!!! This is for the Build it yourself version, you have to supply the parts yourself !!!

Usually MBC3 chips only allow for 2MB of flash however by adding a special logic chip, we can extend the flash size to 4MB so you can future proof your RTC cart. There is an MBC30 chip which does support 4MB but carts usually go for $12-18 and aren’t very common where as MBC3 carts go for $1-3 and are everywhere. Re-flashable with any flasher like GBxCart RW that supports the MBM29F033C chip via the audio pin method.

As most users build MBC3 carts themselves, we’re providing this option so please ensure you know how to solder and you will need to source all the parts yourself (check the list below) and we will only provide the PCB and special logic chip (unsoldered). Please note that not all MBC3 original carts have an RTC, the most common ones that do are Pokemon Gold/Silver.

New v1.2 PCB allows for Rumble (supply your own motor, requires game patching to use, check example) and 2x 2MB ROM Mode which allows you to switch between 2 ROMs such as Gold/Silver to share the same save file (shell cutting/trimming is required to fit the switch, the shell won't close unless you trim the top part of the shell but be sure not to cut the little notch).

Build it yourself parts required:

• MBC3 chip (take from an MBC3 cart)
• MBC3 8 pin power management chip (take from an MBC3 cart)
• 4MB MBM29F033C Flash
• 32KB FM18W08 FRAM
• CR2025/CR2032 Battery holder + CR2025/CR2032 battery
• 32.768 KHz crystal (take from an MBC3 cart)
• 330K resistor 0603 (take from an MBC3 cart)
• 2x 20pF capacitor 0603 (take from an MBC3 cart)
• 1K resistor (take from an MBC3 cart)
• 10K 0603 resistor
• 10K 0805 resistor
• 4x 0.1uF 0603

For v1.2 these parts are needed for rumble:

• 47 or 100 Ohm 0805 resistor
• 2N7002 Mosfet SOT-23
• DSS115U SOD-123FL Diode (or any other 50V+ diode)
• Pager Flat Vibration Micro Motor DC 3V

For v1.2 these parts are needed for 2x 2MB ROM Mode:

• SPDT MSK-12C02 SMD Switch

You will need to modify the cartridge for the switch

How to use the rumble motor

You need to write the byte 0x20 to 0x4000-0x5FFF. Usually games write 0x08 but that would conflict with the RTC so you need to patch games to use 0x20 instead. For Pokemon Pinball we have an example patch to apply but it doesn’t appear to activate the rumble strong enough – you could lower the resistor if need be.

How to use 2x 2MB ROM Mode

Check the picture as you need to bridge jumper pads with solder and un-bridge another jumper pad. You’ll also need a special program to flash both ROMs to the cart: 2x 2MB ROM Mode Flasher.

Specs

• ROM: 4MB Flash (MBM29F033C)
• FRAM: 32KB (Data retention of 20-50 years)
• MBC: MBC3 original chip

The power consumption of MBC3 when powered from the battery appears to be around 2.3uA so a CR2032 should last around 7-10 years.

The PCB finish is ENIG.

If you will be installing this flash cart in an original shell, it is very difficult due to the CR2032 battery holder but it is possible, you can use a CR2025 holder and battery if you prefer.