Website logo
⌘K
😀RetroSix Wiki
💡Learn Electronics
Byte Swapping (BIOS Files)
Digital Logic Levels
Video Standards
đŸ› ī¸Repair & Schematics
Power Supply Details
Amiga (Various)
Amiga 600
Atari 2600
Atari 7800
Atari Jaguar
Atari Lynx
Atari Lynx II
Commodore 16
Commodore 64
Dreamcast
Game & Watch New
Game Boy
Game Boy Pocket
Game Boy Color
Game Boy Advance
Game Boy Advance SP
Game Gear
Mattel Intellivision
Neo Geo AES
Neo Geo CDZ
Panasonic Q
PC Engine
PC Engine Duo
PC Engine Duo-R
PC Engine GT
PlayStation 2
Playstation 5
SNES
Sega Master System
Sega Mega CD
Sega Mega CD 2
Sega Mega Drive
Sega Mega Drive 2
Sega Mega-Tech Arcade
Sega Multi Mega
Sega NAOMI 2
Sega Saturn
Nintendo Switch
Xbox Original
Xbox One S
Xbox One X
Xbox Series S
Xbox Series X
ZX Spectrum 16/48k
ZX Spectrum 128
đŸĻŽInstallation Guides
Game Gear CleanScreen VA4/5
đŸ•šī¸Game Development
đŸ“ĻRetroSix Product Info
International Send-In Repair Service
📐Design Your Own
⚡CleanJuice Air USB-C Install (Game Boy Color)
đŸšĨLED Mods
đŸ› ī¸Send In Repair Service
đŸ’¯Prestige Shells & Consoles
🔋CleanJuice Battery Upgrade
🔊CleanAmp Audio Amplifier
🔍Glass Lenses
đŸŦOrdering & Shipping
Docs powered by Archbee
Repair & Schematics
Neo Geo AES

Jailbar Fix (Neo Geo AES)

3min

Some models of Neo Geo AES, such as the infamous 3-6 variant, suffer from Jailbars.

See the fix on my YouTube channel here.

Jailbars
Jailbars
īģŋ

This is caused by the 4MHz output of the Z80 CPU, and the 8MHz output clock of the Yamaha YM2610 sound chip master clock.

Z80 Clock
Z80 Clock
īģŋ
Yamaha YM2610
Yamaha YM2610
īģŋ

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.

Clocks Overview
Clocks Overview
īģŋ
Hex Inverter
Hex Inverter
īģŋ

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.

Clock Noise Pickup Point
Clock Noise Pickup Point
īģŋ

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.

Jailbar Fix
Jailbar Fix
īģŋ
Jailbars Fixed
Jailbars Fixed
īģŋ

īģŋ

Updated 01 Oct 2023
Did this page help you?
PREVIOUS
RGB CleanRGB Results (Neo Geo AES)
NEXT
Checkerboard Fix (Neo Geo AES)
Docs powered by Archbee
Docs powered by Archbee