October 19, 2021
Modifying a NES PAL Four Score to work with any region controller
This post describes modifications needed to make a NES Four Score PAL variant work with any kind of NES controllers. And, of course, the learnings supporting the modifications.
Why this? Recently bought a four score on eBay, but quickly learned that not all four score are built the same. The model received was a PAL or European model and this model is not compatible with North American or NTSC controllers. The North American controllers will not register inputs at the NES or to the game being played. Did not want to modify all existing controllers in possession and any or all future controllers that may be. Also, did not want to re-purchase another four score since already have one in hands.
The eBay seller advertised it as a model NES-034 and cleverly refrained from having a photo of the bottom of the unit. The PAL unit is a NESE-034 as shown below. Best course of action is to avoid these, but they're also sometimes cheap and you may want to pick one up to modify.
Click image to view higher resolution.
More info about how to modify it and background research after the click below.
The final result of the modification is shown below.
Click image to view higher resolution.
Table of Contents
- The modifications needed
- Four Score Architecture
- Differences between NTSC and PAL NES controllers
- Differences between a PAL NES and a PAL Four Score
The modifications needed
Disclaimer: If you follow these instructions then you are on your own. I take no responsibility for your actions and am not trained as an EE. If you break your NES, Four Score, controllers, your home, and/or yourself by following this then it is all on you.
Ingredients and tools needed:
- 5 (five) 2.2k Ohm resistors
- Soldering Iron
- Solder
- Flux
- Cleaning goods
Modifications needed:
- Add pull-up resistor to the downstream latch line
- Add pull-up resistors to each downstream clock line
Procedure:
- Take apart your four score
- Clean the board
- Add flux and solder to the old solder where you will be adding the resistors
- Install resistors
- Test
- Clean
- Put it back together
For steps 3 and 4 you can reference the photo below for the solder points. The resistors can be installed in any orientation. If you don't like these soldering points then you can tie the resistor between the controller pin in the diagram and any 5 volt source on the board. For example, controller 4 port is using an SMD resistor between the clock and 5 volt pins of the controller port itself.
Click image to view higher resolution.
One note about the resistor values. The PAL controllers and some NES controllers, such as the dog bones I have, use a 3.6k Ohm resistor internally on their Latch and Clock lines. Since the four score should be modified to work with all controllers (controllers with pull-up resistors and those without) a middle value resistance was selected and tested. Did not want to pull the line "too high" and fail to work because the IC can't pull it low due to having too much resistance.
Four Score Architecture
By now you have seen the back of the four score PCB twice, so here is a picture of the front part showing the controller ports, the IC, and some diodes and resistors.
Click image to view higher resolution.
The structure of the Four Score is that the product goes upstream to the NES and occupies two controller sockets. Then it goes downstream to four controller sockets where you plug in your NES controllers.
Each NES controller plug and socket has seven lines for communication, but two are not used by the four score. The five that the four score deals with are:
- Ground
- Volts
- Clock
- Latch
- Serial Data
For reference, the other two are data lines and are only used by special controllers such as the zapper gun and the Arkanoid Vaus. Controller pinout was referenced here (NESPi Project Part 4 – The NES controller port and protocol)
Unused lines were found on the PCB, but also read about in this thread here (http://archive.nes.science/nesdev-forums/f2/t10951.xhtml)
We do not need to modify anything upstream to the NES. Pretty sure nothing needs to be modified upstream for the PAL NES also, because it was originally designed to work with that. However, I don't have one here to test with.
Downstream controller ports receive a common ground, common 5 volts, and a common latch. Then they each have their own data line and clock line tied into the IC called FPA-PAL-SO1. That's all we need to involve with for this modification. For more information on the IC you can reference this wiki (FPA-PAL-S01 pinout).
A thread that did not lead to successful conclusion, but helped me to learn some stuff is shown here (Region Lockout on FourScoure).
Differences between NTSC and PAL NES controllers
The main difference between PAL and NTSC controllers is that the PAL ones have a pull-up resistor installed on the Latch and Clock lines. The value of these resistors are each 3.6k Ohm. Referenced from here (Standard controller PAL).
To research what needed to happen to modify the four score, I looked at how the PAL NES console deals with things and how people were modifying those to be universally compatible with any kind of controller.
On the PAL NES they have added a PCB between the controller ports and the NES board. This PCB has diodes which disallow electrical current in a direction, usually away from the NES.
The two sites referenced for the modification and images were here:
NES Controller Compatibility by Tetris Suomi
Modding an NES – PAL-E console controller support hack
Suomi's has good pictures of the PAL NES controller port from various angles and good advice on how to make compatibility in three separate ways.
Karios site has a good method for bridging diodes shown. Perhaps it isn't needed to bridge all the diodes as shown... Maybe just clock and latch will suffice?
Differences between a PAL NES and a PAL Four Score
Unfortunately, the architecture of the PAL Four Score's IC called FPA-PAL-S01 and the PCB it sits on does not match the PAL NES and the method to modify the consoles is not applicable to the four score. Bridging diodes on the four score causes no controllers to work anymore, since everything would just be routed through ground.