Introducing the NESessity NES front loader PCB replacement

[low_budget]

While I am no longer making the Super 8 bit, I thought I could put some of that knowledge to good use with a new project.

The NESessity is a top quality replacement motherboard for your front loader NES console with a variety of new features and easy customization options. The NESessity has all the features the Super 8 bit had, minus the Famicom cartridge slot. This kit consists of the new motherboard and a RF module/regulator replacement PCB (without RF.)

Everything fits perfectly in the original case. My first build was basic with only composite video output to ensure everything is compatible and functions correctly. The Famicom expansion connector is there replacing the useless original expansion slot, although admittedly it may be difficult to plug some things in without some kind of extension cable.

Designed for easy assembly, all components are through hole (with the exception of two SOIC chips.)

CPU and PPU chips are required to be desoldered 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 original part in your original front loader console
15p Famicom expansion port in the location of the original unused NES expansion port
Optional Famicom microphone support
Adjustable stereo sound with auxiliary cartridge sound input through pin 54
Can be assembled with or without original RF shielding
2 reset modes selectable with jumper: NES front loader reset (with screen blanking) or Famicom style reset (cpu only)
No lockout chip
PPU is in identical location to original NES so any video mods that fit original will fit here (such as NESRGB or Hi Def NES)
Can use original AC NES power adapter or modern 12v DC power adapter
RF module replacement board has room for larger heatsink on 7805 regulator (can also be used with switching regulator)
RCA connectors for composite video and stereo sound
Works with original power / reset button PCB
Compatible with Famicom accessories: Zapper, 3D Glasses, Family Basic Computer, and 4 player adapter (some accessories may require db15 extension cable)

[fernan1234]

This looks great!

I was disappointed to learn about the Super 8 bit too late after it had been discontinued, since my dream Famicom/NES setup is hardware that uses the original chips but offers clean video (no jailbars) and audio (no buzz). RGB is not essential, the original composite is fine and cool in its own right. So this looks like something that would fit the bill.

Unfortunately in my case I have a Famicom cart collection and a Famicom type Everdrive, so the abscence of a Famicom cartridge slot hurts, but I suppose there are workarounds. But does no famicom slot mean no expansion cartridge audio or FDS expansion audio support?

[low_budget]

The only reason a Famicom cartridge slot wasn't incorporated into the NESessity design is because it would be completely impractical to do so using the original NES case. Not impossible, but it would require major case modifications, an additional PCB, and lots of extra wiring which would go against my design goal of a drop in PCB replacement.

Expansion audio is supported through NES cartridge pin 54. A Famicom to NES adapter with this connection would support it, as well as NES flashcarts that output auxiliary sound to pin 54. Hyperkin makes an adapter: https://www.amazon.com/Hyperkin-Adapter ... B076CBJ3GP I have not tested it so I don't know if it has the expansion audio connection (although it should be easy to mod if it doesn't)

I would have preferred to make a top loader NES replacement PCB, but with the controller ports being unavailable along with the much lower production numbers of top loader NES systems I decided that would not be worth the effort.

[unabletoconnect]

Hey,

Just wondering if their has been any progress sorting out the booting issue?

[low_budget]

I am still working on the NESessity PCB design.

Unfortunately the v1.0 NESessity was not working correctly. Namely, the system won't boot. While I did test the v1.0 board, I found it only showed a grey screen. Then I remembered the PPU chip I was using was bad, and (wrongly) attributed the problem to the PPU. I did some more checking of the design and went through every connection, and it was all correct. I did not have a confirmed working PPU chip available at the time, and I (stupidly) assumed the v1.0 NESessity would work fine if used with good CPU / PPU chips.
When I did get working CPU / PPU chips to test, I realized the v1.0 had other issues.

So I just sold 8 PCBs and now realized none of them would work, so I notified everyone not to assemble them and refunded the cost. A couple people were really quick and had already assembled theirs, so I will work something out with them. I hope to find a fix to make the v1.0 PCB work, but it's looking like a new PCB design will be necessary.

So yes the v1.0 NESessity was rushed, and I didn't do thorough testing.

I'm currently working toward having the new NESessity v1.1 PCB design ready this fall.

[ldeveraux]

Thanks for being honest and transparent, especially in a time when it may be difficult to do so.

[low_budget]

It turns out the v1.0 NESessity was not booting because of a simple grounding error. The OE pin of U1 WRAM wasn't connected when it should be grounded. This means the WRAM was never enabled. On the VRAM chip, OE isn't grounded, so I guess that's how I overlooked it.

