NEO-MVH MV2F issues

aha2940 · Jun 13, 2015

Hi

I got one of these MVS boards for a low price. When I tested it, it gave me backup memory error. However, I installed a UniBIOS 3.2 on it, bypassed the memory error and got what you see in the pics. The address error got it when I tried to force the board into AES mode (pressing B after the first error pic). Can anybody please shed any light on how to solve the memory issue or the video issue? The test cart was KoF97, it shows the exact same thing no matter the slot I use for the cart, they have been cleaned well. If more pics are needed, just let me know please.

Thanks!!

Pics:

Xian Xi · Jun 13, 2015

Usually if the error doesn't show a 5555 and instead part of it shows 00 it means that it's missing control signals. It also looks like you have ZMC2 problems. Both probably caused by a leaking battery.

aha2940 · Jun 13, 2015

Xian Xi said:
Usually if the error doesn't show a 5555 and instead part of it shows 00 it means that it's missing control signals. It also looks like you have ZMC2 problems. Both probably caused by a leaking battery.

Thanks Xian Xi. The battery did not leak, I got the board with it and first thing I did was replacing it with a battery holder, however some of the traces do look corroded in the zone you told, maybe some are broken. Any clue which traces should I check?

Thanks!

kuze · Jun 13, 2015

aha2940 said:
Thanks Xian Xi. The battery did not leak, I got the board with it and first thing I did was replacing it with a battery holder, however some of the traces do look corroded in the zone you told, maybe some are broken. Any clue which traces should I check?

Thanks!

Start with the ones that look corroded.

Also this info may be helpful:
https://wiki.neogeodev.org/index.php?title=NEO-ZMC2
http://newlifegames.net/nlg/index.php?topic=152.0

aha2940 · Jun 13, 2015

kuze said:
Start with the ones that look corroded.

Also this info may be helpful:
https://wiki.neogeodev.org/index.php?title=NEO-ZMC2
http://newlifegames.net/nlg/index.php?topic=152.0

Thanks for the help, guys. I tested all traces from the NEO-ZMC2 to the nearest via/component and all tested OK, however there are many pins on this chip that do not seem to have anything connected to them. Take a look at pins 43 to 64 in the following pic: what are they connected to?

Thanks for any help with this.

Atro · Jun 13, 2015

If it's not the ZMC, you're unfortunately screwed.
You have certainly one or more NEO257's faulty.

I had the same issues as you're having, but not as bad tho.
Xian sent me a few 257's that I later swapped.

The problem is that the 257's are only present on MV2's. And to save an MV2 with this issue, you have to kill an other.
I feel you buddy. I had 2 at one time, expecting to use one as a donor. Unfortunately both had the same issue.
There's 3 257's on those boards. The rightmost one is usually flawless as the battery leak don't reach that area.

aha2940 · Jun 13, 2015

Atro said:
If it's not the ZMC, you're unfortunately screwed.
You have certainly one or more NEO257's faulty.

I had the same issues as you're having, but not as bad tho.
Xian sent me a few 257's that I later swapped.

The problem is that the 257's are only present on MV2's. And to save an MV2 with this issue, you have to kill an other.
I feel you buddy. I had 2 at one time, expecting to use one as a donor. Unfortunately both had the same issue.
There's 3 257's on those boards. The rightmost one is usually flawless as the battery leak don't reach that area.

Ah, damn that's exactly what I was fearing...is there anything I can do to test these NEO-257s? I have a logic probe if it's any useful.

Thanks!

GadgetUK · Jun 14, 2015

Look at the connections on that ZMC2 - there's rust and corrosion all over the place there (see pins 65 to 80), and around the surrounding chips. Clean up, flux and reflow, measure connectivity on ZMC2 and the 257's. It's almost certainly related to that rust and corrosion.

Atro · Jun 14, 2015

GadgetUK said:
Look at the connections on that ZMC2 - there's rust and corrosion all over the place there (see pins 65 to 80), and around the surrounding chips. Clean up, flux and reflow, measure connectivity on ZMC2 and the 257's. It's almost certainly related to that rust and corrosion.

