Inside a Chihiro (Xbox arcade unit)

**Parris** · 08-19-2009

Last night I was putting a Chihiro system out on placement. I'd previously had no time to have a look at the internals as I knew they worked perfectly.

So, as the tail gate van got caught in traffic before it arrived, I decided to use the 10 or 15mins to gut a Chihiro for the first time.

Anyone familiar with the arcade unit will know that it's actually a firmware updated Xbox Debug motherboard attached to a couple of custom PCBs.

However, it's a very expensive Xbox unit! Sorry if some of the images are a bit blurry, but I didn't have much time and the lighting was awful.

The motherboard is 128Mb, but the DIMM board (which is where the GDrom gets stored is 512Mb - standard memory)
The casing is made of metal and plastic. The side L legs are plastic, but the rest of the case is solid metal.

The Sega I/O which is attached to the unique PCB.

On the side of the Chihiro are the rest of the connections. Note the standard Xbox AV and LAN connections
Above are the Chihiro connections attached to the same unique PCB that the Sega I/O is attached to.

A rather clumsy way to handle the AV out from the main motherboard, goes to a unique connector attached to the PCB above. The signal then outputs via VGA. The USB port is actually JVS I/O for the control panel (in this case guns).

GDrom DIMM connector. This is the second unique PCB.

This is the top of the main unique PCB - look at 2 images down and you'll see the flip side.

Anyone recognize the Xbox debug motherboard?

That unique Sega PCB which handles outputs.

The Chihiro splash screen. It takes a very long time to boot and is very similar to the Tri Force boot process.

**l_oliveira** · 08-19-2009

Sadly the picture of the mainboard does not have the MCPX (southbridge) chip visible. Because the SEGA board is hooked to the mainboard LCP bus (debug port) it does not need to be a debug board, but it could be a normal retail board with a custom ROM and all ram positions populated. A custom bios is enough to make a retail board work with 128MB ram.

The only real difference from a devkit board to a retail board is the MCPX chip internal boot ROM. :)
The rest is identical (besides the retail having only 64MB of ram on it's original configuration)

Thanks for the pictures. I wish there were a picture of the MCPX chip on the XBOX mainboard but don't worry about that.
I guess it's enough trouble to disassembly it once.

**Parris** · 08-19-2009

Originally Posted by l_oliveira

Sadly the picture of the mainboard does not have the MCPX (southbridge) chip visible. Because the SEGA board is hooked to the mainboard LCP bus (debug port) it does not need to be a debug board, but it could be a normal retail board with a custom ROM and all ram positions populated. A custom bios is enough to make a retail board work with 128MB ram.

The only real difference from a devkit board to a retail board is the MCPX chip internal boot ROM. :)
The rest is identical (besides the retail having only 64MB of ram on it's original configuration)

Thanks for the pictures. I wish there were a picture of the MCPX chip on the XBOX mainboard but don't worry about that.
I guess it's enough trouble to disassembly it once.

What I meant was that it was a debug motherboard, but clearly you can establish that a custom retail board would probably also do the trick. MS would have supplied debug motherboards however, which really is the fastest route.

I literally I had 10 mins to take it apart and put it back together again. The only chance I shall have to take further images is when it comes back off hire in several months.

**Pikkon** · 08-20-2009

Thanks for the pics Gavin,I had no idea about the xbox debug motherboards.

**Storm** · 08-20-2009

Thanks for the Pictures Parris. I didn't know they used the GDrom packages.

**Barc0de** · 08-20-2009

Cheers mate, always wanted to see one of those naked=)

**SuperGrafx** · 09-01-2009

Pretty interesting pics.
The arcade near my city has a couple of Chihiro cabs (Ghost Squad and Maximum Tune)...always wondered just how similar the Chihiro really was to a stock Xbox console internally.

**Jamtex** · 09-01-2009

That does look like the laziest piece of arcade hardware I've ever seen, even the newest (and soon to be little used, hello Triforce...) Capcom Wii based hardware is a custom board.

Still thanks for opening it up and showing it to us unworthy people :)

**Parris** · 09-02-2009

Originally Posted by Jamtex

That does look like the laziest piece of arcade hardware I've ever seen, even the newest (and soon to be little used, hello Triforce...) Capcom Wii based hardware is a custom board.

