The Sinclair QL Forum

IMHO it will not work unless there is a common 0V reference (explains why your otherwise QL floating inputs to the Pico would cause problems). Just power up QL, Pico and VGA monitor from same switch.

ones' complement wrote: Thu Mar 23, 2023 11:43 pmIMHO it will not work unless there is a common 0V reference

Definitely! Lack of common ground would nicely explain the problems.

ones' complement wrote: Thu Mar 23, 2023 11:43 pmJust power up QL, Pico and VGA monitor from same switch.

That won't hurt of course, but there is no requirement.
All three devices may power up at different times.
(They won't power up exactly at the same time anyway, even if mains are switched simultaneously.)

Finally!!
I miss the line linking the GND at https://github.com/holmatic/video_if_ql_vga
I just added a small wire, there are several GND pins at the Pico that can be used.




Thanks to everyone that took a minute to read and answer helping me so much..