For everyone who is not familiar with the Sega Saturn switchless mod here is some background information:
It originated from Sebastian Kienzl (Seb) who kindly provided the tutorial and code for this mod (http://knzl.de/saturnmod).
There you can read the details so I list only a short summary:
- You can switch between regions (PAL, JAP, USA)
- You can switch between 50 Hz and 60 Hz
- No visible modification from the outside
- All switching is controlled with reset button (normal reset still possible)
- Visual feedback of activated region (LED flashes in red, orange or green)
Here is what you will need for this mod:
- Soldering Iron
- Phillips screwdriver
- Box cutter
- 1x PIC 16F630 flashed with Seb’s code
- 1x duo-LED (red-green) with 3 legs
- 2x 220Ω resistors
- 1x Sega Saturn modchip V2
- Some wires (different colors are recommended)
- Soldering tin
- Solder braid (very recommended even if you have much experience in soldering)
- double-sided foam tape (not necessary but makes your life easier)
I oriented myself on the very good tutorials of wolfsoft and mmmonkey which were very helpful.
Please keep in mind that there are different mainboard layouts existing for the Sega Saturn. The priciple is always the same but the wiring of the jumpers that are responsible for region configuration could be sometimes a little bit confusing.
Here you can find a very good explanation of how the jumpers work. I strongly recommend reading and understanding them before you start:
After I unscrewed the console I looked at the mainboard:
It is very similar to the one that wolfsoft modded (http://wolfsoft.de/wordpress/?p=373).
You can use it in addition to this guide.
The main difference to the other kind of mainboards is that the controller ports are installed on a separate PCB which is connected with a ribbon cable to the mainboard
Ok, let’s start with the mod 🙂
The relevant jumper pairs for region settings are JP6/JP7, JP10/JP11 and JP12/JP13. They are labelled on the board.
Here JP10/JP11 and JP12/JP13 are located on the topside of the mainboard and JP6/JP7 can be found on the underside of the board. On other boards they could all be next to each other. Just keep looking! I am sure you will find them! 🙂
For each jumper pair there exist two common points which are connected together. One of the common points is connected to either +5V or GND depending on what region is pre-set. In my case it is a PAL console. You can find the common points easily because a wide trace leads to +5V and GND whereas for connecting common points to each other thin traces or 0Ω resistors are used. On my board thin traces are used.
First step is to cut the traces that lead from one of the common points to +5V or GND. I use a box cutter for this task. If the connection is established by a 0Ω resistor on your board you can simply heat it with a soldering iron and snap it away with the box cutter.
Here you see the wires soldered to the PIC and common points of the jumpers. The yellow cable leads to jumpers JP6/JP7 on the underside of the mainboard.
I had to cut the trace at the locations I marked because the region setting should not be „hard-coded“ anymore. Instead the PIC will setup and save the configuration for us.
Of course you also need to cut a trace at jumpers JP6/JP7. I modded about 10 Saturn consoles and this is specific jumper layout never crossed me before.
In order not to leave anything out here I show you where I had to cut the trace at jumper JP6/JP7. Please notice that at this jumper pair the right solder pad in each box is the common point whereas for the jumpers JP10/JP11 and JP12/JP13 they are the solder pads in the middle next to each other. It’s recommended to take a second look before you start cutting traces.
Now we need to remove the green power LED:
For that I recomment you to heat the two soldering points with your soldering iron from the other side at the same time and pull it out using some flat pliers. You want to avoid pulling it out with your fingers since the LED might become very hot. When it’s out you can shorten the legs of your duo-LED and bring it in position. I used double-sided foam tape for this purpose because it is highly adhesive and isolates at the same time. To be sure you can also put some insulating tape under it.
Our duo-LED has three legs. The one in the middle is for GND and the left and right one’s are for red and green flashing ability when they are connected to +5V. When bot are connected to 5V+ the LED will flash in orange color. This way we will have another color for each of three regions.
