It is quite understandable the horror that covers the owner of a home theater when an expensive device fails. What to do? Do-it-yourself repair of household appliances at home is a way to save money and your own time. If you have at least basic technical knowledge, then try to consistently understand the cause of the breakdown and eliminate it.
Specification of the problem
The first, and it is also the main difficulty that one has to face during the repair, is breakdown diagnostics. A home theater in the simplest approximation consists of four devices:
- signal source;
- acoustic speakers;
- receiver or amplifier.
First of all, you need to understand which of the components does not work. Let’s assume that there is a certainty that there is a normal input signal, but the screen remains dark. So the monitor is broken. If you have certain skills, then you can try to repair it yourself. If there is no sound, then the speaker system may be damaged. If there is sound, but turns off after a while, then the amplifier has broken. No disc loading — signal source is not working.
By minimizing losses to one device, you can decide on the repair.
The hand immediately reaches for the phone to call a specialist from the service center. Do not hurry! Perhaps the breakdown of the cinema can be fixed with your own hands at home, decently saving on the invitation of a professional.
First independent step
In a home theater system, there are always a bunch of connecting wires, which end with connectors (the only exception is wireless acoustics). During operation, the individual components of the cinema, of course, at least a little, but moved. If there are animals at home, and the wires are not laid in special channels, then it is easy to assume that they played with these wires. In addition, connector pins can oxidize.
The first stage of repair is a visual inspection of the connecting wires.
If they are in order (not pressed by furniture), then you need to remove each connector, clean it with alcohol or an eraser and insert it with force. We make a trial inclusion and, if the malfunction has not disappeared, we move on.
Power as the basis of device viability
Next, we check the power supply of the device, since in 90% of breakdowns the problem is precisely in power supplies. Both linear power supplies are used (they are quite easily repaired at home), and pulsed ones (repair requires certain skills).
Any type of power supply must have circuit breakers, with the verification of which any repair begins. It should be noted that many companies have moved away from the use of traditional (thread in the flask) fuses, and are replacing them with low-value resistors. They more accurately perform the protection function, due to a strictly fixed current limit. There are only two reasons for the failure of the fuses:
- ripple in the network, much higher than normal;
- breakdown (usually short circuit) in the circuit of the device itself.
A common cause of power supply failure is the failure of electrolytic capacitors.
All electrolytes should be visually inspected. If the condenser barrel is swollen, there is a liquid leak — feel free to replace it. The remaining capacitors are checked with a tester: it should not ring in any direction. If there is no confidence in the measurement, then it is necessary to unsolder one leg of the capacitor.
Next comes the check rectifier bridge diodes. Either of them should show a short in one direction only. It is also a good idea to test varistors and protection thermistors, but this is not always possible using only a tester.
On models with toroidal transformers, thermal fuse. To check it, you need to solder it from the circuit. Like a standard one, it can burn out from a sharp drop in input voltage, protecting the primary winding of the transformer. Therefore, if the transformer fails, it is not necessary to throw it away. It is better to find a tubercle under the braid, remove the thermal fuse from under it, replace it with a piece of wire for the first time. Such repairs will enable the cinema to continue to work.
Switching power supplies in home theaters it is much more complicated in its design than linear ones. Usually, key elements burn out — thyristors, powerful transistors, microcircuits. When repairing the impulse unit, a load, the so-called equivalent, is necessary. At home, it is usually not.
If the switching power supply fails, it is better to contact a specialist.
Cinema sound problems
Often complain about the loss of sound in home cinema after a short period of normal operation. For example, in Panasonic home theater systems, the f61 error is displayed. This is usually associated with failure power amplifier or bass amplifier. Their unstable operation leads to the fact that the output to the speakers is turned off.
If the power supply is OK, then the reason is usually in the preamplifier. It is worth paying attention to the diodes from which the voltage of 2.5 volts is supplied to the digital sound controller. It happens that these diodes work in the «leakage» mode: sometimes they work, sometimes they don’t. Replacing the element makes the repair a success and home cinema works again.
Sometimes the lack of sound is due to trifling reasons and it is not at all necessary to run from the workshop. One of these failures is no sound adjustment. This happens due to a defect in the operation of the positional sound switch on the front panel. It must first be soldered elementarily, eliminating bad contacts. If it doesn’t help, you need to remove it and clean it, having previously disassembled it. As you can see, everything is very easy.
Often found subwoofer failure, with the rest of the speakers fully working. The search must begin with an examination of the wire leading to the subwoofer: you need to ring it with a tester. Finding no damage, you need to check the connectors both in the subwoofer itself and in the cinema.
If this attempt fails, there are two options:
- the subwoofer itself is broken;
- cinema sound amplifier failure.
Repair of such complexity is undesirable at home, it is better to contact the workshop.
No external signal
The external signal source in a home theater is usually DVD player. When it starts to “limp”, then the picture “freezes” or the disk simply cannot be read. It is necessary to start the repair with an elementary cleaning of the lens with special wipes.
It is worth paying attention to the quality of the discs being played. If the disc «crumbles», it contaminates the heads.
If the simplest method does not help, then you need to remove the drive. Often the problem lies in his carriages, over time their mechanics wear out. Operation carriage replacement extremely simple and quite affordable at home.
The next step in the repair could be motor replacement in a DVD drive or laser head. But these operations are best done in a specialized workshop.
There are cases of failure expensive processor. This is usually due to an extremely simplified stabilization scheme in the device itself. As a result, the processor gets very hot and fails. In order to avoid this trouble, it is best to invest in a high-quality voltage stabilizer, and turn on the home theater through it. At the same time there will be protection against peak voltages. The benefit of a voltage stabilizer for a TV is also obvious: this sensitive technique suffers from voltage drops no less than a home theater.