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Thread: Just got my AES, video output seems dim, insides look questionable, advice?

  1. #1
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    Just got my AES, video output seems dim, insides look questionable, advice?

    Hi all,

    I'm just joining the ranks of AES owners. I got myself a US AES with a 20-35k serial number as those are supposed to have quality RGB output.

    I use an original PSU through a stepdown converter and an RGB SCART cable of unknown quality (shielded one from RGC coming soon).

    Now, I tried it first on a small crappy TV I use for testing, had some sever scrolling checkerboards. The kind you see when sync bleeds into RGB. On my larger main HDTV those are not visible, but the image looks dim. Like half-range.

    The console looks good from the outside, was supposed to be unmodded apart from a set of stereo RCA jacks on the back. Kinda useless, but whatever.

    I opened the sucker up, here:

    https://imgur.com/a/NzEh9

    Now this looks kinda weird to me. What exactly is this daughterboard? Why is there a wire from the daughterboard to a lifted pin of the video encoder chip?

    Basically, could you tell me what exactly was done to this console, if it is one of the 'good' revisions, what can be done about the brightness issue.

    Much appreciated!

  2. #2
    The Chinese Kid Kid Panda's Avatar
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    Some look like that, it's just part of a revision.

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    The Chinese Kid Kid Panda's Avatar
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    http://www.neo-geo.com/forums/showth...daughter-board

    And to answer your question of what that board is.

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    Very helpful, thanks! Looks really a strange, I've never seen a factory fresh console have this many wires soldered to chip legs...

    How do I know my board revision? Since it doesn't say anything next to NEO GEO it's 3-1/3-2?

    For this board revision http://www.jamma-nation-x.com says

    "RGB Fix - Replace 100uf caps with 470uf value (10v is best fit). You do not need to replace the 68ohm resistors with 75ohm since they aren't 1% resistors but you can replace them for good measure."

    That's going to fix the dim picture or the potential checkerboarding?

    edit:

    Looking at this thread

    http://www.neo-geo.com/forums/showth...S)-motherboard

    if I'm otherwise happy with the picture and only have a brightness issue, I just need to replace the resistors on the RGB lines with weaker ones?
    Last edited by SirRockALot; 11-01-2017 at 03:33 PM.

  5. #5
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    Quote Originally Posted by SirRockALot View Post
    Very helpful, thanks! Looks really a strange, I've never seen a factory fresh console have this many wires soldered to chip legs...

    How do I know my board revision? Since it doesn't say anything next to NEO GEO it's 3-1/3-2?

    For this board revision http://www.jamma-nation-x.com says

    "RGB Fix - Replace 100uf caps with 470uf value (10v is best fit). You do not need to replace the 68ohm resistors with 75ohm since they aren't 1% resistors but you can replace them for good measure."

    That's going to fix the dim picture or the potential checkerboarding?
    Changing the Caps might not do much. I own 2 Aes Consoles that had the same issue. Sent them to Xian Xi and I he just bypassed the rgb on the board and ran it through the Jrok. Picture is much improved now. Not as bright as my 2 slot picture but bright enough were the picture looks good.
    Last edited by RAZO; 11-01-2017 at 03:37 PM.

  6. #6
    JammaNationX
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    Yours looks to already have the resistors and caps swapped out. You can do either an RGB bypass or change the 2.2K resistors on the RGB lines(Higher resistance like 2.5k-2.7k) to brighten the image. Both will achieve the same results.

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    Looking at the picture on my main TV, I'm actually quite happy. There's no distortion, very low noise, no sync issues, no blurring/bleeding. Really just the brightness. In the thread user F-zero mentioned he replaced the resistors on his board with 38Ohm ones to get the brightness up to snuff. I can see I have four 75Ohm resistors right next to the DIN connector, I assume one of them is on csync and the other three are RGB. If I simply replaced those with lower values I think I'd be good? What do you think?

  8. #8
    JammaNationX
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    Quote Originally Posted by SirRockALot View Post
    Looking at the picture on my main TV, I'm actually quite happy. There's no distortion, very low noise, no sync issues, no blurring/bleeding. Really just the brightness. In the thread user F-zero mentioned he replaced the resistors on his board with 38Ohm ones to get the brightness up to snuff. I can see I have four 75Ohm resistors right next to the DIN connector, I assume one of them is on csync and the other three are RGB. If I simply replaced those with lower values I think I'd be good? What do you think?
    That's completely your call but those values are the ones recommended by Sony themselves. I don't think it will hurt anything dropping it a little.

