Atari 520 STM with video issue (bars and waves)

[PilgrimST]

Hi all,

I wonder if someone could help me.
I have an Atari 520 STM with 1MB RAM upgrade and TOS 1.04, it is connected via SCART cable to a SAMSUNG LED TV / Monitor.
The green background colour of the desktop has a wavy pattern, all games show "jail bars". The black and white image looks
good, the same for monochrome via VGA cable. Could someone kindly tell me what the issue may be?

I have tested the 520 STM via TV Modulator the outcome was the same.
I have also tested on different monitors, the image looks (almost the same).

Thank you in advance!

[exxos]

AFAIK its actually a "pattern" on the desktop, its pretty normal to see it. If you really wanted to test it out, try some solid RGB colours on a paint program.. or you might be able to change the desktop background in control panel somewhere..

[PilgrimST]

Thank you for your reply. I have connected my 520 ST to an old Sony Trinitron CRT. Now it looks pretty cool
It really depends on the screen, and yes it could be a pattern too.

[KyleB]

Isn't TOS 1 just solid green? The pattern came in by default in 2