Home Cinema Repair: All about the gadgets
- 24 Nov 17:00
- Tips For Home
Table of Contents:
- Typical Home Theater Device
- Power Supply Unit Linear Power Supplies
- Linear Power Transformers
Home Cinema Power Cablesoftentimes eliminate power supplies in household appliances. This group has a lion's share of all failures, including when it comes to home cinema repair with their own hands. All we need to know is that there are two types of power supplies - pulsed and linear. Accordingly, it is accepted and the transformers to name exactly the same. The difference between them is that the linear operating at a frequency of 50 Hz with a voltage of 220 V, and for pulsed transistor( or any other key), a high frequency sequence is formed. Due to this move it is possible to significantly reduce the mass of the transformer, which has a favorable effect on demand. This information is well known to any owner of an inverter welder, where the network voltage is first straightened out and then converted to the proper way for transmission through a pulse transformer
Typical Home Theater Device A home theater device can be imagined as a complicated DVD player, supplemented by a splitter for Sounds around channels, chips of various interfaces.
That is basically this:
One single interface is usually easy to track, and it's funny to break: someone went to the cable, or pulled it out, by accident or specially. In this case, home theater repair is more about restoring the mechanical part, the chips often do not suffer from brutal influence. Skilled hands the problem is solved. Often, somewhere in the scheme there is no food, it can be both general supply of energy, and local problems. In the latter case, it's easier to find a place than to determine the reason. On YouTube, a video is transmitted, where overheating of one of the diodes lost its sound. Through this element, the chip of the amplifier was fed, and the microcracker with increasing temperature increased in size, due to which the electrical contact was interrupted. When using a freezer to a diode, the home theater performance was restored.(See also: Home Cinema Setup)
Floating faults to track the hardest of all. So it is a well-known case when there was a pause during the video viewing on the screen, after which the play was restored. As a result, it turned out that the fault is a floating breakdown. One of the buttons had a breakdown of isolation, and the resistance constantly rolled on the contacts, which caused the inadequate behavior of the home theater. The fact is that the keys are often connected in series, as a result, it is difficult to say which one is rejected, even if it became clear that the problem is precisely at this place. The case is complicated by the fact that the buttons are extremely difficult to spill, without damaging it. Sometimes the conducting layer burns out. In this context, a more appropriate hair dryer than a soldering iron. The micropunctions are checked in the usual way, in the open state the resistance must be at least 20 MΩ.
So before you go into the depths of your home theater, make sure that the panel is in service. If some function does not work, duplicate it from the control panel, this will help avoid unnecessary blurriness. But in general, if the brewing of home cinema repairs, then you can not do without the knowledge of the device power supply.
Pulse and Linear Power Supply
Home Theater Linear Power Supplies Despite the word order in the header, we will start considering applications in home theaters from line-based power supplies that are excellent power and are the companions of all cheap DVD players. The first question - what can break? The answer is simple! What's inside:
Often a low-power low-voltage resistor or even a trivial dart is often used instead of a fuse in modern equipment. When repairing Sony's home cinema, note the following information:
- The fuse has very low impedance, so if event X occurs, the current begins to grow rapidly, and while the thread in the glass flasks, the equipment is already seriously damaged. The resistor immediately limits the current to its nominal value, which serves as the protection of the rest of the circuit. No serious research has come into the eye, but by all indications such a scheme for a home theater should be more appropriate than the usual fuse.
You can also find elements such as varistors and thermistors in the power supply. Both the first and the second are also intended for protection( not the fact that they will work).For example, varistors often lock the short-circuited fuse. All that is said is to make only one thing: the
- The fuse can be replaced by a resistor of the appropriate denomination with the required scatter power. How to find them? Read what exactly is written on the fuse. There is voltage and current, therefore, power is easily determined. The resistor must blow out at the same parameters. The power on the case does not always mean the maximum permissible( this is the power of dispersion, in which the element is not yet lit).In this light, in order not to sit in the puddle, it will be useful to find a more complete specification on the resistor.
What else would I like to say? The fuse fails for just two reasons:
From this point of view, there is a useful method for pulse power supplies: you need to replace the fuse with a bulb instead of a fuse. If the light is on when the equipment is turned on, it is necessary to pull out the plug faster and look for damage further. But this is only true for home power cord power units. In multivers, for example, often a low-resistor resistor or a fuse is in the heating circuit, which has nothing to do with the rest of the electronics. It is clear that if this element burns, we have only two variants:
The latter is unlikely, but everything happens. How to look for a breakdown on the power supply board? Start with capacitors, none of them should be called in any direction. If you find an inflated barrel, to fix a home theater and at all will become a simple task. Find a new capacitor and capacitive voltage, and then replace it. If visual control shows that everything is in order, a home theater with a high degree of probability is ready to work. Before turning on, you should diodes from the bridge, each one must give a short circuit in one direction. Then comes the turn of the key transistor or relay.(See also: Repairing the air humidifier with your own hands)
Transformers of linear power supplies
I would like to add that in linear toroidal transformers, sometimes a thermocouple is placed between turns. In this case, the flask often indicates the trigger value and the word Fuse. Emergency situation causes a break in the primary winding. This is easily verified by the tester, do not forget that in many cases the in-line resistor of the input filter is in parallel, so the transformer needs to be screwed out of the circuit for verification. However, the first sign of the cliff is a great resistance from the plug. If there is more than 100 ohms, then the probability of 90% is precisely in the breakage of the primary winding. By the way, the heat sink burns out, as well as the usual one, including at jumps in voltage, so we should not think that this breakdown occurred precisely because the jump of voltage burned the wire.
It is not necessary to immediately throw out a transformer, it should be felt under the bellows of thickening, here and there is hidden what we are looking for. We open the lintel, under a layer of turns we find a thermoswitch, after which we replace it with a piece of wire or a purchasing element with similar characteristics( we will remind you that they are inscribed on the braid).If this is the only fault detected, repairing the home theater with your own hands will allow the equipment to function for some time.
Home Cinema Power Modules
The switching power supply is different from the linear one by the fact that the transformer is loaded with high-frequency current. This allows you to significantly reduce the size and weight at sufficiently high power. The inverter generates pulses of wavelengths at frequencies of tens of kHz, and in the home theater there is something like that. However, there are no variations, because there is no need to change the power. In this case, the frequency of passage of pulses is constant. The generator on the chip controls the base of the transistor, which, in turn, works on the primary winding. It is in this case that inside varistors and other interesting components can be found. For example, thermistors with increasing temperature increase their resistance, which reduces the current and protects other elements from failure.
Very commonly in home cinema power supply units, key circuit elements fail.