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    Quote Originally Posted by Xian Xi View Post
    Yours looks to already have the resistors and caps swapped out. You can do either an RGB bypass or change the 2.2K resistors on the RGB lines(Higher resistance like 2.5k-2.7k) to brighten the image. Both will achieve the same results.
    Really, so this console has been modified after all? Is there somewhere a guide that explains the resistor fix? I'm a bit confused why higher resistance would give a brighter image and it seems like the resistors close to the DIN jack are 75Ohm not 2.2k?

  10. #10
    JammaNationX
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    Quote Originally Posted by SirRockALot View Post
    Really, so this console has been modified after all? Is there somewhere a guide that explains the resistor fix? I'm a bit confused why higher resistance would give a brighter image and it seems like the resistors close to the DIN jack are 75Ohm not 2.2k?
    The 2.2k resistors are on the middle left side of the board where the RGB is going through prior to the encoder. The resistor/cap combo on the output of the encoder is to fix the ac coupling issues the stock configuration had that caused the curling and loss of sync during bright flashes.

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    Quote Originally Posted by Xian Xi View Post
    The 2.2k resistors are on the middle left side of the board where the RGB is going through prior to the encoder. The resistor/cap combo on the output of the encoder is to fix the ac coupling issues the stock configuration had that caused the curling and loss of sync during bright flashes.
    Sorry for the stupid questions.

    So I can either increase the resistors before the encoder or decrease the ones on the output? I've just read a few places where people fixed this by decreasing the output resistors.

    How do you know that the console has been modified? I noticed that the output caps are already 470uf, not 100uf as labeled on the board. Also the resistors on the output are 75Ohm, but the board labels them as 68. Is that it?

    Also running the console for a while, I notice that the checkerboard pattern comes back :/ If I reset it its gone again, but appears again later. Is the daughter board supposed to fix this? What could be the issue here? I noticed that the adjustment pot on the daughterboard can be used to make the checkerboard pattern scroll left/right/stop it, but it never makes it go away. Like I said, on my main TV it's only visible after a while, my smaller TV shows it heavily all the time.
    Last edited by SirRockALot; 11-01-2017 at 05:54 PM.

  12. #12
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    75 Ohms is the normalized value of video cable impedance, so the best way is to increase input resistors.

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    Quote Originally Posted by nono2lozere View Post
    75 Ohms is the normalized value of video cable impedance, so the best way is to increase input resistors.
    Why are they 68Ohm on the unmodified board? Just curious why they designed the console that way.

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    just because 68 Ohms is standart value.
    And if it's just brightness, why don't you increase it on your TV?

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    I don't think that's going to help. I probably have to crank up the RGB bias, tried that on my TV, still looks to dark. I'd rather properly fix this. And then there's the issue of the checkerboards. Like I said, one TV has them really bad, the other one just has them appear after a while. I found this YouTube comment:

    "I've been curious. I purchased a neogeo gold system back in the mid 90's. When i first got it, I noticed a weird video effect where it looked like there was a window screen overlayed on the screen and it moved from left to right. I sent the neo into SNK and when I got it back, there was that beige board in it. It seems like that board stopped the 'interference' from scrolling. You could still notice the interference moving left to right when you 1st powered the unit on but it stopped. My question.. What the hell was the function of that board they installed and what exactly did it do? ....That weird interference was still there but it wasn't scrolling through the video image. It seems like it caused edges of displayed objects to have a jagged look. What was that board? If you don't know about the "interference" I'm talking about, give that little trimmer cap/pot a twist when the system is on and you'll be able to see that "window screen" effect that I'm talking about. The 15/16 year old teenage boy in me NEEDS to know what that board did. I kind of wish that the interference just moved really fast instead of being stationary. I played the MVS a lot before I got the home system. It is still one of the biggest mysteries of my teenage years."

    This daughter board should fix the checkerboards? Doesn't really seem to work.

    So it seems like I got a console that has already been tampered with and has a severe brightness & checkerboard defect. I was hoping I'd get a good model because the serial number range.

    I'd be grateful for any advice on how to salvage this...

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    Thanks, as I suspected this board only helps with composite video, which I won't need. So this board is basically useless and is likely only causing interference for me? Should I remove it?

    Also, I noticed the crappy cable I have is tapping sync from composite instead of csync. I already ordered a proper csync cable. Might those artifacts go away with a proper cable?

    I'm not an electronics experts so these things are not entirely clear to me. Any idiot-proof advice on what to do about the brightness and checkerboarding would be very helpful ;-)

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    Update:

    I modified by crappy cable from sync-over-composite to csync, and this fixes the checkerboarding. Looks like the composhit/sync only bleeds into RGB in the cable, not on the motherboard. So no more issues with a proper csync cable.

