2024

What should I do if I can't see clearly or blurry through the variable light screen?

Sometimes our display will appear blurred, this situation is more common, encounter such a situation, if we encounter the display blurred fault how to deal with it?

The vague display indicates that the picture tube is not focused well. The main reason for the poor focus is the aging of the picture tube, or the anode high voltage is too low, or the Focus (focus) voltage is incorrect.The inspection should be carried out from the following aspects:

1, check whether the picture tube is aging, for the general maintenance, due to the lack of special equipment, can only use indirect methods, the specific approach is:

Switch the tube brightness potentiometer to the maximum, power up the display and observe the grating. If the grating appears for a long time and the brightness is insufficient, the picture tube is aging. If the grating appears for a normal time (compared with a normal display), the picture tube is not aging. Sometimes slight air leakage or interelectrode ignition of the picture tube will also cause poor focusing. For the inspection of air leakage of the picture tube, the neck part of the picture tube can be observed. When the phenomenon of "fog filling" is found in the neck of the picture tube, it indicates that the picture tube is leaking. Check whether there is a spark between the electrodes of the picture tube. You can directly observe the display of the fluorescent screen. If the displayed content is fuzzy but stable, there will be no spark between the electrodes of the picture tube. The inspection of the fault shows that the picture tube is not damaged.

2. The anode high voltage can be directly measured with a high voltage meter. If there is no high-voltage meter, never use a multimeter to directly measure the anode high voltage. Commonly used methods are:

(1) When powering up the display, pay attention to whether there is any obvious high-voltage charging sound in the deflection coil. If so, there is generally no big problem with high voltage: if not, it means that the display has no high voltage or insufficient high voltage.

(2) After powering up the monitor, gently touch the screen with your hand to see if there is any "pop" static discharge sound. If there is, it means that the voltage is basically normal. If there is no or static discharge is not obvious, it means that the display has no high voltage or insufficient high voltage. The anode voltage of the picture tube is basically normal after inspection.

3. Check the Focus voltage. Adjust the focus potentiometer (on the line output transformer) of the picture tube. The display content is clear as before. After less than half a day of use, the fault phenomenon reappears. After inspection, it is found that the focus potentiometer knob is fixed with silicone rubber, which has strong elasticity. After the potentiometer is initially adjusted, it is not fixed again. After a period of time due to elasticity, the silicone rubber pulls the potentiometer back to its original position, so the fault phenomenon reappears, re-adjust the potentiometer and fix it with epoxy resin, and the fault will be completely eliminated.