Big Red cross hatch of death

wyo

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I recently picked up a non-working Big Red with an MV4 motherboard. The PSU was fried so I replaced it with Suzo Happ 80-0072-00. Now the system powers on, displays some blocky graphics for a second or two, then goes to the cross hatch screen of the hardware test mode. On the bright side, everything else seems to be working fine except for the motherboard. I've tried different games in different slots without success. I also cleaned the cartridge connectors and blew everything out with compressed air.

Noob alert! This is the first cabinet I've owned so I'm pretty clueless. My plan is to disconnect, remove, clean the MV4, and check for damage. I understand a leaking battery can cause issues like this so I will inspect it. Basically, I would greatly appreciate some basic step-by-step troubleshooting advice on how to proceed to get this thing up and running.

Side note: I found an unconnected cable inside the cab (see 2nd pic). It's probably irrelevant but I thought I'd mention it.

100_5433.JPG100_5435.JPG
 

RabbitTroop

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Four slots are very problematic boards. Looks like your cab is working fine, and luckily the only thing you may need to replace is that main board. Whether or not you keep it a four slot will be completely up to you. I've gone through several over the years and I'm still searching for a problem free one. Conversely, my original two slot is still going strong to this day.

So, what happened? Probably a leaking battery. At this point I can't imagine there are very many original Neo batteries that haven't started leaking. I'd pull that four slot out, take it apart and desolder the battery as soon as you can to stop further damage. If you get lucky and it's not the battery, there are several other issues that could cause a cross hatch screen. Basically, the Neo simply can't read your cart. That's why you're seeing that. It could be a bad cart slot, but if they're all doing that... probably not. It could be it just needs a good cleaning with electrical cleaner, but... again... you'd probably have seen something in one of the slots if that was the case. The act of simply taking it apart and putting it back together might help if one of the little connectors around the edge has gotten loose. Basically, taking it apart and seeing what you have will probably help.

After that, there are a few people here on the forums that can help diagnosis issues. If it's simply the battery ate a few traces from the board, you can wire them back up after cleaning the area. If it's a bad chip, you can go the route of repair, or just buying a new motherboard. Four slots sell in the $100-150 range, so you really need to look at this as a time vs skill vs cost basis and see what makes sense.
 

RabbitTroop

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Oh, and that extra cable looks like it would go to cabinet lighting or maybe for some other board that was in the cab previously. I see you have credit indicators on your control panel, and they're lit and it looks like the cabinet overall has all its lighting on. Actually sort of looks like a kick harness to me for a CPS system, but whatever... Basically, that's not needed for anything. Hell, even those big chunky looking connectors on the side in slots A and B are extraneous. They just feed the memory card slot ;) I never hook those up.
 
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wyo

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Big thanks to RabbitTroop for the replies! :)

Yeah, if this turns out to be a complex or expensive fix, I will probably end up just replacing the board with a more reliable model. Will all other MVS boards "plug n play" with the wiring harnesses, PSU, and other hardware in my cab?

I'm partway through the cleaning process. The board was/is pretty dirty and a ton more crap flew out of the cartridge slots. I just wanted to confirm the method of disassembling the 2 boards. Looks like there are 2 gold screws (one each on slots 1 and 2) and 4 smaller silver screws near the various board to board connectors around the edge. Do I just unscrew these and ease the boards apart?

Thanks again!

100_5446.JPG
 

mjs256

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Wow that is a nice looking cabinet! It looks like you have a memory card reader and everything.

The good news is that everything looking good with the crosshatch screen and diagnostic tests means the board is at least 90% working.

I agree that the first thing to look at is the battery on the lower board. See if there are signs of corrosion, greenish residue, or if the board looks "wet" in the area of the battery. If it still has the original battery (GS SAFT GF50-3S) then it is probably best to get rid of it as it is a ticking time bomb that may or may not have already gone off. It will run just fine with no battery (it just won't remember date, time, high scores, game settings, etc... after it is unplugged). I recently fixed and MV-4 like this that had this exact issue - would not read any games and was stuck doing crosshatch/diagnostics. The battery leakage had eaten one trace and after I patched the trace the board worked fine. If you find any signs of battery leak I recommend neutralizing the chemicals with a solution of baking soda and water (baking soda is good because it acts as a buffer for both acids and bases).

Next, make sure those cartridge slots are clean. I recommend the isopropyl/credit card/t-shirt method.

Next, check the voltage of the +5v line while it is running to see how if the power supply is keeping it up under load.

Sometimes MV-4s need just a little more juice - if your power supply is adjustable you can try increasing the voltage a bit, but don't go past 5.3 volts or so.

