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Neo Geo 1X Stereo Mod

Sp33dFr34k

Sp33dFr34k

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So, I have a MV-1FZ and thought about stereo modding it. I came across this website which posted a SMD version of the PCB as designed by MKL. Ordered a few including parts and soldered it up.

Clean PCB versus fully soldered up and ready to go.



Because it's SMD it's very low-profile and easy to tuck away inside the already pretty compact 1FZ motherboard.



As per above website there are more alternatives regarding the points you can connect your PCB to on the motherboard but I decided to go for the bottom.

In the end it looks like this, plug & play so the 4-pin header goes straight into the audio amp of my NAC (NVS4000).



There was a minimum order quantity so I have a couple left, will probably be offering them later in the for sale section should somebody be interested :)

Special thanks to my buddy @PascalP for lending me his equipment :thumbsup:
 
It's a lot of dedication, but after I converted my 2-slot cab from Mono to stereo I'll never look back and I can see why you did this. The neo really deserves it. Good job and enjoy!
 
skate323k137 said:
It's a lot of dedication, but after I converted my 2-slot cab from Mono to stereo I'll never look back and I can see why you did this. The neo really deserves it. Good job and enjoy!
Click to expand...
Thanks, I did find some sites going over the schematic which involved making your own breadbord, but I didn't like that solution too much, so decided to go for this one. A lot cleaner looking and more compact. Don't have a hot air station (yet) though, so that's where Pascal's gear came in handy :thumbup:

All in all it's a pretty simple and straightforward mod which I'd recommend to everyone as well. I was planning on keeping my 1F, but now my 1FZ has been fully recapped, stereo modded, battery modded ánd being half the size... it might be the one staying rather than the 1F... :rolleyes:
 
Nice work! I've done the regular stereo mod to my MV-1C (disabling the mono circuit and drawing stereo from the IC). Would this be a big improvement over that method?
 
SmokeMonster said:
Nice work! I've done the regular stereo mod to my MV-1C (disabling the mono circuit and drawing stereo from the IC). Would this be a big improvement over that method?
Click to expand...
It should be basically the same, I believe all stereo mods out there are based on MKL's schematic, this one's just a way of having it sitting neatly on a PCB :)
Wombat said:
Really cool and neat solution!
Will this solution perhaps also work with a MV-1A?
Click to expand...
Yes, the website I linked to mentions these MVS revisions: MV-1A, MV-1AX, MV-1C, MV-1FZ, MV-1FZS, MV-1T. Basically all boards which don't output stereo by default actually have a stereo circuit onboard, it's just joined together to create dual mono, which this mod undoes basically :)
 
This prompted me to finally get round to doing the stereo mod. I missed out on getting one of the PCBs above, so I dug out the breadboard and bits that I got a while back.

I'd definitely recommend it - the stereo output really does make a difference on all the games I've played thus far 8)
 
I just assembled and installed one of these stereo amps in my MV-1FZ. Very satisfied at how compact it is.

3187CAFF-99AD-4CD6-981D-2814B94A2E0E.jpeg
F0DCA5C1-8061-489B-8615-54ED7C1B6872.jpeg
 
Nice and compact, for wiring purposes, I’d move VCC and GND to the input side. You can grab VCC and GND from the ICs right next to the inputs and the analog channel from the 4.7uf cap for the mix. That way all the wiring stays under the PCB and only the two outputs are the only wires coming out.
 
XianXi said:
Nice and compact, for wiring purposes, I’d move VCC and GND to the input side. You can grab VCC and GND from the ICs right next to the inputs and the analog channel from the 4.7uf cap for the mix. That way all the wiring stays under the PCB and only the two outputs are the only wires coming out.
Click to expand...
True, I still need to rewire mine to RCA jacks and was planning to use the VCC and GND points on the bottom :)
 
Hi
On the advice of XianXI, I would like to install this stereo mod in my MV-1b board.

