Sega Neptune - Birth of the lost console

1/04/2008

The Sega Neptune was a combo 32x and Genesis console aimed at making the 32x add-on more successful. More information about the Sega Neptune can be found here. Breakpack over at Atariage.com commissioned me to build the second only working Sega Neptune. The first one was built some years ago here. Unfortunately, he did not take pictures of the insides of the console so I had to find my own means to get it to work. This mod set the benchmark of what my mod will have to accomplish.

[Heres an image of the first ever working Neptune. Not my image.]

[Insides of a Sega Genesis 2.]

[Insides of a Sega 32x add-on.]

To start I ripped and stripped the Genesis and 32x down to there circuit boards and tossed the RF shielding since there will be no room for it inside the Genesis case. The 32x has a great number of screws and is put together like a puzzle.

[The first test.]

Quick test yields that the system works without all the RF shielding. Take that FCC!

[Layout. Its going to be a tight one.]

To make it fit the 32x will need to stretch out and lay flat across the Genesis circuit board. There are some small capacitors that will need to be bent over to lower the height of the board.

[Rip them all down!]

And this shows just that. I just heated the contacts on the bottom and bent the cap over.

[Test two.]

Another test to make sure the caps still function. Now for the hard part.

[Look mom no cart slot!]

To connect the 32x to the Genesis I removed the cart slot on the Genesis then soldered wires from the cart slot contacts to the contacts on the 32x.

[First row.]

[Second row.]

The key here is to make sure the distance the wires have to travel is as short as possible with as few bends. I used 20AWG solid copper wire. I would not go any thinner then 20AWG as the signals could degrade.

[Soldering the second row to the 32x.]

[Soldering the first row to the 32x.]

[Close up on the first row.]

Notice how this row is soldered upside down. When the 32x is pushed against the Genesis board these wires will untwist and lay straight. This removed about 1/4" of wiring from the total length and kept the wires in a straight, unbent line.

[Testing to make sure the 64 wires are hooked up correctly.]

[The white ribbon cables.]

To reduce the height of the 32x, the rings on these white ribbon cables were smashed with a hammer and removed. The unit function without them.

[Genesis to 32x video cable.]

Then the 32x and Genesis where connected via 24AWG wire to replace the video cable connection. I soldered these connections on the solder side of the Genesis because I wanted to reuse video out hole on the original case.

Then I relocated the video out and power input on the 32x. I decided to use the two original power supplies because my budget did not allow the purchase of a new one that could power both units. If you want to use one power supply make sure to get a 10V power supply that can supply at least 2 amps.

[Hot glue saves the day!]

Mounting the video out. I removed the video out port on the Genesis and hot glued the video out on the 32x in its place. With the insides done I moved on to the case modifications.

Heres the cart slot. 32x carts are slightly larger then normal Genesis carts so some cutting with a xacto knife are necessary.

[The Genesis dust cover.]

The original dust cover mechanism was removed and replaced with the 32x dust covers.

[32x dust covers.]

Before the 32x dust covers could be installed some modifications had to be made. They have to be cut down to conserve space. I used a dremel with a cutting wheel to do it.

After a bit of hot glue the dust covers are in place.

[Installing the guts.]

I used #4 1" size wood screws that went through the 32x cart slot holes and into the original holes on the Genesis. The holes line up perfectly. However, I noticed that the dust covers hit the cart slot.

[Trimming the 32x cart slot.]

This was fixed by removing the RF shielding on the cart slot and cutting the cart slot down to size. Now the dust covers can open without hitting. Again, I used the dremel with a cutting wheel.

[Cover on and ready to go.]

A little video showing it in action.