Also from Portugal, and my first computer was a Timex 2068 too!
When I made my first scart cable i had the same problem (light gray image with flicker when reset). After rechecking the cable i saw a bad connected pin!...anyway some old scart tvīs need a 12v power supply thru the scart.
I built a Type 3 adaptor as kindly posted by Zetro here in this post and it works fine with all my scart LCD tvīs but not with my old CRT TV.
You may want to check this thread it if you havent done it already: