Offical Omega CMVS Tech Support Thread

SamIAm

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Hey everyone, first post here. Happy new year!

I bought an Omega a couple of months ago. Just on the 26th of December, I finally got my first cart for it, which was a 120-in-1. It appeared to work just fine at first, but I only tested it for about 30 minutes.

Then the other day, when I finally had a day off to play with it, a problem just like this showed up. I swiped the picture from http://wiki.aussiearcade.com.au/index.php/PCB_Repair_Logs_Neo_Geo_6_Slot

Pcb_repair_neogeo_6_slot_2_4_zpsf52a0f79.jpg


It's been somewhat intermittent, but it hasn't completely disappeared since. It does not occur on any Neo Geo splash screen, in the bios, or in the select screen for the multicart.

So, from what I've read, this is simply a connection problem with one of the lines leading to the graphics data on the cartridge. Before you say "clean the cartridge slot", though, let me tell you that I have done that literally 10+ times now, and I don't think that's it. At one point, I was using a very nice kind of thick paperboard with big fibers that scrubbed the contacts very well, and I got a lot off at first. Yet at present, even with a bit of alcohol, I can't get another spec. Yes, it could be some kind of material stuck in there that will need proper contact cleaner. However, when I poke at the cartridge with the system running, I get zero reaction on the screen. The 120-in-1 was brand new, too. I just don't think a dirty slot is the problem.

Today, I ordered a real MVS cartridge just to help make sure that it's not my 120-in-1. But if indeed that's not it, then I'll be in a bit of a pickle. I live in Japan, and sending this back to the US for repair would require $60-$80 round trip on the shipping alone. It would be nice if I could fix it. However, I am not a particularly skilled fellow at such things.

What do you think I should do? I've sent an email to shadowkn55, but I thought I should ask people here, too.

And by the way, this wouldn't by any chance have anything to do with Japan's power being at 100v while the US is 120v, would it?

Thank you!
 

SamIAm

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It occurs to me that I probably should have only linked to that site rather than also directly copying its picture. I apologize if that was a violation of etiquette, and I would edit that post if I could.
 

shadowkn55

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I just check that switching the polarity on the ac power cord has no adverse effect on the system or the power supply. It should work fine in any outlet in your house including the ones without a grounding prong. The 100VAC coming from your wall shouldn't be an issue either. The internal PSU goes from 90ish to 260-some so all bases are covered worldwide.

To answer your question about the graphics, it looks like a data line issue on the C-roms. The first thing to rule out is the cartridge so try getting a couple legit cards and see if that helps. If it turns out to be a system issue, you'll have to send it back and I'll swap it with another fully working system.
 

SamIAm

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Hello shadowkn55! Thank you very much for your reply.

First, I appreciate that you looked into the power supply question for me. My apartment only has a couple of three prong outlets, and the one that I was using to hook up the Omega had to be permanently relinquished to something else last weekend. It's also good to know that there's no issue with the voltage. Step up converters aren't super expensive, but I would just as soon save the $30.

I bought a legit cart the other day, and it is scheduled to arrive on the 8th. If it also shows the line effect, I'll buy one more just to make doubly sure that the problem really does lie with the system itself (not to mention, I want some legit carts of my favorite games anyway). I'm honestly hoping that it does work, because getting another 120-in-1 and/or trying to fix the one I have really isn't a big deal.

I also bought some genuine electrical contact cleaner just in case. It should arrive on the 8th as well. I will report back then.

I turned the system on this morning, and for the second time ever, a curious thing happened. The line effect did not appear immediately. However, there were a few odd blinking pixels on the screen right from the start. Then, over the course of the next few minutes, the lines slowly came on, becoming more and more prevalent until they filled the screen. It really seems like there's a connection that is just barely failing to happen.

Can you or anyone else tell me where the suspect C-rom data lines exist on the cartridge? I would like to open up my 120-in-1 and take a really careful look at it. If you think it's all right, I might try taking the PCB out of the plastic case, plugging it in, and very carefully and gently flexing it while the system is running. If there's a micro-tear in a data line somewhere in the cart, that should cause a change in the effect onscreen. As I said before, bumping the cart in the slot or wobbling the system itself while it is running causes absolutely no reaction on the screen (Note: I do this super-gently, so please don't worry). But, if there's a problem with a data line in the cart itself, I would think that this would cause at least some visible reaction.
 

kuze

Akari's Big Brother
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I've had a similar effect occur with the 161 in 1 cart on my 2 slot board, iirc I just reseated the cart and the issue was resolved.
 

