Jailbar Fix (Neo Geo AES)
Some models of Neo Geo AES, such as the infamous 3-6 variant, suffer from Jailbars.
See the fix on my YouTube channel here.
This is caused by the 4MHz output of the Z80 CPU, and the 8MHz output clock of the Yamaha YM2610 sound chip master clock.
Specifically, after both of these clocks travel up to the SN74AS04 (Hex Inverter) which crosses over the RGB data lines, inducing the 4MHz/8MHz noise onto the screen.
You can see the clocks enter the hex inverter here. On the opposite side is the problem, where the RGB input traces run alongside these clock traces.
The fix is to cut the traces under the CXA chip side, as in this specific version (PAL) those traces travelling under the clocks are not even used.