From the principle analysis, the main cause of this phenomenon lies in the focus circuit, but also may be caused by poor heat dissipation. First of all, because of the problem of focusing circuit design, resulting in long-time use can not ensure its normal work, resulting in blurred image, and second, due to poor heat dissipation, resulting in too hot pipe, the formation of output power loss, and then affect the high voltage output and acceleration level voltage output is not enough, thus affecting the normal operation of the focus circuit. In fact, it is still the problem of focusing on the circuit. Workaround: Turn on the back cover of the monitor, which has a knob that adjusts the high pressure. However, this scheme is only effective in the short term, long time the display in the case of adjustment of high pressure will accelerate the aging of the display, a long time will still produce poor focus situation.
If the monitor has been in service for years, it can give it the last heat of its life; however, if it is a newly purchased monitor, it must be replaced as soon as possible.