My modded 3-4 AES.

Finally finished, had some luck, did some mistakes but fixed them.

BIG thanks goes to Jeff Kurtz who really went out on a limb to get me all the parts and also answer all my questions.
Many thanks goes to: Xian Xi, MKL and chaoticjelly for helping me with my questions.
Thanks also to Razoola and his awesome Unibios.


Ok, the Neo 3-4 AES now has: RGB, Composit, S-VHS, Component video out and stereo RCA, Digital Coax and Digital Toslink audio out.
It also has a power LED and a Reset button that lights up when pressed.


I wanted more separation between the audio and video connectors.
Note the small power led right next to the volume slider.


Here is the Reset button that lights up when pressed.
The button is grinded out and then a LED is grinded down and inserted, then the whole button is filled with hot glue.
I also bought some great new feet for the neo from Jamma-Nation X.


Unibios 3.0 is also installed with a socket.


Then I did the RGB bypass mod and the picture got alot better!
(I used 100 Ohms resistors cos 82 ohms was too bright for me.)


Drilling the holes and attaching the connectors.
It was a very tight fit with the Composite connector between the DIN and AC, I had to shorten it and bend the middle pin.


I installed Jeff Kurts Neobitz and a digital audio card.
(Note: Sync to RGB bypass was taken from pin 11 but sync to Neobitz was taken from Pin 10.)


The power LEDs power was taken from a nearby Capacitor and the reset button LED got +5v on the + (And a resistor on 100 Ohms.) and the - was connected to the reset buttons signal side.

Everything fit easily inside the Mighty Neo AES.




Some small adjustments were done here and there to fit the connectors and to secure the neobitz and audio cards inside the AES.
The hardest part was to fasten the Composit nut.

Everything works like a charm but I can see the edges "crawling" when in S-VHS and Composit.
Would a good guess be that a sync cleaner could fix that?


Ive seen people give names to their modded systems...so I will call mine....ehrm...MONO-modded! ...eh...hm...wait...

Was wondering if you could provide some details on the digital audio card and parts you used....

Been itching to do some digital audio out on mine as well.

Looks good!

Looks like you tapped the audio from the analog source. Was there not a way to input a digital source to the audio card?

Very interesting placement of the jacks I must say. Glad you are happy dude. What's next?

monouchi said:

Everything works like a charm

Click to expand...

Sorry but no, it doesn't. Revision 3-4 is affected by an audio problem consisting of a buzzing noise on both the A/V port and the headphone outputs. It's due to a stupid mistake done by SNK in an attempt to reduce the amount of components after the D/A conversion.

MKL said:

Sorry but no, it doesn't. Revision 3-4 is affected by an audio problem consisting of a buzzing noise on both the A/V port and the headphone outputs. It's due to a stupid mistake done by SNK in an attempt to reduce the amount of components after the D/A conversion.

Click to expand...

Good info MKL, no wonder the only "broken" AES I have is a 3-4 with an audio buzzing problem.

How do I fix it or go around it?

It can be fixed very easily. I've been wanting to post info about this for a long time but didn't have a 3-4 to take pics. Maybe you can take some closeups?

I'd love to but it's in storage where it's been for 3 years now...lol

Monouchi can you take pics of the sound section closeup? The area behind the controller ports between the red bridges on each side.

Xian Xi said:

I'd love to but it's in storage where it's been for 3 years now...lol

Monouchi can you take pics of the sound section closeup? The area behind the controller ports between the red bridges on each side.

Click to expand...

And maybe some details on the sound converter board

I do have some pics. They're not the best possible but I'll use them anyway. I'll make a thread about it tomorrow (its 2AM now here).

Thanks buddy, get some rest.

Xian Xi said:

Looks like you tapped the audio from the analog source. Was there not a way to input a digital source to the audio card?

Very interesting placement of the jacks I must say. Glad you are happy dude. What's next?

Click to expand...

