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Thread: Neo Geo AES 3-4 revision: Mods and enhancements (Video/Audio)

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    icon26.gif Neo Geo AES 3-4 revision: Mods and enhancements (Video/Audio)

    I opened up a thread regarding the Neo Geo AES 3-3 board revision here but thought to start a new thread since MKL's thread about fixing the audio issues has no images anymore so this new thread will serve as a information / advice thread and pic repository with before and after pics once the mods get done.

    Here is the stock AES 3-4 board









    Question to Xian Xi since he provided most of the information on the 3-3 board which looks pretty much identical to this one:

    Do the same 3-3 mods apply for the 3-4 board? Here is a list of the 3-3 mods Xian stated:

    - To fix the audio, you just need to add a cap to the headphone amp and add bypass caps on the 4558s. For the headphone amp, 470uf/220uf and got bypass caps they are always 0.1uf. (for the bypass you can use ceramic dipped) All caps would be connected between power and ground. + to vcc and - to vdd.

    - To fix the weak rgb, you can try altering the voltage divider on the rgb lines. You'll see 6.8k tied to iirc 2.2k resistors. Remove the 2.2ks and replace them with 2.6-2.8k resistors. Voltage at least 6.3v, (10v is a good choice)

    Any input/help on the above appreciated.
    Last edited by DaytimeDreamer; 12-20-2016 at 06:02 PM.

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    I have a 3-4 revision , at first i've done an rgb fix (replacing caps and some resistors ) : the picture was better but i finally done an rgb bypass , and the picture was soo much better , in fact just perfect ....

    In my opinion ,if you don't care about composite signal and want the best rgb output , bypassing the Sony CXA chip is the solution .

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    Quote Originally Posted by greatfunky View Post
    I have a 3-4 revision , at first i've done an rgb fix (replacing caps and some resistors ) : the picture was better but i finally done an rgb bypass , and the picture was soo much better , in fact just perfect ....

    In my opinion ,if you don't care about composite signal and want the best rgb output , bypassing the Sony CXA chip is the solution .
    Thanks for the reply. So since this is an infromation collecting post basically here are some questions:

    1) Which caps and resistors do you need to replace on a 3-4 system? The ones stated above just like a 3-3 system?
    2) How do you do an RGB bypass in a 3-4 system? What needs to be done?

    Thanks

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    Quote Originally Posted by DaytimeDreamer View Post
    Thanks for the reply. So since this is an infromation collecting post basically here are some questions:

    1) Which caps and resistors do you need to replace on a 3-4 system? The ones stated above just like a 3-3 system?
    2) How do you do an RGB bypass in a 3-4 system? What needs to be done?

    Thanks
    ok , so ...

    1) Using the recommended caps/resistors by sony on the CXA chip rgb output , like in 3-5 , 3-6 revisions : 470uf caps with 75 ohm resistors instead of the 100uf caps with 68 ohm resistors.

    2) For the bypass, removing the four caps (same as stated above) and the three 6.8k resistors like in the picture.

    04.jpg

    Then, soldering 4 wires , but without resistance , the picture may be a bit too bright so you could add 82 , 100 or 120ohm on the RGB lines to adjust the picture ( depending of your TV , my sony crt run fine with 120 ohm ).

    03.jpg
    Last edited by greatfunky; 12-20-2016 at 12:11 PM.

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    Thanks greatfunky. Noted down, good info

    Now for some feedback on the audio mods on this board. Xian Xin had recommended the following for a 3-3 board:

    - To fix the audio, you just need to add a cap to the headphone amp and add bypass caps on the 4558s. For the headphone amp, 470uf/220uf and got bypass caps they are always 0.1uf. (for the bypass you can use ceramic dipped) All caps would be connected between power and ground. + to vcc and - to vdd.

    Questions regarding a 3-4 board:

    Does the above still apply? If yes where exactly do you add the cap to the headphone amp? Can someone illustrate this using the pics in the first post of this thread? The bypass caps I guess are soldered on the other side of the board right?

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    You actually don't need to remove the 6.8k resistors to do the bypass but you can if you want to completely cut off the CXA1145.

    As for the audio, 3-3 and 3-4 should be pretty much the same.

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    Quote Originally Posted by Xian Xi View Post
    You actually don't need to remove the 6.8k resistors to do the bypass but you can if you want to completely cut off the CXA1145.

    As for the audio, 3-3 and 3-4 should be pretty much the same.
    Thanks James. Is it better to completely cut off the CXA1145 for RGB?

