How to build a Sega Neptune

http://www.longhornengineer.com/DIY/Neptunehowto

Have fun modders!

:icon_bigg

 

Wow. Looks very neat actually. :nod: Would be awesome to have without that bulky tumor ontop of the Genesis! :lol:

 

this mod work for JVC Xeye Neptune

 

Maybe. Does the 32X work with JVC Xeye? If it does and there enough space you can do it.

 

It's hit or miss with the X'eye. In the standard configuration, the 32x blocks the CD drive door so it can't open. There's also some debate about whether or not the 32x reaches deep enough to get positive contact on all the cart slot connections. Theoretically an X'eye has all the same parts as a Genesis/Megadrive 2, so if there are missing connections or components a persistent modder could make the 32x work eventually.

 

Now all we've got to do is get some cases molded!

 

The Wondermegas / XEye lack the RGB sockets required to overlay the Megadrive graphics to the 32X as well as Sync. However it is possible, you just need...

RGB SCART converted Wondermega / XEye (not too hard to do GameSX has the details for this).

Reverse RGB lead (basically a SCART socket to Megadrive 1 or 2 RGB socket) so you can route the picture to the correct place (again GameSX has this information).

Cartridge port extender, those old Japanese Megadrive / Genesis or European Megadrive work well.

Foam cut roughly so the 32X can sit on top of this without wobbling on the cartridge port extender.

 

the 32x work for JVC Xeye I test and work

 

Xeye and wondermega have all required for 32x... all except enough space. Both are MD2+MCD in a same box, Wondermega also has a lot of extra stuff in it. Xeye could have 32x fit inside, as there's much more room in it that in Wondermega...

 

The Xeye as I found out does have a standard Megadrive 2 AV port... so will work with the 32X directly but the Sega / Victor Wondermega has a non standard AV port as well as phonos for Composite video and a S-Video port and the Victor Wondermega 2 only has the phono port for composite video and a s-video port.

Although the Xeye and Victor Wondermega 2 look similar they are very different....

 

Also, some very early revisions of the American X'eye don't have the built-in 9 mini pin AV port....I came across one. But I managed to install one too..I wrote a mod tutorial somewhere...

 

Wow, now thats impressive.

All he needs is to get a hold of that empty case thatz bouncing around prototype conventions and make a mold.

 

I really would like to do this mod or have a completed one. The Sega 32X is nice to have but it's very annoying how large it is and the RGB loop cable and separate power supply. I do find it interesting that the 850ma provided by the Genesis 2 AC adapter is enough for both systems. That makes it fit just perfectly to share power. I think it's much nicer to have to hookup a Genesis 2 + Sega CD since that is just two AC adapters and a AV cable. Rather than what I have now where I'd have a Genesis 1 with the mixing cable from the headphone out to the back of the CD system, the RGB loop cable, the actual AV cable, 3 AC adapters.... not to mention it being huge and tall.

 

oh lord that would take a bit of time

 

I've been thinking about building a Neptune using a MegaDrive 1 as it has more space and i find it nicer than the MD2. It doesn't look very difficult but obviously pretty time consuming. I also insist on using the MegaDrive cartride connector, so the cartridges doesn't stick up more, that won't make it any easier.

On Wikipedia it says that Master System converters won't work on the 32X.

"Also, Sega's Power Base Converter, which allows one to play Sega Master System games on a Mega Drive, could not be used with the 32X attached. This is because the Power Base Converter uses a specific grounding pin to tell the Mega Drive to enter Master System mode. The 32X itself does not pass through this pin to the Mega Drive, and therefore, the Mega Drive is unable to enter Master System mode with the 32X attached."

What pin would that be? If i use the MegaDrive cartridge connector for this it should be pretty easy to fix, but would it work?

I have lost my AV cable between the MD and 32X. What does the 32X use as sync, C. Sync or Composite Video?

Also i read somewhere a long time ago that saving in some MD games didn't work properly playing them through a 32X. Shining Force II was used as an example.
Is this true? I have the game and consoles but not the av cable so i can't test myself. Will someone test this claim (Shining Force II and 32X) and post their results?

Thanks.

 

I just remembered that the av connection cables aren't necessary to play MD games through the 32X, the normal MD out is sufficient. I put Shining Force II on and loaded an old save. Didn't have time to play until the next church so i unequipped the main characters weapon and saved the game. I switched off the console and loaded the save again and the weapon was still unequipped. Obviously this could be tested better but i'm fairly certain we can call BS on Shining Force II not being able to save through a 32X

So i put my Master System converter on the 32X and as expected that didn't work.
According to this site pin B10 and B30 needs to be grounded for the MD to go into SMS mode:
http://wiki.megadrive.org/index.php?title=Hardware:Interfaces

I opened up the 32X, SMS converter and a MD game to check if they used those pins. True enough the SMS converter had both those pins grounded and the MD game didn't use them at all.
The 32X on the other hand is a little weird. Pin B30 isn't connected to either Vcc or GND and as far as i can tell there is a clear passthrough to the 32X's cartridge connector. In other words this pin should work fine for SMS mode. B10 did as expected not have passthrough to B10 on the 32X cartridge connector. It does however seem to be connected to something, but the trace is lost under the SEGA 315-5818 chip. Does anyone know what the 32X uses this pin for? I was hoping that i could just connect the two B10's and that should make it go in SMS mode when the SMS converter is attached.

EDIT: The 32X cartridges doesn't use B10 and B30 either of course

 

I tried disconnecting B10 on the 32X end and grounded it instead. Which means both B10 and B30 were grounded at the same time which should make it go in SMS mode. However the 32X does need the B10 pin for some reason and it doesn't work, and not with MD cartrides either The only possibility left is to short the 32X's B10 with GND but i very much doubt that's a good idea

I guess i'll have to go through with this mod without SMS support :/

 

would be ultra-cool to get all 3 formats working in a single slot modded machine though

 

I won't be starting this mod for a month or so. There are a lot of things i need to buy before i can even begin. I'm fresh out of ideas for Master System support though. But i still hope we can make it work

 

couldn't you make a switch that bypasses the whole 32x board?