    I did some more searching & reading on the brightness issue, basically I need to do this...

    https://shmups.system11.org/viewtopi...06d3e#p1269037

    ...correct? Swap three 2.2kO resistors with three 3.0kO ones?

    Thanks!

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    Thanks Xian Xi, very helpful! If I ever get rich and famous with my AES repair skills, I'll be sure to attribute it all to you.

    If you could please indulge two more questions:

    - I noticed that on my board the 2.2K labeled resistors in the voltage divider are actually 1.5K (https://i.imgur.com/8Rj0HdF.jpg). WTF? Do you still think I should try replacing them with 2.8K or try on-spec 2.2K first?

    - As you observed before, my board already has the 68Ohm -> 75Ohm and 100uF -> 470uF fixes on the output side, but the input side still has 0.1uF caps. If I only have brightness issues can I just leave them like that or should I replace them with 1uF caps like on later board revisions?

    Thanks!
    scanlines are horizontal jailbars

  22. #22
    JammaNationX
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    Quote Originally Posted by SirRockALot View Post
    Thanks Xian Xi, very helpful! If I ever get rich and famous with my AES repair skills, I'll be sure to attribute it all to you.

    If you could please indulge two more questions:

    - I noticed that on my board the 2.2K labeled resistors in the voltage divider are actually 1.5K (https://i.imgur.com/8Rj0HdF.jpg). WTF? Do you still think I should try replacing them with 2.8K or try on-spec 2.2K first?

    - As you observed before, my board already has the 68Ohm -> 75Ohm and 100uF -> 470uF fixes on the output side, but the input side still has 0.1uF caps. If I only have brightness issues can I just leave them like that or should I replace them with 1uF caps like on later board revisions?

    Thanks!
    1.5k, WTF, no wonder why it's dim. I'd first try putting it back at 2.2k 1/4 watt, 1% if you can but doesn't need to be. And then go from there. If the 2.2k makes it perfect then you are done, if it's not bright enough, increase the resistance by 200-300 like 2.4k-2.5k, it should be bright at that point.

    As for the input caps, just leave them as stock.

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    Thanks a lot, that sounds like a plan!

    Now, I need to figure out how I'll do this given my extremely poor soldering skills...

    Desoldering is problematic in my experience. Sometimes I can desolder even bigger components with ease using my pump/wick, other times I have zero luck getting even a simple capacitor out. Solder won't meld, even after trying to reflow with fresh solder and using flux, or I simply can't clear the via afterwards. I also notice when practicing that after removing and re-soldering a component a few times the pads generally break from scraping them with the iron, mechanical stresses, heat etc. So I don't think I can reliably remove those three resistors and then try multiple values till I found a good sweet spot. I'd likely damage the board.

    I'm thinking the easiest way would be to solder a pair of short wires to the resistor legs and the pad, then clip the existing resistors off with electrical pliers and try out the various resistor candidates at the ends of those short stand-off wires. This is still risky as I find even the mechanical stress from cutting off a component leg can sometimes rip a pad from the board, but it's the safest route I can think of.

    Do you think that's a stupid plan or is that an OK approach for soldering beginner?
    scanlines are horizontal jailbars

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    Quote Originally Posted by SirRockALot View Post
    Thanks a lot, that sounds like a plan!

    Now, I need to figure out how I'll do this given my extremely poor soldering skills...

    Desoldering is problematic in my experience. Sometimes I can desolder even bigger components with ease using my pump/wick, other times I have zero luck getting even a simple capacitor out. Solder won't meld, even after trying to reflow with fresh solder and using flux, or I simply can't clear the via afterwards. I also notice when practicing that after removing and re-soldering a component a few times the pads generally break from scraping them with the iron, mechanical stresses, heat etc. So I don't think I can reliably remove those three resistors and then try multiple values till I found a good sweet spot. I'd likely damage the board.

    I'm thinking the easiest way would be to solder a pair of short wires to the resistor legs and the pad, then clip the existing resistors off with electrical pliers and try out the various resistor candidates at the ends of those short stand-off wires. This is still risky as I find even the mechanical stress from cutting off a component leg can sometimes rip a pad from the board, but it's the safest route I can think of.

    Do you think that's a stupid plan or is that an OK approach for soldering beginner?
    It won't work because two resistors in parallel always have a smaller value than the smallest resistor (R=(R1+R2)/(R1*R2)).

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    I know, but I wrote "clip the existing resistors off with electrical pliers". What do you think?
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