Maybe there is, have to ask Jeff about that. And where do I get the digital audio from the neo pcb?

The next thing I want to fix is the "crawling" effect that can be seen in Composite and S-VHS (Sync cleaner?)
Jeff, do you have any input on this?

MKL said:

Sorry but no, it doesn't. Revision 3-4 is affected by an audio problem consisting of a buzzing noise on both the A/V port and the headphone outputs. It's due to a stupid mistake done by SNK in an attempt to reduce the amount of components after the D/A conversion.

Click to expand...

Hm, I plugged the neo RCA jacks and toslink into my Onkyo reciever and blasted away and I could not hear any buzzing noise?
I will have to test again.



xiao_haozi:
I got the converter board from Jeff, I dont know where he got it from though.

Ok, I did the sound test.

In normal play with quite high volume I could not hear any buzzing noise.
(Using the stereo sound from the headphone jack.)

On the silent tittle screen of AoF2 I could not hear any buzzing noise even when turning the sound on the TV to the max.

Then I connected a toslink cable to my Onkyo reciever, could not hear any buzzing noise when playing.
I then cranked the Onkyo up to max volume (80) and here I could hear a buzzing sound clearly.
(Though it could not be heard up to 60 and 40 is so high that the neighbours will hear.)



Xian and MKL, how does the buzzing noise appear for you?
(I will open up the Neo later and get some pics.)

Xian Xi said:

Looks like you tapped the audio from the analog source. Was there not a way to input a digital source to the audio card?

Click to expand...

Been looking into options for doing the optical out....
...so bumping James' question...
Is there a way/place to tap a digital source rather than doing an analog to digital conversion?

Depends on the audio card as well though if it can use a digital source input or is it stuck on analog.

Xian Xi said:

Depends on the audio card as well though if it can use a digital source input or is it stuck on analog.

Click to expand...

Yeah good point.

If you are just going with an analog to digital converter board ... can anyone attest to the quality of the sound output....

Im also curious of where to tap digital sound from the Neo pcb.

I do have tested the sound on mine and it was very hard to hear any buzzing sound as is said to exist on the 3-4.
(And yes, I also have worked a long time with good quality sound systems.)

If I maximized the volume the buzzing could be heard, but that is a little over the top imo.

For quality the digital sound was great, I even felt like it was better than the analog (more distinct bass) but maybe that was an sound illusion made by my high expectations.

Good job there. Like many here, always enjoy pics.

monouchi said:

Im also curious of where to tap digital sound from the Neo pcb.

I do have tested the sound on mine and it was very hard to hear any buzzing sound as is said to exist on the 3-4.
(And yes, I also have worked a long time with good quality sound systems.)

If I maximized the volume the buzzing could be heard, but that is a little over the top imo.

For quality the digital sound was great, I even felt like it was better than the analog (more distinct bass) but maybe that was an sound illusion made by my high expectations.

Click to expand...

Yeah would be great if there was a place to tap digital from the board.


As to the quality... glad to here you at least think it sounds better.
I was wondering if it was worth it above just having optical out as a novelty.
I figured it might sound a little better depending on what the converter is doing... like if there is any amplification in the circuit it could at least sound louder. I've always had to crank up my receiver and have wanted to put in a small amplifier on the lines.

That digital audio board sounds like a neat mod, do you know if it works with any other system?

electrochip said:

That digital audio board sounds like a neat mod, do you know if it works with any other system?

Click to expand...

It should since it's an analog to digital converter. It doesn't improve sound quality, it's more for convenience of the connection.

monouchi said:

The next thing I want to fix is the "crawling" effect that can be seen in Composite and S-VHS (Sync cleaner?)
Jeff, do you have any input on this?

Click to expand...

This is something I have been wondering myself.

