You will need
- tester (multimeter);
- two lamp 60-100 W;
- - soldering iron and solder;
- - screwdriver under the cross;
Malfunction of the TV can be very different in nature. If it is when you enable the do not signs of life, first check voltage in the socket. If it is, unplug the TV from the mains, remove the back cover. Then check the power cord of the power supply and switch. In that case, if the voltage supplied to the unit power, we can assume it to malfunction.
First, carefully inspect the power supply. Pay attention to the darkened resistors and swollen capacitors. A healthy condenser the tip of the flat – if it is swollen, it can be assumed that he punched. Do not forget to inspect the opposite side of the Board. Check if there are breakdowns between tracks are properly soldered parts. Externally the power supply is OK, inspect the unit horizontal scan – it is the most loaded, malfunctions occur quite often.
In that case, if external inspection of the units of TV are not allowed to reveal the fault, to begin her search should check the supply voltage of the power supply. Most likely, you don't have a schematic of the TV, so find it on the Internet. According to the diagram to determine which connector of the power supply goes to the output stage line scan, and disable it (look for voltage 110-160). Instead, plug an ordinary incandescent bulb of about 100 watts.
If a separate connector no need to unsolder one of the elements of the output circuit of a given voltage on the power supply and to connect the lamp. When you first turn on the power supply unit is also connected via a second lamp. In that case, if it is brightly lit, the power supply has a fault. Check the chart to see which elements of the PSU may be faulty (broken) and directly passed through a current to the lamp.
The situation when the bulb lights up and then goes dark or poorly lit, speaks about the serviceability of input circuits of the power supply. The lamp at the entrance you can disable and a further test carried out without it.
Check power supply start by measuring the voltage across the load (the connected lamp). Check the chart to see what voltage should be present. It can be specified as connector of the power supply and the control points. The supply voltage can be provided at the output of the primary winding of the flyback transformer. It should be in the range of 110-150, depending on the size of the TV screen.
If the voltage is much higher, around 200 To check the elements of the primary circuit of the PSU, responsible for its formation. Pay particular attention to electrolytic capacitors. Externally serviceable, but the old capacitor may have a low capacity, which leads to the increase of the output voltage. With reduced need to check the secondary circuit power supply. Pay attention to the capacitors and diodes in circuit horizontal and vertical deflection.
In that case, if all voltages are OK, the fault should be sought in other units of the TV. First in row scanning.
Remember that in running there are high voltages hazardous for life! Do not touch the tube and its feeder circuits.
Advice 2 : How to check the voltage of the power supply
On the housing of the computer unit power supply indicate what voltage should be present on each of the outputs. Often, however, these stresses do not correspond to the nominal. To verify this, they must be measured.
When a healthy computer to measure the output voltage of the unit power supply is possible, using analog-to-digital converters built into the motherboard. Restart the machine and immediately start repeatedly pressing the "Delete" or "F2" (depending on model) until the entrance in the CMOS Setup utility. Select the menu item "PC Health Status" and you will see what voltage is present at the outputs of the unit power really is.
A motherboard does not show in CMOS Setup voltage source power standby mode. Measure it with a multimeter, to measure DC voltage limit of 20 volts, connect it between the black and purple wires. Make sure it is not much too high compared to the nominal as in working and in normal operating mode of the computer.
When malfunction of computer, lack of features CMOS Setup "PC Health Status" or doubts about the correct operation of the ADC on the motherboard to measure all voltages, use a multimeter operating in the same mode and at the same limit. The measurements were performed while the machine is running, while ensuring not to cause the probe short circuit.
To check voltage of the unit power at variable load use a special stand. Load each of the outputs of the parallel connected automotive lamps in such quantity that the total current consumed was somewhat less than nominal for a given output. Note that at voltages of 5 and 3.3 V automotive lights consume low current: measure in advance what it at these voltages on a single lamp.Disabling part of the lamps on each of the outputs, we can simulate the reduction of the load on the power supply. Spend the rest of the measurement in the same way as in other cases.
If a particular voltage is too high, immediately stop operation of the unit power supply and give it in for repair. Most likely, the voltage increased due to drying of electrolytic capacitors, but to change them, even off a high-voltage device, which is switching unit power supplymay only be a qualified technician.