It should be possible to get v1.0 NESessity working by simply bridging pins 22 and 23 together on the U1 WRAM chip. I will be testing this out soon.

I've made many improvements to the new v1.1 NESessity design, which I hope to have available in September. I will be testing everything thoroughly so absolutely no problems this time.

[low_budget]

Success

So OE of the WRAM chip not being grounded was the only problem with v1.0 of the NESessity.

There were no issues with the clock circuit or the reset circuit as I had suspected earlier.

I've learned a lot from v1.0 and have improved the PCB layout and dimensions on the upcoming v1.1 NESessity while incorporating some bug fixes.

[low_budget]

I have assembled and begun testing of the v1.1 NESessity. I didn't use any video mod on this first build, just composite video.

Everything was working great with only one (minor) issue: the heatsink for the 7805 regulator gets quite hot when I tested with my PowerPak. I know this is also an issue with the original NES, but I was hoping to solve it by using a massive heatsink made of 1/8" thick aluminum c channel.

I just replaced the 1.5A 7805 style linear regulator with this https://www.digikey.com/products/en?key ... -2196-5-ND more efficient and cooler switching regulator. This is what I used in the Super 8 bit, and I never had issues powering a system with NESRGB and high load cartridge like the PowerPak.

My next step will be doing a NESRGB installation in a NESessity equipped NES, while figuring out the best way to do so. The NESessity won't need the additional 5v regulator included with the NESRGB. There is also a SPDT switch that can be used for palette selection where the original RF channel select switch was.

Version 1.1 of the NESessity has the following features over v1.0:
- Many bug fixes
- Thicker 2oz copper layer
- Improved component footprints

[VajSkids Consoles]

How’s this different to OpenTendo ?

[low_budget]

How’s this different to OpenTendo ?

The OpenTendo is a near exact replica of the original NES motherboard. It has small changes like expansion audio support and is updated for modern replacements of obsolete components, but is otherwise functionally and visually identical to an original NES motherboard.


The NESessity design is based off the Super 8 bit, which was based off a reverse engineering I did of the original NES way back in 2012. The NESessity is electrically identical to an original NES in all the ways that matter for 100% accurate gameplay.

The NESessity has the following changes and new features over an original NES:

- Lockout chip gone. Replaced with simple NES top loader reset circuit. (no blinking red light ever)
- A second PCB replaces original RF modulator/ 5v regulator circuit and removes RF completely.
- Adjustable stereo sound circuit with expansion audio.
- Improved composite video amplifier.
- 15p Famicom expansion port in place of the original 48p expansion connector.
- Famicom microphone circuit


I will have these available on Tindie.com very soon. http://www.tindie.com/products/low_budg ... rod_search

[fernan1234]

- Improved composite video amplifier.

This sounds interesting. Could you share more detail on how this feature is reflected in the picture output via composite connection?

[ldeveraux]

Wow only $40, seems like a no brainer. But I've RGB modded my NES, so seems like it wouldn't be feasible.

[RGB0b]

I'm pretty sure that switching 7805 replacement causes diagonal jailbars. We've tested it on NES and SNES consoles and while it doesn't require a heatsink, it caused more problems then it fixed.

Will that be $44 for board-only, or for something fully populated...but without the CPU and PPU of course?

[Bratwurst]

I'm pretty sure that switching 7805 replacement causes diagonal jailbars. We've tested it on NES and SNES consoles and while it doesn't require a heatsink, it caused more problems then it fixed.

Will that be $44 for board-only, or for something fully populated...but without the CPU and PPU of course?

If you had clicked the Tindie link you would have found:

Bare PCB set with Digikey parts list

can be used with 5v switching regulator or 7805 style linear regulator.

The design looks great. I could see revising the RF/Power module board with 8-pin or 9-pin minidin sockets for NESRGB access without having to drill any additional holes in the casing.

I do think dual wipe sockets should be used in place of machine pin sockets for the PPU/CPU. Better contact to surface area, easier to rework/replace later. My only other remark is that metal hooded connectors (in this case the DA-15 socket expansion port) can sometimes shear the plastic around the plug depending on dimensions of the socket or user carelessness.

