How to check the posistor on the TV

The posistor is one of the parts of the system that is responsible for demagnetization. With high magnetization, the TV image is distorted or streaks appear. Their appearance means that the device is out of order. It is necessary to check its performance. If necessary, the repair or replacement of the posistor is carried out.

How to check the posistor on the TV

A posistor and a resistor are elements that are able to change their resistance when heated. Resistors show slight temperature increases. The posistor also blocks the incoming electrical voltage to it, so its temperature can increase significantly.

To check the posistor for operability, it is necessary to determine the characteristics that are considered standard during operation. If deviations are noticed in them, then a breakdown has occurred. The characteristics are as follows:

  1. Resistance is nominal. This condition works only at normal room temperature (not lower than 18 and not higher than 27 degrees).
  2. Resistance is determined by the point that characterizes the dependence of resistance on temperature differences in the room. This parameter works when the resistance is doubled relative to the standard value.
  3. There is a certain maximum voltage. If it is exceeded, there is a risk that the equipment will break.
  4. The parameters of the current load are divided into several types. Among them: nominal, switching, maximum and rollover. They are important if the posistor is used in a high precision circuit.

Attention! Before checking the item, you must wait until it cools down toroom temperature.

What malfunctions of a pharmacist can be encountered

You can determine the presence of malfunctions in an element by seeing a distorted image on the screen. This means that the element is highly magnetized. You can fix this problem by connecting the grid in series with the device. The grid is the outer loop that covers the inner surface of the screen.

The posistor is often soldered to the screen. Therefore, it becomes very difficult to check it without disconnecting from the TV. To take measurements, it is necessary to unsolder at least one part of the device from the grid. But the best solution is to completely remove the device from the system.

You can heat the posistor with a simple hairdryer. To check the operability of the device without heating it externally, it is necessary to assemble an electrical circuit. This will help determine the type of device. The instructions should say what voltage the element is triggered at and what temperature it can withstand.

You can determine the health of the device by heating it with a hairdryer. If an increase in resistance is noticed, then the element is working. But this method of verification has a drawback - the results may be erroneous. The problem is that the resistance of the parts of the assembled circuit can change over time, and therefore they begin to work unstably.

Another way to detect a malfunction of a posistor is to distort the image. It can ripple, or extra stripes appear. You can determine the performance of an element using a multimeter. It is recommended that the posistor be cold, as resistance increases when heated.

Another problem - contacts fell off. With constant heating of the posistor, they begin to wear out, and as a result disappear. Contacts may look normal but may not work. You can determine their performance using an ohmmeter.

If the posistor is broken or shorted, the first time you turn on the TV, the fuse will blow. If there is no short circuit in the network, it is necessary to turn off the posistor and check its operation.

Attention! Perhaps it is not the posistor itself that is damaged, but the element responsible for its cooling. We carry out a check.

How to fix it yourself

It is not difficult to find the device, it is located behind the back cover, next to the plug, which includes the demagnetization loop.

If the cause is magnetization of the device, it must be demagnetized. To do this, the device is unsoldered from the TV and connected to the demagnetization system.

But in most cases, damage to the device requires replacement. It is necessary to unsolder the old, and solder the new, similar in characteristics. If we choose the wrong device, it will not work.

Watch the video: LG crt tv,posistor problem (March 2024).

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