Mostly asking the following questions to MKL and Jeff Kurtz:

My system is a 2nd model of the first design, I believe (serial #031084, I think it is 2nd model, it has the better looking daughter board). Even with the Neo Bitz, the composite and S-video has a little rainbowing with some dot crawl. It changes a little adjusting with the orange POT on the left of the system. I adjusted it so the component video is perfect and the S-video being the best possible. I don't use the Sync Cleaner due to it making the picture roll in component on any CRT. I had to use a 0.01uf cap on the sync line to get component to work right, but composite and s-video works with or without the cap. Pretty weird huh.

Is there anything else that could help stabilize the picture for all 3 connections?

Also, do I really need the cap on the sync line or is there something else that needs tweaking?

SNKNostalgia said:

My system is a 2nd model of the first design, I believe (serial #031084, I think it is 2nd model, it has the better looking daughter board). Even with the Neo Bitz, the composite and S-video has a little rainbowing with some dot crawl. It changes a little adjusting with the orange POT on the left of the system. I adjusted it so the component video is perfect and the S-video being the best possible.

Click to expand...

The pot is actually a variable capacitor and is part of the stock encoder circuit (it acts upon the crystal frequency). The neobitz is supposed to replace the stock encoder so that tweaking the trimmer cap shouldn't have any effect on the neobitz outputs. Unless the RGB inputs for the neobitz are the outputs of the stock encoder. If that's the case I suggest redoing the mod and getting rid of the stock encoder as well as the daughterboard, i.e. turning your system into a 1st gen NEO AES board model.

It would also be possible to have component from the neobitz (with trimmer cap having no effect on it) and composite/s-video from the stock encoder.

SNKNostalgia said:

I don't use the Sync Cleaner due to it making the picture roll in component on any CRT. I had to use a 0.01uf cap on the sync line to get component to work right, but composite and s-video works with or without the cap. Pretty weird huh.

Is there anything else that could help stabilize the picture for all 3 connections?

Also, do I really need the cap on the sync line or is there something else that needs tweaking?

Click to expand...

Have you ever tried if a MVS gives you the same issues? The sync goes through some extra components on MVS boards (see here)

Also, the sync voltage might be too high for the TV. Try reducing it with a voltage divider (even a variable one).

The RGB is tapped before the CXA inputs and resistors connected to it. I am using the resistors Jeff Kurtz included and suggested. The sync is connected to the input sync leg on the CXA. The signal comes in crappy if I use any sync outputs from it.

I do like the idea of removing the daughter board. I kinda had a feeling about removing the CXA was something I should have done while doing the mod in the first place. Weird how the variable cap changes the way the dot crawl and rainbowing/shimmering moves when it should just have to do with the CXA only.

So removing the daughter board won't hurt anything? I am assuming I need to take the crystal off it and put it where it originally would go on a 1st gen Neo Geo and that's it?

I don't have a MVS to mess with nor another AES Home System. I take it that the capacitor just delays the signal by holding back some of the power? Definitely will look into a voltage divider.

SNKNostalgia said:

I do like the idea of removing the daughter board. I kinda had a feeling about removing the CXA was something I should have done while doing the mod in the first place. Weird how the variable cap changes the way the dot crawl and rainbowing/shimmering moves when it should just have to do with the CXA only.

Click to expand...

I took a look at this and it's due to the fact that the trimmer cap is connected to the NTSC crystal input of the CXA encoder (pin 6) which in turn is connected to the main crystal on the daughterboard through a comparator (CXA23065). The daughterboard only has a purpose if the stock encoder is used. By removing the daughterboard the system will be identical to the earlier NEO-AES model and the MVS boards based on the same chipset (MV1, MV4, MV6) so the neobitz mod will be the same as if it were performed on these (which I don't know what it means in terms of dot crawling).

SNKNostalgia said:

So removing the daughter board won't hurt anything? I am assuming I need to take the crystal off it and put it where it originally would go on a 1st gen Neo Geo and that's it?

Click to expand...

Yes, although the crystal value on the very first AES model is 24MHz (as on MVS boards) while the crystal on the daughterboard is a little higher (24.16782MHz).