Scaling artifacts on CRT TV

Hi! I need help with Raspberry Pi 3, OSMC, Pi2SCART (aka gertVGA666) and a CRT TV. I’ve made a Smart CRT TV with OSMC and a RPi3 inside the chassis of the tv. It’s all fine beside the fact that i got scaling/digital artifacts that i can’t remove. I’ve tried the scaling kernel function in the file config.txt but nothing happened. The resolution i’m using is 2048x288p since i can’t get interlaced well on the Pi and since there are sync problems with the TV in other resolutions.

Do you need a log or more informations?

Thanks in advance