SamIAm

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The C-rom lines are on the CHA board (the bottom one). There are 32 of them total from CR0-CR31.

^^^Thanks, but believe me, I've spent a couple of hours cleaning, reseating, recleaning and rereseating and more. Either there is some tremendous gunk on the contacts, or there is a damaged circuit somewhere in the cart or the system itself.

https://wiki.neogeodev.org/index.php?title=MVS_cartridge_pinout

Great, thank you. I will see what I can see as soon as I get home today.
 

SamIAm

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As a new member here, I know it's not my place to complain, but I really don't get why new members can't edit their posts.

(I put some text in the wrong place in my post above by accident, and it's all goofed up.)
 

shadowkn55

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As a new member here, I know it's not my place to complain, but I really don't get why new members can't edit their posts.

(I put some text in the wrong place in my post above by accident, and it's all goofed up.)

It makes it easier for new members to meltdown. :snack:
 

aha2940

AH, A, COLUMBIAN!,
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I think I'm going to like it here.

Oh you will. Just obey the rules, respect the marketplace usage (read its rules!!) and participate in the discussion. These are great forums filled with nice people.

Regards.
 

SamIAm

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^^^Thanks, man.

Little update: I didn't have time to try much last night, but I noticed something when I looked into the system through the cart port. On the MV-1C board, there's a great big chip right below the cartridge slot, in the middle-right of the board. Is that the video processor? Googling MV-1C, I can see that this is the biggest chip on the board.

There are two things I could see on it that are suspect:

1. One of the legs of this chip is bent toward the one right next to it. I can't see whether it's actually touching, but it's definitely bent. It a corner leg, so it only has one other leg next to it, and it should be easy to fix. I think I could unbend it with a little push using an exacto-knife. However, I worry about how flexible the metal is. Would it be easy to snap it off? I also assume that I would need to take extra care to ground myself and the knife, right?

2. There's piece of dust or something under some of the other legs. It's like a 1-2mm wide grey blob, and it's really under the legs. I think it would take a can of compressed air to get it out.

shadowkn55: I'll continue to wait for the real MVS cart and the contact cleaner to arrive, but if the system still gives me trouble after I try them, would you like me to attempt fix those two things myself?
 

shadowkn55

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^^^Thanks, man.

Little update: I didn't have time to try much last night, but I noticed something when I looked into the system through the cart port. On the MV-1C board, there's a great big chip right below the cartridge slot, in the middle-right of the board. Is that the video processor? Googling MV-1C, I can see that this is the biggest chip on the board.

There are two things I could see on it that are suspect:

1. One of the legs of this chip is bent toward the one right next to it. I can't see whether it's actually touching, but it's definitely bent. It a corner leg, so it only has one other leg next to it, and it should be easy to fix. I think I could unbend it with a little push using an exacto-knife. However, I worry about how flexible the metal is. Would it be easy to snap it off? I also assume that I would need to take extra care to ground myself and the knife, right?

2. There's piece of dust or something under some of the other legs. It's like a 1-2mm wide grey blob, and it's really under the legs. I think it would take a can of compressed air to get it out.

shadowkn55: I'll continue to wait for the real MVS cart and the contact cleaner to arrive, but if the system still gives me trouble after I try them, would you like me to attempt fix those two things myself?

The big chip you're seeing is the graphics chips. An exacto-knife would be the best way to create some space between the legs but still do it carefully. I would at least wait till the real carts come in before trying it though.

Is the gray blob on the graphics chip or the smaller chip to the left. There is a small dab of hot glue on the left chip to insulate the wire to provides the memory card signal for the VMC.
 

SamIAm

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The grey blob is under the legs of the graphics chip. It's actually just a few legs down from the bent one. I know dust shouldn't be conductive, but it couldn't hurt to get rid of this thing.
 

SamIAm

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Tonight I opened up the system. Those rubber pads were easier to get off than I expected.

The good news is that the bent leg on the corner is definitely not bent enough to touch the one next to it.

The bad news is that the grey blob is not dust. It's some kind of gunk. I took a picture, but my camera isn't good enough to get in on those pins in as much detail as I would like.

View attachment 21804

Can you see that there's one pin that's a different color from the others? It's the 7th one from the left. Look behind there. The grey stuff shows up as a slightly different color. I'm not sure how much of that is supposed to be there, but I've scratched at the area with an exacto-knife, and crud comes up. There's actually a bit of crud around the neighboring pins as well. Also, that one pin sticks out a little bit, as you can see, and it's the only one on the whole chip to do so. It actually doesn't look like it's attached to anything, though.

