Picasso IV display issue

[zipper]

Try pushing down on the chips that are socketed. Failing that it may need recapping (Replacement Caps).

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My opinion, too. One of them is the FliFi chip.

[zipper]

The native modes can be flicker fixed up to 120 / 150 Hz by using software to tweak and flash the board. But also 50 / 60 Hz may be chosen during the boot time.