[low_budget]

I have uploaded schematics for the NESessity / Super 8 bit to atariage: https://atariage.com/forums/topic/20325 ... /#comments

Here is the composite video amp I am using: http://jpx72web.blogspot.com/2016/11/fa ... d-new.html

I have seen other composite video amp replacement circuits for the NES but they are basically the same, just different resistor / capacitor values are used. If somebody wanted to experiment and try other composite amplifier circuits it would be easy to swap different components.

While I say composite video quality is improved over an original NES, that still doesn't mean it's great. It's still generated internally by the PPU, and there is only so much an improved amplifier with no RF circuit can do. There are still some faint jailbars. For the best composite video quality use a NESRGB.

One of my goals with the NESessity was to make the design flexible with many different ways to build it. The B.O.M. included with the NESesstiy has part numbers for both types of 1.5A 5v regulators, switching and linear. It also has the part numbers for both types of DIP 40 sockets, dual wipe and precision.

As for the metal shell of the 15p Famicom expansion connector, I simply could not find any plastic option.

I was considering adding a mini DIN 8p or 9p connector for RGB in the original RF location; I would have to see if there is much demand for that. It would be more expensive to order PCBs for both options. I personally don't mind drilling holes in front loader NES cases since they are pretty common.

I am still experimenting with different heatsinks for the 7805 linear regulator. I have never had it thermal shutdown before, even after an hour of play, but it does get really hot. I'm just using the switching regulator for now in my NESessity test system.

[fernan1234]

For the best composite video quality use a NESRGB.

Do you mean when composite is encoded from RGB rather than getting it from the PPUV pad on the NESRGB? In my experience while the RGB-derived composite is cleaner with less dot crawl, it's also noticeably less sharp than the original composite, and you're also at the mercy of the color palette dilemma. Also if the console has jailbars, they will show on a NESRGB installation regardless of whether its PPU composite or RGB-derived composite.

[low_budget]

I have always had good results with NESRGB composite video, but I have never done any in-depth comparison with regular composite.

I am building a second NESessity system, this one with a NESRGB install. I like clean installations, so I'm trying to determine the best way to do the video output wiring and connectors.

While I have heard suggestions to put a mini-DIN connector in place of the rear RCA connector, I think maybe a separate PCB with s-video and RGB connectors will work well and allow for a clean installation. This could mount to the rear of the NES with 2 screws (4 holes total.) I don't like the look of panel mount mini DIN connectors and don't want to glue connectors into place like the NESRGB instructions suggest.

I have also found a better heatsink for using the 7805 regulator. I make periodic changes to the BOM based on parts availability or if better parts are found.

Here's how everything looks with the CPU/PPU and NESRGB installed.

[BazookaBen]

Will this line up correctly with a Blinking Light Win?

[low_budget]

Will this line up correctly with a Blinking Light Win?

Yes the blinking light win or the original spring loaded cartridge tray fit perfectly with the NESessity PCB. The outer dimensions as well as hole locations / sizes are identical to an original NES PCB. The only change I made was a cutout where the old RF box used to solder directly to the motherboard.


I'm trying to decide if I should offer assembled NESessity PCBs (minus CPU & PPU) or kit with PCB and all BOM parts included. The assembled PCB would still need the CPU and PPU, so it still wouldn't be a "drop in" installation, so maybe kits would be better?

[Eames]

Got my NESRGB with the IGR finished up. With the CPU socketed the NESRGB board won't quite seat all the way but it's in enough. I'd probably skip the socket if I did it again. Used the extra header for getting audio off the board instead of through the NESRGB. For the IGR reset in / out I cut the trace on the other side so I could use the original wiring for RIn and the extra unused resistor spot for ROut.

I haven't done any extensive testing or comparisons but it looks good to me. The only thing I'll revisit is the regulator heatsink. I'd like to have it mechanically secured somehow but haven't come up with how yet, maybe I'll move it off the power board. Other than that everything went together great, thanks for making the boards low_budget!

[WinManX2000]

Got my NESRGB with the IGR finished up. With the CPU socketed the NESRGB board won't quite seat all the way but it's in enough. I'd probably skip the socket if I did it again. Used the extra header for getting audio off the board instead of through the NESRGB. For the IGR reset in / out I cut the trace on the other side so I could use the original wiring for RIn and the extra unused resistor spot for ROut.

I haven't done any extensive testing or comparisons but it looks good to me. The only thing I'll revisit is the regulator heatsink. I'd like to have it mechanically secured somehow but haven't come up with how yet, maybe I'll move it off the power board. Other than that everything went together great, thanks for making the boards low_budget!

