Sega Saturn Switchless Region and Video Mod

Sega Saturn Switchless Region and Video Mod

I have already linked to Sebs Ultimate Sega Saturn Mod, it’s a fantastic mod, it really is the best Saturn mod and leaves you console looking untouched!  Completely switch less control over the Region and Video mode settings.  I’m not going to rewrite Sebs guide, all the info you need is already there.

Once installed and easy to control all via the Reset button:

Quick press – Reset the Console

Hold for about 1 second, the Power LED will turn off, release to swap between 50 and 60 hz

Hold the reset button for longer and the Power LED will flash different colours, release when it’s on the region you want: Green – EUR; Orange – USA; Red – JPN

(changing the region will also set the console to that regions default video mode)

Below is the basic stripboard that I put it on

It’s very easy to make, it’s just a small stripboard 8 holes wide, 8 holes tall.  Make the breaks that are shown in red and then solder the components on.  Oh, I forgot to include the ground point for the LED on the diagram, any spare hole on the top row will do.

All the components, stripboard ready

That’s all the components, I’ve already cut the stripboard to size and make the necessary breaks.  I found it easiest to solder the link first, then the socket, followed by the resistors then the capacitor (I soldered the capacitor at an angle in the end, slightly different to the diagram above but it still links the correct bits up!)

Link and socket in place

Underside just to confirm locations and breaks

Components in place

Using Sebs guide, and looking at my other Saturn guides (50/60hz and Region) should give you enough info on how to put this together.  My region guide also has some photos showing different motherboards JP locations/configuration.

The LED I used was a Red/Green one that I had removed from an old XBOX, but it should be easy to find a common cathode dual colour LED.  If you’re using then you’ll notice that the LED legs are already bent at a right angle, I shortened the legs and moved the bend a little bit, the following photo shows the correct colour wire going to the corresponding leg.

Red for Red, Black for GND, Green for Green!!!

Don’t forget you need to program the 16F630 PIC with sebs code.

I don’t usually use a PIC socket, but I did this time for a couple of reasons the first few times I did this.

  1. Just in case I had to reprogram the PIC
  2. I wasn’t sure how sensitive this PIC was, and didn’t want to damage it when soldering the legs

It’s up to you if you use a socket or not, as long as you don’t hold the soldering iron onto the legs too long, you should be fine not using a socket.

Here’s a photo showing a good place to mount the circuit board, I stuck the LED and the board down using double sided sticky foam (I’ve got an extra wire here, which is a 5v supply if I decide to fit a modchip later on).

If you’re modding a Model 1, or an early Model 2 with the separate board for the controller ports and reset button the you need to look at where the reset button connects.  On the one I did as a test the trace to cut was on the underside of the board.  The photo below shows where, the Yellow wire is the Button wire, the White wire is the Reset signal wire (the other end of the trace that needs to be cut).

Seperate board

Notes

Now that I’m more confident in programming PIC Chips in general, I don’t build the board anymore, I stick the chip to Saturn motherboard and solder straight onto the legs.

Finished installation with no board

Power?  you can get GND and +5v from many points on the board, or you can use the contacts from the PSU, or (like the photo above, use a multimeter to find points close to where you are fitting the chip).

+5v and Ground wires soldered

Switchless Mod Update with MultiBIOS by RetroRepair Show

 

Here’s some notes I made when working out how to adapt Sebs mod to work on other consoles,  you might find it useful if you plan to experiment with it.

This mod is designed to work with a Reset button that sends a GND signal off elsewhere else.  Leg 13 of the 16F30 PIC is waiting to receive the GND signal when you press the reset button, and looks at how you’ve pressed the Reset button (quick press, or a press and hold), it then (if necessary) alters the outputs (either +5v or GND) on legs 5 and 6 (the LED outputs), legs 8, 9 and 10 (the JP outputs) and leg 12 (video mode selection).  Remember, all of the outputs above are either +5v or GND.

If you just pressed the reset button quickly, or if you selected a different mode the PIC will always send out a GND signal on leg 11.  At all other times the PIC doesn’t send any signal out of leg 11.

You have to cut the trace coming out of the consoles Reset button contact points so that the PIC controls resetting the console.

If you plan on adapting this mod for another console, but it uses a Reset button that works with +5v signals instead of GND, then you have to invert the signal(s).  I’ve done this once for a Mega Drive (link to be updated once I’ve migrated the guides).

Be careful using the LED outputs for anything other than LEDs, remember that they blink when you switch the console on, change the video mode or select a new region.  For example, when you select 50hz video mode, the outputs of the LEDs switch between +5v and GND a couple of times to flash the LEDs.

Don’t forget that Leg 12 (which controls the Video mod on the Saturn) can be controlled independently of selecting the region by holding the Reset button for about 1 second.

Finally, here’s a table of the outputs for different modes

PIC Leg (and original Saturn function)
Region 5 (red LED) 6 (green LED) 8 (JP12) 9 (JP10) 10 (JP6) 12 (Vid Mode)
EUR GND +5v GND +5v +5v GND
JPN +5v GND +5v GND GND +5v
USA +5v +5v GND +5v GND +5v

Summary of Components

  • 1 x 16F630 PIC flashed with Sebs code
  • 1 x 14 pin socket for PIC (optional)
  • 1 x 100nF Ceramic Capacitor
  • 2 x 220 Ohm Resistors
  • 1 x Dual Colour LED (common cathode/negative)
  • Various Wire!