Soldering point for 50/60 Hz:
There are different ways to make the 50/60 Hz switching work. I use the method where you solder the cable to a pin of the graphics chip. It is easy to find because it is the only chip with 160 pins (40 in each row). That way it is also easy to identify pin 79.
Now comes the tricky part where you have to be careful. You will solder the pin off the mainboard and lift it up. Sounds scary? 🙂
It’s not that hard just make sure that your soldering tip is clean. I used a thin needle to get between pin 78 and 79 and lever it up while touching the solder pad on the mainboard with the soldering iron. When it’s done you can gently lift it in position with the box cutter like you see on the left side.
Instead of lifting up the pin you could also cut the trace in front of the pin 79 and then solder directly to the pin on the mainboard. But since there is not much space I still prefer to lift the pin and solder it to the cable. Wolfsoft used even another method although I wouldn’t say that it is easier. Take a look at his guide if you are interested in it.
After that I used some insulating tape and foam tape to insulate the pin and fasten the cable:
The next step will be to prepare the reset button the way that it functions as controller for the whole mod. Every function can be set and controlled by the reset button.
In order to achieve that we need to wire the reset button to our PIC (blue cable). Before we do it we have to cut the trace on the PCB that transmits the signal for reset function (see picture). From now on the reset button’s task will be to switch the regions and video mode. The best thing is that a normal reset will be still possible! Isn’t that cool?! 🙂
On the picture I made a mistake and soldered the brown cable to the wrong point. I marked the right one for you. You can simply follow the trace that comes from the reset button which we cut in the step before.
In the next picture you can see how the duo-LED is brought into position.
The red and green cables are soldered the left and right leg of the duo-LED and between them and the legs of the PIC we solder 220Ω resistors. The LED’s middle leg needs to be connected to GND. You can take it from any point on the edge of the controller port’s PCB. I marked them for you in the picture.
Now we have everything connected and we can assemble the console again like you see in the picture. I hope you remember which screws belong to which holes? 😉
Sega was nice to us and there are enough gaps in the metal cover where we can lead our cables along. You can also put the CD unit back on the spacers now.
Installation of the Mod chip:
The modhip that I installed is a V2 modchip bought from http://www.consolegoods.co.uk/. The owner of this site (Rob) is very nice and although he does not sell them officially on his site you can ask him by e-mail. I modded many consoles with his chips and they always worked like a charm.
This modchip works for CD units with 21pin ribbon cable. Personally I never had a Saturn with 20pin ribbon cable in my hands so the 21pin modchip should work for almost all available models. However, if you want to be on the safe side you can also order V3 modchip that supports both 20pin and 21pin.
Depending of your CD unit you need to prepare the modchip in a different way.
Please take a look at this guide in order to find the right way for your CD unit:
In my case I have to use the last method because my Saturn uses a 64pin CD unit.
Here you can see how I have to prepare the modchip for my kind of CD unit.
Then you need to solder a wire to the shown solder pad on the modchip and connect it to +5V power supply of your console. I chose to clamp it to the power supply because it’s easier and more comfortable if I decide to remove the modchip or dissemble the console if I’ll have to. Make sure to put enough solder tin on the cable before clamping it into the power supply in order to make it stay in position.
Luckily for us the power supply is well labelled so that we see where to get +5V from. In my case it’s the second from above. For your power supply it could be different. In most cases (if not all) +9V is on top and +5V is the second but there is no guarantee for that.
Lift the power supply up a bit off the metall spikes. Then push the wire into the clamp and push the power supply down again onto the metal spikes. Try to pull the cable a little bit to make sure it is clamped tight 🙂
Under the modchip I attached some insulating tape to the metal shield. You can also use a piece of card or plastic and put it under the modchip. I also used some of my beloved double-sided foam tape to keep the modchip in position.
That was it! We are done! You can now assemble your Saturn!
If you liked this tutorial, have some suggestions or questions please let me know.