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Thread: Neo Geo bad video (green)

  1. #1
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    Neo Geo bad video (green)

    I've consolized another neo geo and I get a lot of green. The crosshatch and gameplay are all green when using component from a jrok rgb encoder. I've replaced DAC resistors, the LS273's and still no good. In fact, at one point it was worse and lost the blue border on the crosshatch screen all together. Any help would be appreciatedScreenshot_20190119-131938_Messenger.jpgreceived_262749824440554.jpeg

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    What motherboard are you using here?
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    JammaNationX
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    Check the output resistors on the JROK for Component. I’ve had times in the past where some weren’t soldered on good.

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    Problems like this arw why I always keep an RGB test monitor around. This definitely looks like a problem with your encoder and not the Neo Geo

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    This one is an MV1ACH but I've also tried the same encoder on an MV1B with the same results. I did hook up the jrok encoder to a sega genesis to see if it was the encoder and the picture seemed fine. It was a little on the dark side though..

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    they all seem to be in good order, I also tested the s video output and I got orange and black and white stripes.

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    Test your resistor values on solder side under U9, U8 and U6 and see if they are correct.
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    Quote Originally Posted by DasiyAge View Post
    they all seem to be in good order, I also tested the s video output and I got orange and black and white stripes.
    I believe I talked to you Xian Xi a while ago and you said it might be a sync issue? The encoder worked fine on my first neogeo but all the ones I've tried now have had color issues.

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    Do the resistors need to be out of circuit for accurate reading?

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    Everything looks within range, though I can't be 100% sure. I don't have a microscope to read the values on the resistors

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    I didn't have to because I had another board to compare and one of the values of the resistor was way off from where it should have been but to be more specific you want to check the resistors for VID- RED GRN & BLUE at the edge connector R48=RED, R62=BLUE & GREEN= R57
    I had a very similar problem BUT with an MV1B
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    Quote Originally Posted by DasiyAge View Post
    Do the resistors need to be out of circuit for accurate reading?
    Last edited by BIG BEAR; 02-26-2019 at 01:33 PM.

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    Do you remember those values? I have an MV1B with me that has the same issue

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    No but I can give you the values of a good MV1B and you can compare.
    I'm pretty certain I had the exact same problem.
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    Last edited by BIG BEAR; 02-26-2019 at 07:57 PM.

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    That'd be phenomenal. Whenever you get a chance please

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    OK. With the 1B, the problem was @ U6 chip(pin 6) connected to R74 or I could be wrong and it's between pin 2-8.Here is the read out I get and if something is way off it needs to be replaced.
    R61- 219.3 OHMS
    R60- 464.8 OHMS
    R59- .990 KILO OHMS
    R58- 2.122 KILO OHMS
    R65- 2.170 KILO OHMS
    R66- .994 KILO OHMS
    R67- 462.8 OHMS
    R68- 221.5 OHMS
    R75- 221.9 OHMS
    R74- 460 OHMS
    R73- .977 KILO OHMS
    R72- 2.117 KILO OHMS
    BB

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    JammaNationX
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    Can you post the color bars using a Unibios?

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    Quote Originally Posted by Xian Xi View Post
    Can you post the color bars using a Unibios?
    No sorry I don't have unibios or this might be a lot easier. And thank you Big Bear I'll get to checking those values tonight!

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    Quote Originally Posted by BIG BEAR View Post
    OK. With the 1B, the problem was @ U6 chip(pin 6) connected to R74 or I could be wrong and it's between pin 2-8.Here is the read out I get and if something is way off it needs to be replaced.
    R61- 219.3 OHMS
    R60- 464.8 OHMS
    R59- .990 KILO OHMS
    R58- 2.122 KILO OHMS
    R65- 2.170 KILO OHMS
    R66- .994 KILO OHMS
    R67- 462.8 OHMS
    R68- 221.5 OHMS
    R75- 221.9 OHMS
    R74- 460 OHMS
    R73- .977 KILO OHMS
    R72- 2.117 KILO OHMS
    BB
    Alright I had some time and checked and none of my values were more than 10 ohms off, so in my experience that wouldn't make such drastic changes. Also I should add that I swapped U6 and U7 with a set from the first MVS I consolized so that I could rule out the 273's. I believe that was a recommendation from Jamma nation X. That leaves either my JROK encoder or a bad sync signal I guess
    Last edited by DasiyAge; 03-01-2019 at 01:52 PM.

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    JammaNationX
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    Is Svideo and composite the same or are those two signals correct?

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    never tested composite since I'd never use it but if I remember correctly svideo was orange instead of green and there were occasionally black and white lines running across the picture

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    So with all this should I assume it's the encoder? I find it hard to believe 3 mobos were all shot in the same way

  22. #22
    JammaNationX
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    I’d use a sync cleaner first.

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    Have you seen the JROK ones anywhere? Last time I saw one it cost twice as much as its worth in shipping

  24. #24
    JammaNationX
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    I can sell you one for $10 shipped

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    Wow dude thanks so much, how should I contact you about it?

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