It looks as though there is a problem with the Vblank interrupt from the VDP and CPU, hence the rolling down the screen. (could be a corroded trace maybe?) But yeah, next port-of-call would be the RAM. I doubt it's the cart slot, since most of those were simple ROMs, so it would likely have issues booting at all.
I was looking for an answer to this very question. I picked one up recently (UK) and it had no shielding and I was surprised. Looks like the US ones have shielding, I have watched a few tear downs and they all have it. FCC regulations maybe?
The Sega master system is a great console
It looks as though there is a problem with the Vblank interrupt from the VDP and CPU, hence the rolling down the screen.
(could be a corroded trace maybe?)
But yeah, next port-of-call would be the RAM.
I doubt it's the cart slot, since most of those were simple ROMs, so it would likely have issues booting at all.
I had one where it did this with the built in game and any game that used raster effects would go nuts
Just a small note: It's not a Mk1, it's a western version of the Mk3. But it's the first version outside Japan, so in a way it's sort of a Mk1. :)
I have an sms2 with the exact same problem, I put it away 5 years ago working fine and then I tried it out and it does what you show but even worse
mine has a shield
They don’t have shielding on them!
I was looking for an answer to this very question. I picked one up recently (UK) and it had no shielding and I was surprised. Looks like the US ones have shielding, I have watched a few tear downs and they all have it. FCC regulations maybe?