The contact cleaner that I ordered is supposed to evaporate without leaving a residue. If it's OK with you, shadowkn55, I would like to apply a little bit of it to this area. That is, if the real MVS cart shows the same symptoms. The cleaner is supposed to break down residues pretty well without damaging anything important, and it's advertised specifically for motherboards, so I think it's safe with the plastics.

Big question: See how there's a white line that surrounds this chip under the legs? Should I be able to see that completely? Because there are a few spots on two of the four sides of the chip that are obscured by something. I don't know if it's gunk or something that's supposed to be there. You can see pretty well what I'm talking about in the picture, both in the spot I pointed out and to the right of that.
 
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shadowkn55

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Your attachment isn't working. Can you upload it elsewhere?
 

Niko

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The graphical issues you are reporting are common problems with the multicarts. The issue is that these carts when produced are soldered by hand and not in a reflow oven. So you often end up with bridged connections on some of the eproms, usually closer toward the corners of the chips. Sometimes the issues wont show up for awhile, or only affect certain games.

If you dont mind using a soldering iron, its a pretty simple fix. First get yourself a non corrosive flux pen, and a soldering iron. Then inspect each of the eproms and when you find one with solder bridging the legs. Take the flux pen and run it down all the legs on that side of the eprom. Next take your soldering iron, and starting at the effected area, drag it across the legs horizontally all the way down the eprom. The soldering iron will pickup the excess solder and you should be left with a clean surface mount eprom. If the iron doesnt pickup all the solder, then clean the tip and repeat the process. Sometimes you may need to repeat the process a few times to get all the solder, also having a magnifying glass really helps.

This technique is known as drag soldering and is very useful when working with surface mount components.
 
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SamIAm

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Your attachment isn't working. Can you upload it elsewhere?

Here's the pic I tried to post before. You can see that the bent leg, which is on the left of this row, doesn't look so bent from this angle.

100_1069_zps46bbe2d7.jpg


Here's another pic, this time of a different side of the chip. See the white line under the legs? See how it's obscured by something? Is that normal? EDIT: Also, look at the blackened traces right next to the print "R49".

100_1074_zps0aae3e8d.jpg


The graphical issues you are reporting are common problems with the multicarts. The issue is that these carts when produced are soldered by hand and not in a reflow oven. So you often end up with bridged connections on some of the eproms, usually closer toward the corners of the chips. Sometimes the issues wont show up for awhile, or only affect certain games.

If you dont mind using a soldering iron, its a pretty simple fix. First get yourself a non corrosive flux pen, and a soldering iron. Then inspect each of the eproms and when you find one with solder bridging the legs. Take the flux pen and run it down all the legs on that side of the eprom. Next take your soldering iron, and starting at the effected area, drag it across the legs horizontally all the way down the eprom. The soldering iron will pickup the excess solder and you should be left with a clean surface mount eprom. If the iron doesnt pickup all the solder, then clean the tip and repeat the process. Sometimes you may need to repeat the process a few times to get all the solder, also having a magnifying glass really helps.

This technique is known as drag soldering and is very useful when working with surface mount components.

Whoa, I noticed some bridged eeprom connections in the cart, but they stood out so much I assumed they had to be on purpose. Are you sure these aren't supposed to be there?

100_1073_zps44c38c3d.jpg


Sorry for the angled pic. You can actually make out a couple bridged spots on the far sides as well.

Bear in mind, there is no difference between how the games run. They all show the line effect equally, as far as I have looked anyway, and I've tried quite a few.
 
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Niko

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Whoa, I noticed some bridged eeprom connections in the cart, but they stood out so much I assumed they had to be on purpose. Are you sure these aren't supposed to be there?

100_1073_zps44c38c3d.jpg


Sorry for the angled pic. You can actually make out a couple bridged spots on the far sides as well.

Bear in mind, there is no difference between how the games run. They all show the line effect equally, as far as I have looked anyway, and I've tried quite a few.

Yep, Sometimes they dont matter or cause problems because most of the corner pins are ground or N.C. ( No Connect ). But sometimes important pins are bridged which casues issues. Whenever I fix the boards I always clean up all the bridges since its hard to pinpoint which one is causing the issues.

Also, if you are having the issues in all games then the problem is probably located on one of the "PCMs" or other ICs which are a little better about having a cleaner solder job due to the finer pin pitch. But its not rare for a few of the PCM's pins to be bridged aswell.

Also, since your having graphical issues your problem would be located on the S or C eproms since they handle graphical data. V eproms are for audio samples. So if the audio is fine you can save some time and probably skip fixing the V eproms or releated PCMs.
 
