What is CRT defocusing, how to deal with CRT defocusing, and how to find out

The cathode heated by the CRT CRT picture tube through the filament emits electrons, and under the action of the high pressure of the accelerating electrode and anode, it will fly to the phosphor screen in the form of an electron beam and bombard the silver powder to emit light. The electron beam is divergent, and the bright spots on the phosphor screen will be larger; And what we need is a small bright spot - the smaller the bright spot, the clearer the image, then we need to add an electrode in the picture tube, add a certain voltage to this electrode, so that the electron beam is gathered, adjust this voltage, so that the electron beam hits the smallest bright spot on the phosphor screen. This electrode is called the focusing electrode; This voltage is called the focusing voltage; The potentiometer that adjusts this voltage is called a focusing potentiometer.

When the TV leaves the factory, the focus is already set. Due to humidity and other reasons, sometimes this focusing voltage will change, causing the electron beam to diverge, which is reflected in the blurry image on the phosphor screen, and the brightness is also significantly reduced, which is the so-called "defocus". In actual combat, as mentioned by the upstairs owner, defocus is mostly caused by moisture in the CRT base.

The solution is to buy the same model of CRT socket and replace it, and then carefully adjust the focusing potentiometer (generally on the integrated high-voltage package, some European-style TVs, such as Telefunken, Gende, etc., use a split high-voltage package, focusing potentiometer ** circuit board), so that the image can reach the clearest. There are also problems with the focusing voltage and the focusing potentiometer itself, so that in the case of the integrated high-voltage package, the high-voltage package has to be replaced and the focusing voltage readjusted. As for how to find out, it is generally judged by the phosphor screen image, and professional maintenance does not quantitatively analyze the focusing voltage.

If the image is blurry when powered on. After a while, the image will slowly become clear or better, this is defocusing, the solution is to replace the header first, if not, change the high-voltage package (preferably the original), change the high-voltage package remember to adjust the focusing voltage. It's not a problem with the CRT.

Most of them are damp in the picture tube holder, and you can change the tube holder.

Looking at the problem, it is preliminarily judged that the picture tube is defocused, which is generally caused by the abnormal focusing voltage of the picture tube, and most of it is due to the dampness of the picture tube socket and needs to be replaced. 20 yuan to get it.

Of course, there is a problem with the picture tube,The current TV is very cheap,Because the picture tube TV is rarely repaired or basically no one repairs it,Replace it with a new one。

The tailstock of the picture tube is damp and rusty, and needs to be replaced.

It was preliminarily concluded that the CRT socket was broken.

This kind of TV also needs it, and now big TVs are so cheap.

Konka21Inch display tube TV has just been turned on and is blurry red,It took a long time to become clear,There are two possibilities for this phenomenon; 1) The defocus caused by moisture in the base of the picture tube must be replaced in order to completely solve it. 2) If you use a TV set for a long time, there will be a possibility of aging of the picture tube, so you can find a professional to remedy and repair it.

If the CRT is aging or defocused, it can be solved by increasing the accelerating pole voltage. "There is an adjustment knob on the high-pressure package".

The picture tube is aging and defocused. The old-fashioned machine consumes a lot of electricity, so forget about it.

If it's badly defocused, and there's a protected standby, it's a broken field, and I just fixed one.

Adjust the high-pressure focus to see if it works, or the tube socket is not matched! Then change the header.

1: The high-voltage packet is faulty (the focusing potentiometer on the packet is broken). 2: The picture tube is aging.

Has the high-pressure package been adjusted? Try it.

It is the oxidation of the focus line behind the picture tube or the poor insulation of the tube base. It is better to replace the header.

If the Changhong TV has been used for too long, it may be that the picture tube is out of focus, and the picture tube needs to be replaced.

49u3c is a liquid view TV,Just adjust it with a remote control,Look at the manual。

Have you ever seen a 49-inch picture tube?,Nonsense,This is obviously an LCD TV,