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I have two Panasonic 3DO FZ-1 consoles, and one of them developed a problem. A technician suggested the faulty component might be a thyristor (SCR), so I replaced it with a TS820-600B.

The console now powers on and displays the 3DO logo, but then gets stuck on a black screen.

I've tested two known-working ODEs, replaced the ribbon cables, and checked the power supply to the Raspberry Pi Pico: 5V and 3.3V are both present.

The USB flash drive LED blinks, but neither the console's ACCESS LED nor the Pico's LED ever flashes, unlike my working FZ-1.

Has anyone experienced something similar? Could the SCR replacement be related, or should I be looking at the CD-ROM interface circuitry or another part of the motherboard?

Any suggestions would be greatly appreciated!