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SamIAm

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Thanks for the info. It's nice to know what those different eeproms are for.

So, there really and truly aren't any pins that are actually supposed to be bridged? I'll have to take one more careful look when I get home tonight. I don't have any flux at the moment, but unbridging those pins is something I think I can handle.

If it's not there already when I get home today, I should be getting both a genuine MVS cart and the motherboard contact cleaner in the mail tomorrow. shadowkn55, please do let me know what you think of those shots of the graphics chip, and also if I would be voiding your warranty, so to speak, by using that cleaner on it. That's assuming that the genuine MVS cart also shows lines and it looks like the problem is on the system side, of course.

EDIT: Hmm, now I am not so sure about using the contact cleaner on the graphics chip. I was misremembering what I read about it when I said it doesn't leave a residue. It came today, and the ingredients are petroleum based. It's also designed to break down carbon-based contaminants more than anything else. I think going for some pure alcohol would probably be better.

So, I took that exacto-knife to the chip again, and I noticed another little thing. The blade can move freely and easily between the legs of the chip. However, in all of those dark areas, it can't. I'm really thinking that all the stuff blocking the view of that white line is some kind of gunk that isn't supposed to be there.
 
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Niko

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Thanks for the info. It's nice to know what those different eeproms are for.

So, there really and truly aren't any pins that are actually supposed to be bridged? I'll have to take one more careful look when I get home tonight. I don't have any flux at the moment, but unbridging those pins is something I think I can handle.

If it's not there already when I get home today, I should be getting both a genuine MVS cart and the motherboard contact cleaner in the mail tomorrow. shadowkn55, please do let me know what you think of those shots of the graphics ship, and also if I would be voiding your warranty, so to speak, by using that cleaner on it. That's assuming that the genuine MVS cart also shows lines and it looks like the problem is on the system side, of course.

EDIT: Hmm, now I am not so sure about using the contact cleaner on the graphics chip. I was misremembering what I read about it when I said it doesn't leave a residue. It came today, and the ingredients are petroleum based. It's also designed to break down carbon-based contaminants more than anything else. I think going for some pure alcohol would probably be better.

So, I took that exacto-knife to the chip again, and I noticed another little thing. The blade can move freely and easily between the legs of the chip. However, in all of those dark areas, it can't. I'm really thinking that all the stuff blocking the view of that white line is some kind of gunk that isn't supposed to be there.


Correct, none of the pins are supposed to be bridged. Alot of the time it doesnt matter though, just depends on the pins. You can always lookup the datasheet on the eprom and get a better idea of which pins shouldnt be bridged. Also make sure you take your time and I cant stress enough how helpful a magnifying glass is for inspecting the eproms before and after debridging the pins.
 

SamIAm

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Thanks again. I'll have a look tomorrow at whatever datasheets I can find. I did notice a couple bridged pins on the other board, which I assume are graphics related, but once again they were on the corners.

I have to say that I'm more suspicious of that gunk around the graphics processor than any bridged connection in the cart, though. I would think that a big bridge made out of solder would cause a pretty consistent problem. What I see, though, varies a lot over time. Sometimes I can start the system up and see almost nothing wrong at first, but the lines will grow bigger and bigger.

Whatever that gunk is, it's on there good. I put a little distilled water on a q-tip and rubbed it on the trouble spots, but the q-tip got up nothing. I don't think it's rust, anyway.
 
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SamIAm

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Update: The real MVS cart came. It has the exact same trouble as the 120-in-1, suggesting a problem with the system itself.

shadowkn55, what would you like me to do? I don't mind going and getting some pure alcohol, and I also don't mind trying the contact cleaner, maybe letting it soak on there for a while and then going at it with a toothbrush. Beyond that, I don't have much confidence at being able to fix this.

EDIT: I bought a little pure alcohol, and I'll try it when I get home today unless I hear otherwise.
 
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shadowkn55

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It seems like you've done all you can in terms of cleaning. I did see a pin on the GRZ chip that did look a little suspect. PM me and we'll discuss repair options.
 

Larrs888

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Hi all,

I just have a query regarding the backup ram and soft dips. My omega has the coin battery mod fitted and I have had my console unplugged for about 2-3 weeks (moving stuff at the moment), tonight I fire the beauty back up and noticed all my soft dips such as blood in Metal Slug X has been reset. How long should the battery keep settings for once unplugged, are these rechargeable or do I need a new battery? The system clock is still showing the correct date and time and my region of USA/Arcade was intact.

I'd be really greatly if someone could please advise, many thanks.
 
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