Hey, what did you do to get the RGB to exit your shell? I am hoping for a version of the power supply PCB to accept a multi out connection. This would make for the cleanest install yet. The only wires needed to be hooked up would be RGB and CSYNC as the audio would pass through the existing L/R mainboard to the multi out.

[low_budget]

Nice assembly work Eames. Where did you get the shielded wire you used for RGB connection?

I didn't know about the IGR until I read your post. I'm curious why you connected some of the wires directly to the CPU when the 3 pins are available on the P1 controller connector.

The CPU should be soldered to the motherboard when using the NESRGB. I like to put ICs in sockets when possible, but there just isn't enough room with the NESRGB.

The stock NES heatsink is inadequate for powering a NES + NESRGB in my opinion. I recommend Digikey part HS346-ND
When I release a new version of the NESessity, I will incorporate mounting holes for a heatsink.

[WinManX2000]

When I release a new version of the NESessity, I will incorporate mounting holes for a heatsink.

I am super interested in this. Have you thought about making provisions for the secondary I/O board to accommodate a SNES multi out? This would make this solution the perfect project IMO. Stereo amp with proper mixing, NESRGB for proper RGB out, all funneled into the multi out.

[Eames]

The shielded wires are from a VGA cable. For the IGR install I didn’t know all the needed pins are on P1, I was going off the brief install photos on the IGR’s GitHub repo.

[Eames]

I ended up mounting the heatsink to the top shield. After an hour with the top on and using the original wall wart (9VAC) it's hot but not too hot to touch. I measured about 450mA draw on the 5v output with NESessity + NESRGB + IRG + Everdrive.

[mrsmiley381]

I'm trying to decide if I should offer assembled NESessity PCBs (minus CPU & PPU) or kit with PCB and all BOM parts included. The assembled PCB would still need the CPU and PPU, so it still wouldn't be a "drop in" installation, so maybe kits would be better?

My soldering skills appear to have degraded over the years despite having access to better tools so I certainly would appreciate a mostly-assembled kit.

I looked at your schematics a bit but I'm not too savvy on hardware design. Does this have the wiring necessary to allow a Zapper on both controller ports for games that have the option? I think Chiller is the only one that supports two Zappers at once and there's another unlicensed game that will allow it on one or the other. Just curious since you managed to solve the major edge cases by implementing a microphone on the board.

[low_budget]

The shielded wires are from a VGA cable. For the IGR install I didn’t know all the needed pins are on P1, I was going off the brief install photos on the IGR’s GitHub repo.

Nothing wrong with tapping directly into the CPU, but it pins 2 - 4 on controller port 1 could also be used. It looks like that would be:
CK - pin 2 - also connects to CPU pin 36
LT - pin 3 - also connects to CPU pin 39
OT - pin 4

Using the RF shield as a supplementary heatsink is a good idea. I had to trim some of the top RF shield to make room for the heatsink I am using in my install.


The controller ports are identical in function to an original NES. 2 Zappers can be used in Chiller.

I will likely offer some kits and some assembled NESessity boards sometime later this year.

[friedskater]

I completed my NESessity a few weeks ago and it has been working well. I used the switching regulator and added the NESRGB. There is some very slight noise on large areas of color through the OSSC which I'm attributing to my PSU (a different PSU I tried does not have this noise), but otherwise it's great.

Today I got an Everdrive N8 Prro but there are graphical glitches on the N8's menu screens. The games themselves run fine. My PAL console with its original motherboard and NESRGB doesn't have these glitches with the same N8. Any ideas?

I didn't fit the NESRGB voltage regulator in either console.

I have a new "higher quality" PSU on order from oldskoolconsoles, to see if that helps. Although I've tried some other 9V-12V adaptors that I had around the house and get the same issues. The Everdrive diagnostics all pass and it says VCC is about 4.6V on both my NESessity and PAL decks.

I'm consider swapping out the switching regulator for a 7805 as a test, once I source a suitable heatsink.

Should I be trying anything else?

[friedskater]

So I took out the NESRGB and ran the NESessity with just composite video - and got the same result. Official carts work fine, N8 Pro has corruption on the menu. Note that ROMs work fine from the Everdrive. It's only the menu. The same N8 works fine in a PAL frontloader.

Here's a video of the glitches.

https://imgur.com/yTeOOMj

I'm also thinking about swapping out the 74LS latches for the 74HC versions.