Updated 10 April 2019
This document only relates to the ZX Spectrum 128K ‘toastrack’ and the grey model ZX Spectrum +2.
THIS DOCUMENT IS NOT RELATED TO THE BLACK ZX Spectrum +2(A/B) or +3!
100% Correct cable circuit
Ian Priddey from Retro Computer Shack published his cable circuit for the toastrack/+2 (grey model) RGB cable: click here.
Where to find a correct cable?
The best RGB cables can be obtained at Retro Computer Shack (click).
More info
Here is the page of the ZX Spectrum 128 manual with the RGB connector pinout (click).
Here is the current version of my ‘ZX Spectrum video solutions’ document (click).
Credits
Credits go to Ian Priddey from Retro Computer Shack (click) for updating me with this solution!