Since the most questions people send me are about VRC4 repros I think its handy to have a dedicated post for some infos about them 🙂

If you want to convert a VRC4 game into another you need to rewire the VRC4 in some cases. Have a look at this chart:

If you don’t know what VRC4 board revision you have and the game you’re planing to do, have a look here: https://wiki.nesdev.com/w/index.php/Talk:VRC4

Please note that the letter after VRC4 does not mean a revision of the IC but rather revision of the PCB!

You rewired everything according to the chart and the screen still looks garbled?
You may need to remove or add some components to the PCB, namely a 1K resistor, a 1N4148 diode a 2K*8 SRAM 150ns (or faster) IC and a ceramic capacitor.

The SRAM needs to be pin kompatible with the MB8416A-15LZ:

These are the components that need either be removed or soldered in:

Games needing these components:

• Crisis Force
• Ganbare Goemon Gaiden 2: Tenka no Zaihou
• Gradius II
• Parodius Da!

Games that need these components removed:

• Bio Miracle Bokutte Upa
• Racer Mini Yonku: Japan Cup
• Teenage Mutant Ninja Turtles I & II
• Tiny Toon Adventures
• Wai Wai World 2: SOS!! Paseri Jou

I think that should cover all questions 🙂 If not, just drop me a mail through the contact form, I’m always happy to help,

PS: Feel free to copy and share the info 🙂