WG D9200 - intermittent blurring, replaced flyback to no avail

[JJKallday]

Hi all,

I have a 27" WG D9200 series monitor that is suffering from a frustrating issue. When powered on, it will gradually blur until text is unreadable until it will suddenly "snap" back into focus. Once it is back in focus, it immediately starts the gradual blur process again. Tonight, an entire cycle of this was taking about twelve seconds.

The flyback was replaced yesterday. On the old flyback, I tried adjusting the focus knob in hopes of fixing the issue, but the only stable picture that I could get would be a 100% blurry one. After a couple of months of adjusting the focus knob from time to time, it suddenly sparked and gave me a painful shock while I was adjusting it one evening. Now that a new flyback has been installed, I'm cautious about touching that knob ever again. (Side question: is there a limit to how far the focus knob can or SHOULD be turned?)

Any help would be appreciated. Thank you.

[obcd]

The focus and screen are normal potmeters. You can rotate them approx 270 degrees. You can easily feel that you reached one end or the other.

I have read about people that had an oxidated focus wire connection on the crt board that caused such issues. Sometimes the wire is just clamped and not soldered on the crt socket side.

If you turn up the screen voltage 2 much, it's possible that the xray protection will shut down the monitor chassis.
Your picture will be all white before this happens, but I had it once with a new flyback that had that screen adjustment on it's maximum.

For most other faults, you would expect the brillance of the picture to change as well.

In worst case, it can be a bad contact of the focus pin in the tube as well, but I would check it's solderings and connections first.