Parts kits now available

Digikey parts list has been updated 8/4/24 and is available to download in .xlsx format. Only 2 parts are different from the v1.5 B.O.M. Basic assembly guide available to download in .rtf format.

Upgrade and/or repair your 30+ year old Nintendo NES with this new design motherboard.

The NESessity is a top quality replacement motherboard for your front loader NES console with a variety of new features and easy customization options. Circuit is based on a complete reverse engineering of the original system and uses the original CPU and PPU chips for 100% pixel prefect gameplay and compatibility. Designed for easy assembly, all components are through hole (with the exception of two SOIC chips.)

3 circuit boards are included, the NESessity v1.5 motherboard and two versions of the A/V + power board. One has composite video only and the other has RGB, s-video, and composite connectors. RGB and s-video output is only available when building the NESessity with the NESRGB add on.

CPU and PPU chips are required to be de-soldered and removed from the original NES. Aftermarket clone chips are readily available from Aliexpress and can also be used (although these will have sound issues and are not compatible with some games.)

• CPU: RP2A03 (original) or UA6527 (clone)
• PPU: RP2C02 (original) or UA6528 (clone)

The NESessity is designed to install in NTSC systems. Building a PAL compatible system is possible by using the correct PAL CPU (RP2A07) and PPU (RP2C07) chips along with a 26.601712 MHz crystal.

Famicom games can be played by using a readily available cartridge adapter.

Features:

• Works and installs just like the OEM part in your original front loader console.
• Region free; Famicom games require cartridge adapter.
• 15p Famicom expansion port replaces the original 48p NES expansion port.
• Adjustable stereo sound with auxiliary sound input from NES cartridge pin 54.
• Can be assembled with or without original RF shielding.
• No lockout chip; uses reset circuit from top loader NES.
• PPU is in same location as original NES so any video mods that fit original will fit NESessity. Compatible with NESRGB and Hi Def NES video mods.
• Can use original AC NES power adapter or modern 12v DC power adapter.
• Includes no-cut A/V + power board with Genesis 2 compatible RGB video connector, s-video, and composite video. (NESRGB required)
• Power + A/V boards have isolated power and A/V ground for reduced interference.
• Works with original power / reset button PCB (requires LED polarity reversed on v1.4 and earlier.)
• Compatible with Famicom Light Gun, 3D Glasses, 4 player adapter, and BASIC keyboard. Some accessories may require a db15 extension cable to physically plug them in.
• Supports Famicom microphone and has LED to indicate when input is active.
• Ventilation holes for improved cooling.
• Premium quality PCBs have thick 2oz copper finish.

What's included with bare PCB?

• NESessity v1.5 motherboard
• two power + A/V PCBs (RGB and composite versions)

What's included with parts kit?

• All DigiKey parts listed in B.O.M. except optional IC sockets, LED, slide switch

What's required?

• Original NES CPU and PPU chips (recommended) or aftermarket clone chips
• Parts listed in B.O.M. Almost everything is available from Digikey
• (Optional) NESRGB kit for RGB & s-video
• Reused 5 pin power/reset connector from original NES
• The original front loader NES system case, cartridge connector, controller ports, power/reset board, etc.

Download and read the latest assembly guide before building your NESessity (located at bottom of page under "datasheet."

Assembly / Usage Notes:

• When using the Everdrive flashcart with NESessity v1.5, tap the reset button after power up and the game will boot normally.
• On NESessity v1.4 and earlier remove the 68p ceramic capacitor near the PPU to fix the menu glitches with Everdrive carts.
• All versions NESessity except v1.5 require removing the power LED and installing it with opposite polarity.
• Surface mount 10uF ceramic capacitor mounts on the solder side of the power / AV board near the 7905 regulator.
• If connecting a NESRGB v4 or IGR mod, set the correct reset jumper: All versions NESessity except v1.5 are reset when the "RST" pin is pulled low.
• NESessity v1.5 had a different circuit for resetting the console, which is closer to the original front loader NES. V1.5 is reset when the "RST" pin is momentarily pulled high, unlike all other PCB versions.

Thanks for looking!