The audio issue of AES revision 3-4

**Green Beret** · 05-21-2014, 12:44 AM

If you have the volume of the speakers up, on Neo Geo logo you can hear a buzz and right after it where it says caution instructions for 1 sec the buzz changes to higher frequensy buzz for this sec, then it becomes the initial buzz sound.
I have put 4 104 caps and a 470uf on the sound chip. It didn't work.
But the 4 104 caps I used were larger in size (double size) compared to the caps MKL used. Maybe they were "Mylars" like Xian said. The shop had only them to give me.
EDIT Are mylars not suitable?

**HeavyMachineGun** · 05-21-2014, 12:59 AM

I didn't change out any Mylar caps. I thought those didn't usually have to be changed.

I haven't added the 3-4 fix either.

**Xian Xi** · 05-21-2014, 04:34 AM

They only need to be changed once in a great while. I don't think it's the mylars. Make sure you guys are putting the caps across VCC and ground pins on each chip and not just random pins.

**Green Beret** · 05-21-2014, 05:35 AM

Originally Posted by Xian Xi

They only need to be changed once in a great while. I don't think it's the mylars. Make sure you guys are putting the caps across VCC and ground pins on each chip and not just random pins.

Have you done it succesfully on a 3.3?

**Luciano** · 09-21-2015, 05:35 PM

Hi guys, I have a problem with my japanese 3-6 AES. It has a RGB bypass mod and stereo mod getting the signal from the Headphones. Unfortunately I am getting a buzz sound on my Hifi no matter how I connect it. I had another Neo Geo with a stereo mod before which did not have the problem.

I used good shielded cables and the mod is correctly done. Is there any solution?

**Xian Xi** · 09-21-2015, 06:40 PM

Who made the cable?

**donluca** · 09-22-2015, 06:35 AM

Originally Posted by Luciano

Hi guys, I have a problem with my japanese 3-6 AES. It has a RGB bypass mod and stereo mod getting the signal from the Headphones. Unfortunately I am getting a buzz sound on my Hifi no matter how I connect it. I had another Neo Geo with a stereo mod before which did not have the problem.

I used good shielded cables and the mod is correctly done. Is there any solution?

The audio signal is likely to be missing ground. Just connect it from the neo geo to the RCA cables (or whatever you're using), you can get it from a lot of places.

**Luciano** · 09-22-2015, 06:52 AM

The cable was made by a friend of mine and he also made the cable I had with the other Neo which did not have the buzzing. Cable should be fine, he knows what he does.

I took the ground signal close to the audio L and Audio R, should I take it somewhere else? Its going through scart.

**donluca** · 09-22-2015, 08:24 AM

Check in your scart if the audio ground is wired properly. It should be pin 4.

**Luciano** · 09-22-2015, 12:49 PM

There is ground, but only connected from the main ground. Is this the problem?

**donluca** · 09-22-2015, 01:56 PM

Originally Posted by Luciano

There is ground, but only connected from the main ground. Is this the problem?

To do stuff properly, ALL grounds should be connected.

For now, if video works ok, just solder a wire going from the ground pin to the audio ground pin (which is pin 4 - refer to the above picture).

**Luciano** · 09-22-2015, 02:59 PM

As I said before, there is a ground connected to pin 4, but its coming from pin 18.

**donluca** · 09-22-2015, 03:25 PM

If you've already checked with a multimeter if there's continuity between pin 4, RCA Ground and a ground point on the board, there's definitely no ground issues and we can move forward.
Although buzzing sounds are 99% of times related to a missing ground connection.

One more thing: do you have all the power supplies plugged into the same power strip?

I remember once I was getting crazy because I had a loud buzz in the sound and couldn't understand where that came from. Ultimately I discovered I had a ground loop and solved by plugging all the power supplies in the chain to the same power strip.

**Luciano** · 09-24-2015, 10:19 AM

I will try, thank you!

**Fakk2** · 11-24-2015, 06:18 PM

All the pics of the first post appear to be dead links. Can someone please replace them here if they have them? I would appreciate it.

**DaytimeDreamer** · 02-14-2016, 03:40 PM

Originally Posted by Fakk2

All the pics of the first post appear to be dead links. Can someone please replace them here if they have them? I would appreciate it.

Basically this. I need to send an AES 3-4 for fixing and it would be great if we could find some pics related to the first post.

**nam9** · 03-03-2016, 09:38 AM

Damn, when did these go down? I just picked up a bag of bypass caps...
Does anyone have the pic showing the blue bypass caps on the underside of the motherboard?

Edit: Found it...

3-4 Ceramic caps.jpg

**PIXeL_92** · 10-01-2016, 04:33 PM

I am trying to resolve the issue on my 3-6 board but the pictures are no longer valid, did anyone save a copy of them ? Cheers

**YodaChips** · 10-09-2016, 11:43 AM

Where did you find it??
Thx

Originally Posted by nam9

Damn, when did these go down? I just picked up a bag of bypass caps...
Does anyone have the pic showing the blue bypass caps on the underside of the motherboard?

Edit: Found it...

3-4 Ceramic caps.jpg

**DaytimeDreamer** · 12-20-2016, 06:19 PM

If anyone has done the ceramic cap mod can he upload a high resolution pic so we can see this better?

**DaytimeDreamer** · 04-12-2017, 04:53 AM

Bumping this thread.

Since all pics of the original post by MKL are lost you can use this thread here for reference. Expect detailed pics of the mod is some days when I receive the 3-4 board back

http://www.neo-geo.com/forums/showth...Video-Audio%29

Thread: The audio issue of AES revision 3-4

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