    The headphone amp is the JRC 2066D preamp? Where exactly does the 470uf/220uf cap need to be connected? Can you illustrate this on the fourth (last) pic in the first post please?

    Also asked this in MKL's thread concerning the 3-4 sound issues but asking here again. If anyone has a higher resolution pic with the ceramic bypass caps added on the 4558s please upload one.

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    Quote Originally Posted by DaytimeDreamer View Post
    Thanks James. Is it better to completely cut off the CXA1145 for RGB?

    The headphone amp is the JRC 2066D preamp? Where exactly does the 470uf/220uf cap need to be connected? Can you illustrate this on the fourth (last) pic in the first post please?

    Also asked this in MKL's thread concerning the 3-4 sound issues but asking here again. If anyone has a higher resolution pic with the ceramic bypass caps added on the 4558s please upload one.
    On all sound ICs it goes to power and ground. I think on the 2066D it's the first and last pin. You would need to check the datasheet to see which is which, same with the 4558s.

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    Quote Originally Posted by Xian Xi View Post
    On all sound ICs it goes to power and ground. I think on the 2066D it's the first and last pin. You would need to check the datasheet to see which is which, same with the 4558s.
    Thanks James. Now I have pretty much all the information needed. I'll take detailed photos of everything before and after the mods and some videos with the picture quality. I'll test these on a B&O MX4002

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    Just a head's up this 3-4 board is being fitted with new capacitors, audio fix and also having the RGB bypass fix to it.

    I'll post close-ups of the 3-4 board and some screens of the RGB quality once I get it back.

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    Looking forward to the outcome...duder

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    Quote Originally Posted by DaytimeDreamer View Post
    Just a head's up this 3-4 board is being fitted with new capacitors, audio fix and also having the RGB bypass fix to it.

    I'll post close-ups of the 3-4 board and some screens of the RGB quality once I get it back.
    Quote Originally Posted by Flagshiphero View Post
    Looking forward to the outcome...duder
    He's back! Are you still into Neo duder?! I'll catch up with you properly. Expect a PM on Facebook shortly

    Now let's list the fixes one by one. These are the pics I received from the guy which is fixing this Neo Geo AES 3-4 from me. Once I get it back I'll replace this pics with some hi-res ones. Hope this thread will serve as reference to many members in the future:

    1) RGB fix and composite bypass:

    He made an AES test cart in order to get the correct values for the RGB mod. This basically allowed him to have the Monitor test program (which was needed for the RGB mod testing) and the neo geo diag bios z80 testing all on one cart.

    He looked at the RGB signal with a scope, and took the measurements required and he made a temp RGB amp. It all worked fine and the RGB signal is 0.7vpp exactly as it should be. Afterwards he designed a PCB for it. So in the end, this solution gives 75ohm impedance and 0.7vpp signals (to each R-G-B channel), which is correct to the specs.

    Also removed Composite video and used CSync instead.

    The RGB values after the mod:

    RED.png

    GREEN.png

    BLUE.png

    The RGB mod on the Neo Geo 3-4 board installed



    Last edited by DaytimeDreamer; 04-12-2017 at 04:51 AM.

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    Rest of the pics. Besides the RGB there was a total recap, audio fix and a Unibios installation





    Last edited by DaytimeDreamer; 04-12-2017 at 04:50 AM.

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    Is there a cap on the YM3016 DAC?

    Quote Originally Posted by MKL View Post
    The cap for the DAC (YM3016) seems to make the most difference.
    Nice clear pics!

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    Quote Originally Posted by nam9 View Post
    Is there a cap on the YM3016 DAC?


    Nice clear pics!
    Thanks. I'll be adding even better ones when I received the finished board. I'll also give a link to the guy's service and shop (UK based) for whoever is interested. Hope that's ok with everyone.

    No, there is no amp installed on the YM3016 DAC and it's my fault. Forgot to pass on this info to the guy fixing the board. He'll be adding it now. He will also be adding those 1000pf caps MKL mentioned in his original thread.

    There is also a cap on the preamp 2066D JRC. Electrolytic caps were added to the 4558s so I guess what could be done is done in terms of audio mods/enchancements. Any tech guy (Xian Xi, greatfunky) let me know if all is good from what you see.

    18/04/2017 update:

    2X1000pf caps added
    Swapped cheap ceramics for better quality x7r rated caps
    Added cap to the DAC (YM3016)

    IMG_20170418_132541.jpg
    Last edited by DaytimeDreamer; 04-18-2017 at 11:10 AM.

