Wavy distortion on Trinitron TV

[Professor Jones]

I just bought a Sony KV-21CL10B for a dedicated groovymame PC and after some fiddling with the settings I'm getting a very nice picture. However, something is bugging me : there is at all times (no source/any source or resolution) some sort of wavy distortion on the image. This is especially apparent on the contours of white letters on a black background. I tried to capture this on video (this is just the OSD of the TV, it seemed to be the easiest way to show it on film) :

https://photos.google.com/share/AF1QipOXksXdn9gHBBavIyExYJqJj57GNFe1T2PYfK2RhYvk9igDAqEFSYdAvmkXqASotg?key=ZVFuYlJuTEU3b003dThzQzFjbVBZdUpkT1Y0NmtB

How can I get rid of this ?

Thanks !

Edit :

Here's another video : https://photos.app.goo.gl/FrFkgVAeu4NbTgDT7

I did an additional test : I shut off all the electrical equipment close to the TV and the problem was still there. It's reminiscent of the noise you get when you have a low quality RF signal. It's like there is white noise underneath the picture.

[nipsmg]

Does this only happen when the computer is attached?

I had the same problem on my trinitron.  Turns out it was caused by dirty power -- Crappy PC PSU.  I replaced the PSU, nice CLEAN, clear picture.

[Professor Jones]

Thanks for your suggestion, in my case the problem is present even when the TV is plugged in by itself without any other electrical device close to it, in any room of the house. That seems to indicate that the source of the problem is internal.

[big10p]

Maybe a cap needs replacing. Possibly the main power smoothing cap? Just guessing here, really.

[Professor Jones]

I opened the TV to visually check the caps, and they all seem fine, with no sign of deformation on the top or leaking.

Could this be caused by the tuner picking up frequencies ? Would it be possible and beneficial to deactivate it since I will never use it ?