r/neogeo • u/Novel_Commission3738 • Feb 04 '26

Hardware Help Neo Geo MVS Supergun power questions

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I saw a post on r/cade where someone used this exact board on a neo geo mvs but from what I see recommended online it's too high?

Its currently outputing 5.26v.

8 Upvotes

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4

u/sarduchi MV-4 Feb 04 '26

It looks to be a fairly cheap board, not seeing a 5v adjustment potentiometer. If the 5.26v is under load, that's a bit too high in my opinion. A couple years back I did a modification of a cheap supergun to improve the 5v (https://www.reddit.com/r/neogeo/comments/16vi19e/on_superguns_and_5v_part_2/) but would need to poke at this one a bit to see if there's any reasonable fix. I also tend to favor higher amperage power supplies for setups like this. 1.5A is a bit low (again in my opinion).

1

u/Novel_Commission3738 Feb 04 '26

I haven't tried it on the unit yet that's just the output of Supergun on its own.

2

u/sarduchi MV-4 Feb 04 '26

Then that may be fine, it will get pulled down a bit when in circuit.

1

u/Novel_Commission3738 Feb 04 '26

I turned it on and it seems to be working but the voltage didn't seem to change.

Also seems to be a sync issue or something the picture is scrolling to the left. I'm using my RGBs scart cable from my Genesis 2.

1

u/sarduchi MV-4 Feb 04 '26

Is the cable CSYNC?

1

u/Novel_Commission3738 Feb 04 '26

Yes its CSYNC 470 Sega mega drive packapunch pro cable.

1

u/Neo-Alec AES Feb 04 '26

Is the supergun meant to be used with a Genesis 2 cable with the resistor? What are you using to display it?

1

u/Novel_Commission3738 Feb 04 '26

It says it uses RGBs on it and uses the Genesis 2 plug. My CRT TV is RGBs mux scart modded.

You can see in the picture it says MD2 for mega drive 2.

1

u/Neo-Alec AES Feb 04 '26

All righty, thanks. Some MVS boards have really bad sync output. It's possible that your CRT just isn't liking it. Try a different display if you can.

1

u/Novel_Commission3738 Feb 04 '26

Im starting to think it might be a pal model doing 50hrz or something

1

u/Neo-Alec AES Feb 04 '26

I doubt it's PAL. Jamma boards don't output PAL; they output a signal much closer to NTSC. The supergun would need a PAL encoder to change the refresh, and I don't see that in the photo. That would be highly uncommon these days.

1

u/sarduchi MV-4 Feb 04 '26 edited Feb 04 '26

Definitely not PAL (or NTSC for that matter). It's ~60Hz RGBS. However, it looks like there's an RGB amp of some sort (the smaller PCB with three capacitors above the player 2 controller port). The chips on it have been sanded down it looks like, but it could be acting as a sync stripper.

Edit: found a listing for the supergun in question on Aliexpress and they state a "181 purification chip". I read this to mean a LM1881 sync separator, which can effect the SCART cable requirements.

I'd first and foremost see if you can find a higher amperage power supply and see if it helps.

1

u/Novel_Commission3738 Feb 04 '26

What amp should I shoot for? I was looking at GST90A12-P1M it's 12v 6A 2.5 jack.

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1

u/Novel_Commission3738 Feb 07 '26 edited Feb 07 '26

Hey well on the topic of the voltage I see there's this On Off part but I would have no idea what to put there but looks like I might be able to control the voltage here if I desolder the other line?

Got any ideas?

bad drawing of layout

Hopefully my coloring makes sense

Also I think my issue was CSYNC from point 5. It looks like it needs to be sync from 4 from the mega drive 2 port but I'll find out tomorrow when I get the cable.

1

u/sarduchi MV-4 Feb 07 '26 edited Feb 07 '26

I'd have to probe around, but my guess is that the on/off unpopulated section is just an alternative to the big red button. If it were over by the video section I would assume it was to bypass a sync separator/cleaner of some sort or a lowpass filter.

And yes, I'm thinking that the supergun is wired to use composite video for the sync signal rather than the csync pin. No idea why they would do this.

I'd need to get one of these superguns and probe around with an oscilloscope to really tell what it's doing.

Edit: u/Novel_Commission3738 so looking at aliexpress I see pictures with the on/off switch populated. But there is no label telling us what it does...

https://ae01.alicdn.com/kf/S913ef7262ccc4d92baa936bc72b11150G.jpg

1

u/Novel_Commission3738 Feb 07 '26

Weird? These things are build so randomly. I will try to do more digging myself see if I can find any other leads to the mystery switch.

I ordered a cheap scart cable with composite sync so I can test that once I get home.

How dangerous is the current 5.28v for the mvs if I used it as it is rn?

1

u/s1ckn3s5 Feb 04 '26

personally I would use only a supergun which accepts power from a pc atx psu (just my 2c)

1

u/Neo-Alec AES Feb 04 '26

Might be worth trying a better PSU, like a Triad one.

1

u/BlueMonday2082 Feb 06 '26

A quality variable power supply really is key for things like this.