That would be excellent if it comes only from there.
ZMC2's can be found on any spare MVS board. 257's are sadly a different story...

aha2940 · Jun 14, 2015

GadgetUK said:
Look at the connections on that ZMC2 - there's rust and corrosion all over the place there (see pins 65 to 80), and around the surrounding chips. Clean up, flux and reflow, measure connectivity on ZMC2 and the 257's. It's almost certainly related to that rust and corrosion.

Thanks for your help, any advice on what product to use for cleaning the corrosion without damaging the board?

Atro said:
That would be excellent if it comes only from there.
ZMC2's can be found on any spare MVS board. 257's are sadly a different story...

You are right, I also believe most (all?) AES carts have one inside. I have a broken AES KoF 94 cart somewhere, I could use its ZMC2 if needed.

Thanks!!

aha2940 · Jun 20, 2015

Hi

I'm looking for something to better clean the corrosion from this board, and I've read everywhere that deoxit is the way to go, however they seem to have several products (http://www.caig.com) which one is the best one for this job? also, how much should one get? like, a bing can or maybe a smaller can?

Thanks!!

Xian Xi · Jun 20, 2015

I would just remove the ZMC2 as it's most likely rusted inside the housing already if the corrosion on the legs near the body are that bad. For corrosion I usually use a fiber pen and remove it completely and then brush green nail polish over it to seal it back up. Exposing the copper that way sometimes shows breaks in the traces from corrosion.

aha2940 · Jun 20, 2015

Xian Xi said:
I would just remove the ZMC2 as it's most likely rusted inside the housing already if the corrosion on the legs near the body are that bad. For corrosion I usually use a fiber pen and remove it completely and then brush green nail polish over it to seal it back up. Exposing the copper that way sometimes shows breaks in the traces from corrosion.

Man...I can remove the chip almost for sure, however I am also pretty sure I cannot solder another one in place, my equipment is simple (just a weller soldering iron with default tip). How much would you charge for this repair? I can get you an AES board with the ZMC2 chip.

Thanks!!

Xian Xi · Jun 20, 2015

aha2940 said:
Man...I can remove the chip almost for sure, however I am also pretty sure I cannot solder another one in place, my equipment is simple (just a weller soldering iron with default tip). How much would you charge for this repair? I can get you an AES board with the ZMC2 chip.

Thanks!!

I'm not doing repairs right now due to being overwhelmed with project builds. Sometimes I just use chipquik instead of the hot air station since it's quicker, costs a bit more but I actually reuse the product when I'm done.

aha2940 · Jun 20, 2015

Xian Xi said:
I'm not doing repairs right now due to being overwhelmed with project builds. Sometimes I just use chipquik instead of the hot air station since it's quicker, costs a bit more but I actually reuse the product when I'm done.

Thanks for the suggestion man, that chipquik stuff seems right for removing this chip, however what worries me more is the process of soldering the new chip back in place, because I've seen videos where they do it but my equipment does not seem to work for that.

Xian Xi · Jun 21, 2015

aha2940 said:
Thanks for the suggestion man, that chipquik stuff seems right for removing this chip, however what worries me more is the process of soldering the new chip back in place, because I've seen videos where they do it but my equipment does not seem to work for that.

I use a regular soldering iron when I solder qfps onto mobos, nothing special. Just make sure you clean all the solder pads on the mobo. I do that by applying flux on the solder pads and then using desoldering braid and your soldering iron you run the braid over the pad gently and in the direction of the pad(not side to side unless you have experience doing it that way). Once the solder pads are clean, apply some flux to the solder pads again, place the chip on the board using the markings to line up Pin 1. Then I apply flux to the legs as well. Then I line everything up, while pushing down on the chip with my left thumb/finger I then apply a little solder to the corner pins to hold the chip in place and keep it lined up. Then just solder the rest. Make sure you use enough solder to get a proper heel on each leg. If you have one available, you can use a wave soldering tip for your soldering iron.

NEO-MVH MV2F issues

aha2940

AH, A, COLUMBIAN!,

Xian Xi

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aha2940

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kuze

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aha2940

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Atro

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aha2940

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GadgetUK

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Atro

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aha2940

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aha2940

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Xian Xi

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aha2940

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Xian Xi

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aha2940

AH, A, COLUMBIAN!,

Xian Xi

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