I changed the PSU because I had only a black screen when starting the NeoSD, I bought a new PSU, it is a new 5v 3A dedicated to the Neo Geo, manufactured by a game shop:
https://www.tradergames.fr/en/snk/alime ... 79184.html
Now the NeoSD menu appears, but it still show some issues.
When flashing a game, the screen switch to black (but the TV always detect the signal). After some time, the screen shows some weird patterns and usually finish with a blue screen. Sometimes it stays blue, then I reboot the console few seconds after and the game launches (mainly with small game). Sometimes the screen flickers and it doesn't conclude to a playable game.
You can see on video:
What could we do ?