Still thanks for opening it up and showing it to us unworthy people :)

Ah, yes, however it does mean that obtaining a spare / replacement motherboard is pretty straight forward for people who know their development hardware ;-) It's a far cheaper route to purchase a £70-80 Debug kit and flash it, than go to Sega and spend several hundred quid for the same thing!

You are more than welcome. Just please it didn't disappear with MS boards being pulled!

The Chihiro came back this week with a strange I/O fault not related to the motherboard, so I may be able to take better images and will post them here.

I've got images of a few arcade motherboards and you'd be surprised (or perhaps not) how familiar some of them are.

Last year I sold (stupidly, now I want it back) my System 245 motherboard based on the PS2. Opened it up before selling it and lo, it was an early revision PS2 motherboard, connected to custom Namco PCBs. However the motherboard still had the standard PS2 outputs, including optical out. Guess what, not disabled! So, I could get digital I/O from the 245 whilst all arcades were running via RCA.

**Parris** · 02-18-2010

Right, I have the Chihiro here for a few days before it goes off on its travels again and decided to take better external images of the unit.

It's attached to a standard Sega Naomi GDrom. As far as I am aware no cart software was ever produced for the Chihiro, it was all GDrom.

This unit is Region USA V1. Later versions were larger and had the DIMM internally, plus dropped the rather cumbersome and awkward (badly designed is what I am trying to say), hook up from main motherboard to daughter board via a custom external Xbox cable!

As the hook ups and I/O are Sega standard and JVS you could use a Chihiro in a Naomi cabinet with the correct control panel attached (depending upon the games title). For example the V1 unit will happily go into an Initial D cabinet and run. You'd be able to replace Initial D for Outrun 2 for example, however according to those in the know the gear ratio for the steering column is wrong and it makes driving almost impossible. You have to source either an OR2 dashboard or a Scud Racer dash.

Chihiro motherboards are really hard to obtain and relatively expensive. They are one of the most expensive Xbox units you'll see!

**Matthijscoman** · 02-18-2010

Great to see some more pictures of a Chihiro! I'd love to pick one up, but the limited amount of games which all need a dedicated cab and the high price makes it a no-go for me.

And you can't run every game on a Revision 1 board, can you?

Originally Posted by Parris

You'd be able to replace Initial D for Outrun 2 for example, however according to those in the know the gear ratio for the steering column is wrong and it makes driving almost impossible. You have to source either an OR2 dashboard or a Scud Racer dash.

Any chance you know how compatible an ID cab is with the other Naomi 2/Triforce/Chihiro driving games? For example, would you be able to drop in F-Zero AX without a control panel swap?

**Parris** · 02-19-2010

Originally Posted by Matthijscoman

Great to see some more pictures of a Chihiro! I'd love to pick one up, but the limited amount of games which all need a dedicated cab and the high price makes it a no-go for me.

And you can't run every game on a Revision 1 board, can you?

Any chance you know how compatible an ID cab is with the other Naomi 2/Triforce/Chihiro driving games? For example, would you be able to drop in F-Zero AX without a control panel swap?

A Chihiro motherboard is worth somewhere in the region of £500-600 currently, but remain really hard to find due to the fact they are mainly running titles people like and are still pulling in cash at arcades.

Give it about 2 or 3 years and they'll drop in value, but I still can't see them flooding the market.

No, there are very few games titles that will run on Rev 1. If I wanted to upgrade to OR2 SP for example, I would need to change the motherboard completely, so it's unlike the Naomi in that respect. If you buy a Naomi 1 then you have a large array of titles available to you, but the Naomi 2 is limited to only a few (such as Initial D). The Naomi 2 is roughly 3 times the cost of the Naomi 1 at present and is reputed to run all Naomi 1 titles (so you could argue that it's better to use N2 boards), but they are more fragile (often turning up as spares / repair on eBay) and I've found a number of N1 titles that fail to boot.

I really don't know about F-Zero AX and whether you'd need a different control panel. The ID cab uses 2 servo motors / a belt drive for forcefeed back and has a different wiring loom and gearing ratio to older Naomi titles and I suspect it would be the same with Tri Force.

Best contact Andy Geezer for more accurate information, although I am not sure he has had much dealings with Tri Force.

It would be good for one of the sites to list the various genuine cabinets and confirm the software that runs, or will run, but be problematic.