I spent last Saturday doing something that would bore 99% of retro gamers to tears—soldering a probe directly to the 74HC157 multiplexer on a VA4 Genesis/Mega Drive. Why? Because the internet has been lying to us about "zero lag" CRTs and original hardware.
Most people know the Model 2 Genesis has terrible, muffled audio. General wisdom says "recap the board." Technical Sega proved this was a partial band-aid. The author traced the issue to the mixing circuit between the YM2612 and the Z80. The solution? A 3-wire mod that bypasses Sega’s cost-cutting amplifier entirely. The post includes oscilloscope before/after waveforms. Technical Sega.blogspot.com
