Dell D1626HT monitor wavy lines

[scrungy_doolittle]

I like my big old monitor, but recently it has started exhibiting strange behavior. I suspect it is a cap.
I found the schematics online, so I have them.
The symptom is as follows.
The sides of the screen have squiggles. NOW:The strange thing.
On a normal TV when this happens, some of the scan lines are shifted to the right, and the left edge follows them. In THIS case, the wiggles are on both sides of the screen , BUT they are symetrical. That is, if on the left side of the screen, the scan line starts a 1/2 inch toward the middle, the right edge of the screen will be 1/2 inch toward the middle. It's like the scan line shortened from both ends, centered on the screen.
The wavy edges are opposites like the middle of an hour glass, rather than wiggling in paralell.
Does anyone have a clue where I should be looking for this problem.
This distorts the entire screen, and the wavy pattern is not static.
I.e. it shifts some.
cheers

[torbjorn]

It is a well known type of problem with some kinds of monitors. In the past, i have encountered it on Nokia 449 series as well as on some old AOC EGA monitors.

If the monitor has the horizontal deflection separated from the EHT supply, then the width control and E/W correction is usually done by controlling the supply voltage to the horizontal deflection output stage.
If now this control is done by a step-down voltage regulator that does not run in sync with the horizontal deflection, such "wiggles" in the line length will occur if there is not enough filtering between the regulator and the horizontal output.
So, check the electrolytics connected to this supply line!