Here’s a controlled undervoltage experiment on a Sega Mega Drive 2.

I’m using an adjustable DC-DC step-down converter to gradually reduce the supply voltage and watch what the console does.

As the voltage falls, the machine starts producing increasingly strange behaviour.

The reason this interested me was the earlier Aiwa Mega-CD troubleshooting.

During early Aiwa testing, the Mega Drive side had shown some superficially similar symptoms when it was not receiving enough voltage.

That does not mean similar-looking video corruption always has the same cause.

What it does demonstrate rather nicely is that a bad supply rail can create symptoms that look suspiciously like logic or video faults.

Measure the boring voltages before blaming the exciting custom chips.

Enjoy!