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    My AES 3-4 came back with all the mods done. Here are some crappy quality iphone 5 videos:

    Neo Geo AES 3-4 revision (RGB + Audio mods) 240P output to Sony Bravia 20S3020 (An old 2007-2008 720p LCD TV)




    Neo Geo AES 3-4 revision (RGB + Audio mods) + OSSC Line 3X mode output to Sony Bravia 20S3020 (scanlines at 31%)



    The audio buzz is gone. You can hear some hiss from if you set the headphone volume at 60% upwards but you must really try to hear it. Then again the audio is really loud with no distortion from 40% upwards.

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    Just recently got a Neo Geo myself, and unfortunately I sort of got suckered by the information floating around that anything below 70k serial was going to be the better RGB. So I got one with a serial of 47334 and it turned out to be a 3-3, which I come to find out now I couldn't have picked a worse revision!

    So I'll have to do the full compliment of mods on mine, including the audio (which does in fact have a 60-cycle hum when I plug my headphones into it). I was wondering if for clarity I could see a finalized list of all the components needed for the audio restoration mod and where each goes? I pretty much get the idea from the posted images, but I just want to be sure I get the right ratings for each cap.

    Below is a quick snap of my 3-3 board, which interestingly has the power regulation roped off to a separate board over the memory card. earlier 3-3 boards in the 30k serial range don't have this daughter board. I'm kind of curious what made SNK make this change mid-revision.

    Neo Geo Mobo - AES3-3 - 47334 - PRO-POW2.jpg

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    My AES3-3 system doesn't have that NEO-POWER board, its serial somewhere in the 40k range, can't remember off the top of my head. The video saturation is a bit weak, but I fail to see how it's a bad revision.

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    Quote Originally Posted by FBX View Post
    Just recently got a Neo Geo myself, and unfortunately I sort of got suckered by the information floating around that anything below 70k serial was going to be the better RGB. So I got one with a serial of 47334 and it turned out to be a 3-3, which I come to find out now I couldn't have picked a worse revision!

    So I'll have to do the full compliment of mods on mine, including the audio (which does in fact have a 60-cycle hum when I plug my headphones into it). I was wondering if for clarity I could see a finalized list of all the components needed for the audio restoration mod and where each goes? I pretty much get the idea from the posted images, but I just want to be sure I get the right ratings for each cap.

    Below is a quick snap of my 3-3 board, which interestingly has the power regulation roped off to a separate board over the memory card. earlier 3-3 boards in the 30k serial range don't have this daughter board. I'm kind of curious what made SNK make this change mid-revision.

    Neo Geo Mobo - AES3-3 - 47334 - PRO-POW2.jpg
    Weird that a 3-3 system has that board. If you check the first post I've opened a thread about a Neo Geo AES I had (now sold to a good friend) which was 3-3

    LINK

    At some point I can open up the 3-4 board and take pics of everything. Probably in the coming days.

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    Quote Originally Posted by HeavyMachineGun View Post
    My AES3-3 system doesn't have that NEO-POWER board, its serial somewhere in the 40k range, can't remember off the top of my head. The video saturation is a bit weak, but I fail to see how it's a bad revision.
    Yeah I'm not exactly sure at what point in the 3-3 revision they started doing this. I have seen one other 3-3 with this exact same power board, and it was some Australian dude that had one just like mine. The serial on mine is 47334, so if you could, let me know what your serial is. I may start a database of serial revisions and see if we can pinpoint when this modification started.

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    Here's my serial, 041738:


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    Thanks! But yeah, turns out the RGB on mine is extremely bad with checkerboarding. Strangely though, plugging the mini headphone cord of my RGB cable into the front audio jack reduces the intensity of the checkerboarding by like 90%.

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    Probably a grounding loop of some sort in the RGB that is corrected when the headphone jack is in use.

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    Quote Originally Posted by HeavyMachineGun View Post
    Probably a grounding loop of some sort in the RGB that is corrected when the headphone jack is in use.
    So get this: I unplugged the scart cable to probe it with a multimeter. Everything checked out fine. Today I plug everything back into the NEO GEO and magically the checkerboading is gone! Even when I unplug the headphone jack, there's zero checkerboarding now. I tested on my physical copy of Fatal Fury Special to make sure it wasn't a NEOSD thing, and that game is also crystal clear now. Only thing I can figure is either the power cord or RGB cable were somehow not fully seated properly, and my re-connecting of all the cables may have fixed the issue.

    At any rate, the RGB is now crystal clear, so I'll take it!

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