How to check a posistor on a TV

A posistor is one of the parts of the system that is responsible for demagnetization. With high magnetization, the TV image is distorted or stripes appear. Their appearance means that the device has failed. It is necessary to check its functionality. If necessary, the posistor is repaired or replaced.

How to check a posistor on a TV

A posistor and a resistor are elements that can change their resistance when heated. Resistors experience slight temperature increases. A posistor blocks the electrical voltage supplied to it, so its temperature can rise significantly.

To check the posistor for performance, 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 only works at normal room temperature (not lower than 18 and not higher than 27 degrees).
2. Resistance is determined by a point that characterizes the dependence of resistance on temperature changes in the room. This parameter operates when the resistance increases to twice the standard value.
3. There is a certain maximum voltage. If it is exceeded, there is a risk that the equipment will break.
4. Current load parameters are divided into several types. These include: nominal, switching, maximum and rollover. They are important if the posistor will be used in a high-precision circuit.

Attention! Before checking the element, you must wait until it has cooled down to room temperature.

What pharmacist malfunctions can you encounter?

You can determine if there is a fault 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 mesh is the outer loop that covers the inside surface of the screen.

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

You can heat the posistor with a simple hairdryer. To check the functionality of the device without heating it externally, you need to assemble an electrical circuit. This will help determine the device type. The instructions should state at what voltage the element operates and what temperature it can withstand.

You can determine if the device is working properly 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 unstable.

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

Another problem is that the contacts have fallen off. With constant heating of the posistor, they begin to wear out, and as a result they fall off. The contacts may look normal on the outside but not work. You can determine their performance using an ohmmeter.

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

Attention! It is possible that it is not the posistor itself that is damaged, but the element responsible for cooling it. We are checking.

How to fix it yourself

Finding the device is not difficult; it is located behind the back cover, next to the plug, which includes a demagnetization loop.

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

But in most cases, damage to the device requires its replacement. You need to unsolder the old one and solder in a new one with similar characteristics. If we select the wrong device, it will not work.