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
CR2032/CR2025 Battery holder + CR2032/CR2025 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.
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, Gold fingers (on the edge connector) with a 45 degree bevel to give the maximum life for insertion/removal of the cartridge.
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, some users prefer using a CR2025 battery holder instead.