SNK Hyper NeoGeo 64 Arcade Hardware Stereo Sound Mod.

So as the title states this is just a quick and easy mod to enable direct output of Stereo Sound from the HNG64.

First up is Why? And the answer is, Because I can, I feel like it, and i like a nice easy way to hook it up to stereo speakers / external amp / whatever else i feel like. Or maybe adding this to an arcade cab with custom speakers etc..?

There are a few ways this could be done, but I'm doing it this way for a number of reasons,

1. I have the parts needed lying around.
2. It's nice and practical for what i need.
3. It's completely and Easily Reversible without damaging or altering the hardware.

What's required:

1. Good Quality wire that's not too thick but not too thin,
2. Some form of Stereo Audio Jacks or Sockets (3.5mm headphone jack or RCA phono jacks work nicely)
3. Solder
4. Soldering Iron

Now this could be done a little more easily if you had access to a connector that fits the 4 pin header on the HNG64 board, I initially tried a floppy drive molex power connector but it didn't fit even after trimming a little.

So what I decided to do is solder the wires directly to the pins from the header on the back of the PCB.

HNG64 Bottom PCB

The 4 pins are (from right to left when jamma connector is facing towards you) Audio Left, Ground, Audio right, Ground. The two ground pins are common and you can follow the traces from the other two pins for left and right audio to the corresponding pin on the JAMMA connector, they are clearly labelled on the HNG64, Pin L is for left audio or mono and Pin 10 is for right audio

Pins for Audio

I used some RCA phono jacks that i scavenged from an old satellite box a while back.

so all you need to do is connect 3 wires 1 for ground, 1 for Audio Right and one for Audio Left.

Then just hook up some speakers, receiver / amp or headphones and get your game on!

If you wanted to tap some un-amplfied audio you would need to get it from somewhere before the volume pot.

Volume can be controlled by the volume pot which is beside the 4 pin connector, also so this would be a great spot to put a headphone jack if you were to consolize the HNG64.

Some Interesting Arcade Hardware: HNG64

Got my hands on some interesting arcade hardware for a really good price on ebay, What I got were two systems in a bundle and then a game for them off the same seller(always handy to have a game...). One unit was meant to be working and the other faulty, which is fine as I like tinkering with these things. So what did I get?

What I did get is the Hyper Neo Geo 64 arcade system (HNG64) Fighting board and one game which is Fatal Fury: Wild Ambition / Garou Densetsu: wild ambition. As stated I got 2 of the arcade systems, one system is faulty and one works, so all good there. Now there's not a whole lot of information out there on the Hyper Neo Geo 64, or at least not easily found and accessible. It did not last very long when it was released and only has a handful of games(and you'd need very big hands to hold them).

Working board with game

Faulty Board, no game

Now with this hardware, there are a 4 different boards and different game types are only compatible with their specific board. the 4 types are: Fighting, Shooting, Driving and a Korean board, which only plays the Samurai Showdown games.

Having had some (all be it brief) experience with the older Neo Geo MVS hardware(progress with which is still on hold) I still had my hacked test control pad and MVS wired jamma harness, I just had to mod the latter slightly connecting up all the +5v Ground and +12v wires instead of just the top row as the HNG64 is a dual layer board. For video out I'm using RGB SCART so Red Green Blue and sync straight from the jamma harness.

There are 2 revisions of the HNG64, Rev1 is non JAMMA and Rev2 which has a JAMMA connector  which can be configured via a switch on the bottom PCB to either standard JAMMA or MVS mode, there is also a switch for the audio output which enables you to swap between Stereo/MVS and MONO jamma, as standard jamma only supports mono audio from the connector while MVS supports stereo.

SNK Hyper NeoGeo 64 MVS/JAMMA switches

Power: With Regards to Powering the HNG64 I am simply using a PC ATX power supply which gives plenty of amps on the +5v and 12v lines so Ground, +5v and +12v all come into the MVS JAMMA harness via a molex connector so it's nice and easy to connect / disconnect. the ATX power supply is modified with a simple switch to turn it on / off (as normally the PC motherboard would handle this) you can google how to do this if you want.

Sound: for Sound there is a 4 pin header near the JAMMA connector which is for Stereo out and also a Volume control which is nice. As I didn't have anything to plug into the header I had to do a small mod in order to use it. which I'll cover in another post.

Video Connection: Is just as stated earlier simple RGB and Sync taken directly from the JAMMA connector and going to RGB SCART, now not all TV sets or monitors will like this some are more tolerant than others, my Sony Trinitron works fine with this setup whereas my JVC CRT does display an image but it's not a very good one, this does work fine with a GBS 8220 CGA/EGA to VGA scaler/converter so with this it's nice and easy to hook it up to a VGA monitor, I have not tried any superguns but I assume the HNG64 should work fine with them although you may need to switch to jamma mode for some.

HNG64 on VGA monitor via GBS 8220 EGA/CVG to VGA converter board

Controls: for the controls ideally I'd want an arcade stick and buttons but sadly I do not have any, so going back to my MVS testing I took a MegaDrive ASCIIPAD which has a similar 4 button config to the neo geo and also a dpad, start, mode, and 2 shoulder buttons. I removed the chip in the controller and wired up the buttons to work with the jamma harness so the face buttons are ABCD and the Dpad is well.. The dpad up down left right, start is start, mode is 1p coin in, and the shoulder buttons I wired up for Test and Service.

Asciipad MD-6 hacked to work with MVS / JAMMA

Starting up: so with everything hooked up and the game rom board seated, it's time to fire this beast up, now what you will want to do is probably set some options in the test mode both for the game and the system, while there are some physical DIP switches on the board (a bank of 4) I have no idea what these do. instructions did come with the boards but they're all in Japanese, which I can't read. You will not be able to enter the test/service mode unless there is a game connected and loaded if no game is present then the system does not boot and sits at a blue screen, when powered up with a game in, it will run through some checks then display a crosshatch and boot the game you can then go into the test/service mode.

You can set various game and system options here all the usual like difficulty, credits, number of rounds etc and also I/O tests sound test and options and also set to Free play or whatever, one to watch out for is if you boot a game and there's no sound on the Hyper NeoGeo 64 animation or game intro, make sure you have "sound in demo mode" turned on.

The Faulty Board: as there seems to be little information on the hardware and no real reference or starting point for common faults it boils down to just simple fault finding, probing, testing, swapping parts, etc. trial and error basically all the fun stuff. 

What the board is doing now: It powers on but goes to a blank but stable red screen and stays this way. I believe the NeoGeo AES does something similar if there is a ram error, but I am unsure if this is in anyway related, perhaps the board is just dead altogether. 

What I know is working: Power, it's powering up and also the smaller bottom board as I have swapped this over with the working HNG64 and all is well so the issue lies with the top board which has some ram chips and the processors / whatever else is on there and also a large voltage regulator with a big heat sink. 

Where will I start: Well I will start to look at the ram as mentioned earlier the AES does something similar with ram faults and the ram checks are the first checks that the working board seems to perform power on / boot up.


Thoughts, Feelings and conclusion:

It's a step further into the unknown world of arcade hardware for me, and a journey I take on with wonder, awe and renewed optimism, As for the HNG64 I really like the thing, These are built like tanks, literally it even kinda looks like one with the game cart/rom board on top, very well made and heavy construction. 

There may not be a whole lot of games available and I may not be able to afford most of them but it's nice to have, and the game I do have is a lot of fun classic SNK fighting in 3D, Also this system puts out really nice crisp visuals and great audio. More to come on this. But I am very happy and will try to resurrect the faulty board if I can, if not then so be it.