Modern headphones, designed for high-quality sound reproduction, are mini acoustic device, the cost of which is sometimes comparable to the speakers. Therefore, in the case of their failure or change in sound quality, microphone failure is advisable before final disposal to try to repair them. You do not need to be an expert in acoustics or electrical engineering. It is enough to have experience with a soldering iron, multimeter and be careful when performing precise work.
Contents:
Causes of headphone malfunction
During use, the headphones, depending on their intended use, may be subjected to considerable electrical, climatic and mechanical stress:
1. electrical overloading
Many users, when purchasing headphones, are guided only by the manufacturer's reputation, not considering parameters such as power rating and maximum power, transmitter impedance.
In this case, if the output stages of the head unit (mobile equipment, car stereo, amplifier, etc.) will be designed for high impedance load, and the headphones will have low impedance transducers, a significant power overload is possible.
It is usually felt in the form of wheezing in the headphones. This rattle, even over a short period of time, can cause the headphone voice coil to burn out or mechanically detach it from the transmitter structure. This is a serious and often irreparable malfunction.
2. Moisture or rainwater entering the dynamic transducer of headphones
Headphones used for sports training, walking or travel are often exposed to extreme climatic conditions (sweat, rainwater, high or low temperatures).
This can lead to moisture entering the sound channels of the speaker system, directly onto the speakers. Over time, this can lead to loosening of the adhesive mounts and the deterioration of materials and contacts.
Some users do not follow the requirements for storing headphones. For example, when storing headphones under the windshield of a car, in summer they can get hotter than 100 degrees Celsius.
3. mechanical stresses
Most consumers have thrown their headphones onto a coffee table more than once from a height of 20-30 centimeters. In proportion to its parameters it is similar to the situation if a loudspeaker is thrown from a height of 2 meters. The second more dangerous mechanical factor is mechanical stress on the cord.
As a result of stretching, breaking, or damaging it, thin conductors can tear, disrupting the electrical connection. The most problematic places are the wire connections to the emitters, the connector, the splitter-regulator, and the Y-couplers.
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The main signs of malfunction, identifying possible defective elements
In order to determine the specific location of the fault, you need to have experience with a multimeter. A simple digital multimeter is enough to repair headphones.
Possible signs of malfunction:
1. No sound from one dynamic radiator.
The first thing to do is to check the circuit. To do this you need to use a multimeter and a headphone circuit. A typical circuit for headphones without a microphone with a three-pin connector.
In the case of coaxial conductors the circuit looks like this:
Thus, to test the left channel, you should connect the multimeter probes (in resistance measurement mode at the 200 ohm limit) to the outermost pins of the connector. To test the right channel - to the first and second pins from the connector body.
Depending on the type of dynamic emitters, the resistance may be from units to tens or hundreds of ohms. Zero resistance indicates a shorted circuit, infinite resistance indicates an open circuit or speaker malfunction. To get a more accurate indication of the cause of the problem, you should feel around the cord where it connects to the jack, radiators, splitter, and regulator.
The connection points of the wires to these elements of the headphones are most often where the wires break (breakage). If contact appears when the cord is actuated, it is likely that the speakers are in good working order. This way you can determine the exact location of the broken wiring.
2. The speakers work, but the volume is lower and the headphones sound mono.
This is caused by a break in the common wire. In this case the headphones will not ring in any of the options shown in Fig. 5. They will ring when the multimeter stylus is connected between the extreme and middle pins of the jack.
3. Both dynamic emitters are out of service.
In this case, there is usually a double fault: both transmitters not working, a break in the two conductors, or a conductor plus a non-functioning transmitter. This malfunction occurs when the headphone cord has been subjected to heavy mechanical abuse, or as a result of prolonged use with one channel not working.
4. Crackling while adjusting the volume control.
The malfunction is the result of wear and tear of the variable resistor. It should be changed. You can remove the crackling for a while by rubbing the working area of the resistor with a lead of a simple pencil.
5. The microphone does not work.
The microphone is usually connected to pin 4 of the connector.
In this case it is necessary to test 1 and 4 (outermost) pins of the jack. If the headphones use a condenser type microphone, it may not ring. An oscilloscope is required to check its functionality.
6. The sound in one of the speakers has become quieter.
The radiator sound channel may be clogged. This can be blown out with an ordinary bicycle pump (never with your own breath).
Procedure for the repair
After determining the specific location of the malfunction, the repair can proceed.
In order to carry out the repair work, you will need:
- A soldering iron with a power up to 40 watts;
- Active flux;
- Low-temperature solder PIC-60 or other;
- sharp knife, can be clerical;
- duct tape;
- heat shrink (a tube, the diameter of which decreases when heated);
- stranded copper wire in polyvinyl chloride (PVC) insulation with a cross-section up to 1 sq.mm.
If the conductors are broken, use a knife to remove the PVC insulation from the areas of the alleged breakage. Copper conductors may have additional lacquer insulation, which should also be stripped with a knife.
Similarly, strip the wire from the repair kit. Next, the solder joints should be tinned. This requires the use of flux and solder. If you don't have any active flux on hand, you can use acetylsalicylic acid (aspirin), which is available in any medicine cabinet.
The soldering process can be tricky: headphone conductors are often made of oxygen-free copper, with woven silk threads for greater resistance to mechanical stress. Some craftsmen also use aspirin to remove the lacquer insulation.
By placing the wire in the lacquer insulation on the aspirin tablet, touch the tinning area with a heated soldering iron. The corrosive environment removes the insulation. You should not breathe these fumes: the sensation is not pleasant.
Similarly, solder at breakage points near connectors, splitters, emitters. If the conductor breaks right next to the connector, you must buy a new assembly. It is available at any store that sells radio components.
Microphones and speakers are usually not repairable. They can be replaced with a functioning one from another similar earpiece. If the conductor has broken off where it connects to the speaker, an attempt can be made to disassemble the body of the transmitter. This can be done by using solvent to loosen the glue connection.
Before soldering, place a heat shrink sleeve on one of the wires. After splicing, move it to the joint, and heat it gently with an industrial hair dryer or lighter as a last resort.
General recommendations
- To ensure that your headphones last longer, do not subject them to unnecessary tests.
- Before carrying out repairs, clearly locate the fault.
- Thoroughly isolate the contacts, and test them with a multimeter after the repair. A short circuit can cause a mobile or other device to malfunction.
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