackets that have been dried on the voice coil after cutting. Use the same wire diameter enameled wire, re-wound on the traces of the original skeleton winding, each winding 8 to 10 turns, point 502 glue the coil to prevent looseness, after winding, turn the voice coil out of the line, use 502 glue Lead the wire, after two minutes, you can evenly apply a circle on the coil with the 1302K quick-drying insulating paint without drying. After 4 hours, apply a circle again. After the insulating paint is dried, roll it on the glass bottle. The strip of paper is pulled out and the rewinding voice coil can be taken out effortlessly.
5. The voice coil is used to flatten a small circle of paper cones attached to the voice coil with the elastic bracket and the paper cone on the speaker, align the voice coil with the mark, and slowly place the voice coil on the magnetic core of the speaker. Medium, but don't put it all down, make the joint between the voice coil and the paper cone 4mm~5mm higher. Find a piece of copper paper for advertising and cut it into 4 strips with a width of 7mm and a length of 160mm, each of which is folded 90°. Insert the four strips between the voice coil and the magnetic core to position them vertically, then slowly squeeze the voice coil down, make the voice coil and the cone mark coincide, and carefully adjust the voice coil and paper. At the joint of the basin, observe whether the elastic bracket has a concave shape. If it should be picked up, make it horizontal, and overlap with a small circle of elastic bracket stuck on the voice coil. Accurately coincide with the positioning and use the 1302K type. The insulating paint is applied around the voice coil and the paper cone. After the coating, carefully apply the elastic bracket under the paper cone. After 20 minutes, apply the insulating paint again, so that the thickness of the joint between the voice coil and the paper cone and the elastic bracket is not Less than 1mm, if less than 1mm, it can be applied several times. After the paint is dried, remove the paper strip for positioning, solder the two leads on the voice coil to the welding wire on the paper cone, and cover the lead with insulating paint.
6. After installing the dust cover and drying the insulating paint on the lead wire, align the mark on the dust cover with the mark on the paper cone, glue it with 502 glue, and then use the joint of insulating paint on the dust cover. After one coat, after drying, a speaker is repaired.
The use of insulating varnish as a bonding agent is convenient and the bonding strength is high. In addition, it is colorless and transparent, and the bonding marks are also small. Interested readers can try it!
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