There is not a lot of infos for this specific MVS.
I think I can grab +5v and ground on the bottom left of the board, but I don't know if I need to cut any traces or remove any resistors. Any ideas ? Also, does it remove the jamma mono output ?

Thanks
 
The MV-1B has the same ICs as the MV-1FZ(S) - "C844G" as OP AMP and the "YM2610" as sound synthesis and playback chip.

Therefore I would assume that the work steps for the amplified stereo mod would be the same, too.
  • YM2610 pin #27 (analog out) as "Mix"
  • trace pins #8 and #14 of the C844G --> find the related resistors and remove them --> take the pins as left (#8) and right (#14)
 
SmokeMonster said:
Nice work! I've done the regular stereo mod to my MV-1C (disabling the mono circuit and drawing stereo from the IC). Would this be a big improvement over that method?
Click to expand...
Sorry for gravedigging an old thread, but I've been recently doing some work on MV-1Cs and came across this.

So, here is the schematic for this "1X stereo mod":

stereoj.jpg


The MV-1C Ch1/Ch2 pins are sourced from the D/A chip which already includes the "Ch3" (mix) channel, so the left side of the circuit (channel mixing) is not applicable to it.

The D/A chip however does not include any kind of amplification, which means it can't drive anything without losing amplitude - audio transformers, headphones, long cables etc.

I have not yet built the above circuit since I only just found it, but I did build an equivalent buffer using NE5532 opamp and it works fine.

So to answer your question: Unless you're experiencing problems with low volume from MV-1C, there isn't any immediate benefit from the added amp circuit. You'd only be pre-emptively solving any such potential problems in the future. Same applies to all other MVS boards with stereo mod already done.
 
I'm digging this up again too! I suspect my C844G or YM3016-D died after recapping as I lost audio. Can someone recommend a quad op amp to replace the C844G? I don't know of a way to verify what died, so I'll just have to replace and see. I tried shorting channel 1 and channel 2 on the TM3016-D to an bluetooth speaker but I got nothing.
 
Use a logic probe w/audio and you can literally track it down to where it stops. If a game is playing while testing, when you probe, you can hear the audio with it.
 
XianXi said:
Yup, looks like it
Click to expand...

The probe arrived. I tested the op amp's output on pin 8 and 14, I got a steady high if I set the probe to TTL mode. On board connector A50 for tapping C, I got a steady low. To test if I can actually hear the music from this probe, I tested it out on a known good sound source (Dreamcast at the scart cable output) and I got a steady low on both L and R audio pins... Not sure what this means. I also probed the YM3016-D pin 10 and 11, also steady high. I think I'm supposed to see pulses?

One other thing I saw was, the stereo mod direction on your JNX picture says to tap A from pin 8 and 9, which are indeed shorted in the trace, but for pin 13 and 14, they are not shorted. I only tapped A from pin 14 since that's actual op amp's output. Most posts I see mention pin 13 and 14 are shorted on the trace, but not so on mine.

I realize this is straying far off topic of the original post, I can post somewhere else if this is not appropriate.
 
Going further upstream, pin 4 of the YM3016-D gave a steady pulsing beeps. If I run the sound test without a cart, with sound off or on any channel, it makes no difference in the pulse. So that's supposed to mean the YM2610 is bad based on a video from Arcadecomponents.com youtube channel. That's weird because I didn't touch that chip when I recapped.

Testing the serial data output on the YM2610 pin 31, I hear the same steady pulse beep as pin 4 of YM3016-D regardless of the sound on or off from the sound test. I also tested the clock pins on both YM chips, and there's pulses. Also pushed on the YM2610 while the sound is turned on to see if it's a bad joint, no change. Can someone interpret these results for me? Is it a bad YM2610?

Something to add, right after I did the JNX stereo mod, before recapping, I was getting lower left channel volume compared to the right. Not sure if it's a sign the 2610 was going bad. The sound test is also from Unibios 4.0, so none of these test might be relevant?
 
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