Neotec drifting focus and brightness (screen) issue.

Breakdown in focus / screen voltage divider causing blurry display

The Neotec series of monitors are commonly exhibiting an issue where the screens brightness and focus drift as the monitor is running.  The user will see the screen getting brighter and blurry as it runs. If the user dials in the screen and focus after the tube has been warmed up it will only drift again rendering the picture unclean / blurry. This is mostly noted on the older worn out zenith tubes. I am now starting to see this symptom in the rca. The only known cure to have been found is to replace the fly back with a BRAND NEW valid replacement flyback. With a new flyback unit the HV holds stable resulting in a clean, sharp & bright image. I have noticed that with the stock flybacks HV reading at the anode terminal is lower than the desired 28kv. I usually see it around 22-24kv in the worn flybacks. When a new flyback is used the hv is significantly higher by about 4-6kv giving hinting that the old worn flyback has breakdown in the focus & screen voltage divider.