It is a good idea to replace those big 1000 microfarad capacitors on the top board.

If none of those work then try replacing the top board with a known working one (if you have access to one) - this will tell of the problem is in the top board or the bottom one.

From there you may need to use a logic probe for diagnosis.

Good Luck!
 

RabbitTroop

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Big thanks to RabbitTroop for the replies! :)

Yeah, if this turns out to be a complex or expensive fix, I will probably end up just replacing the board with a more reliable model. Will all other MVS boards "plug n play" with the wiring harnesses, PSU, and other hardware in my cab?

I'm partway through the cleaning process. The board was/is pretty dirty and a ton more crap flew out of the cartridge slots. I just wanted to confirm the method of disassembling the 2 boards. Looks like there are 2 gold screws (one each on slots 1 and 2) and 4 smaller silver screws near the various board to board connectors around the edge. Do I just unscrew these and ease the boards apart?

Thanks again!

View attachment 8478

Yep, around the edges you'll find some white connectors that keep the board together. Simply remove the screws you'll find holding these together, and then those two screws you'll find on the ends of the two cart slots and the board will pull apart. Just use a very little amount of force at each connector and they'll pop apart. If any side sticks, make sure you removed both screws from that connector ;) Once apart you can get a better look at what you're dealing with.
 

Xian Xi

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Dont fuck with rubbing alcohol, just wash the board with soap and water and remove the battery and socketed chips first. I usually use canned air to get the water out of the connectors and under the chips and then put it in the sun for about 2-3 hours. Make sure it's completely dry before powering on.
 

wyo

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Thanks to everyone for the helpful replies!

The top board is now much cleaner and the traces look fine. They also look good on the underside of the lower board. I'll check out the lower board and desolder the battery tomorrow and report back.

Cheers!

Nick
 

Terot

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Don't forget to post pictures of the under board, the higher the resolution the better chance you have of one of us seeing and issue.

Also, if you want to be able to save your high scores you can replace the battery with a wireless home phone battery (they are super cheap on amazon) or a watch battery (recomended if you do not leave the system on often).
 

wyo

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I got ambitious and decided to tackle this tonight.

Here is a before and after:

y134.jpg


v8wg.jpg


Looks pretty bad, lol! What a stupid place for a battery. Is this fixable?
 

ebinsugewa

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Check the traces around it for continuity with a multimeter. They don't look so hot.
 

RabbitTroop

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Yep, looks like that battery ate a few traces. Not too bad, though. The ones right under the battery look to be the worst. Probably need to run a few wires there, for sure. As was suggested, you'll need to check continuity using a multimeter. If you don't have one, RadioShack sells a cheap little gray multimeter that folds up for around $20. That will be a lifesaver working on the cab, as you can quickly check voltages and continuity with it. Definitely a nice go-to in this hobby. Honest opinion is it doesn't look too bad right now. Definitely a few wires to run to repair those traces that got eaten, but the damage is pretty small. I think you can fix it with a little work.
 

xsq

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be sure to neutralize the battery leakage. Vinegar should do the trick for Ni-Cd batteries... wash thoroughly after. If you're lucky there will only be a few traces damaged that you will need to bridge.

Best of luck fixing the board, that big red looks really nice otherwise.
 

shadowkn55

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I would try to wipe away any battery residue with a dry cloth then some rubbing alcohol first. Going straight to a base to neutralize the acid will cause a chemical reaction and potentially make the situation worse.
 

xsq

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good point. It seemed to me from the pictures that the spot had already been cleaned up a bit.
 

mjs256

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be sure to neutralize the battery leakage. Vinegar should do the trick for Ni-Cd batteries... wash thoroughly after. If you're lucky there will only be a few traces damaged that you will need to bridge.

Best of luck fixing the board, that big red looks really nice otherwise.

I do not think it is a good idea to use vinegar (aka acetic acid IIRC). I think the battery leakage contains hydroxide - a nasty base that is the primary ingredient of Drano. It is true that mixing a nasty base with a nasty acid yields pH-neutral water, but the proportions would have to be absolutely perfect. If there is any extra acid or extra base (even a little) then you would still have nasty chemicals eating the board, and I think acid eats metal more aggressively than bases do. You could use an excess of vinegar to wipe out the base, and then use an acid buffer to neutralize the excess acid. I would just use baking soda (aka sodium bicarbonate) because it neutralizes both acids and bases so you are covered either way.
 

xsq

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You could use an excess of vinegar to wipe out the base, and then use an acid buffer to neutralize the excess acid. I would just use baking soda (aka sodium bicarbonate) because it neutralizes both acids and bases so you are covered either way.
You're right. Off the bat I thought baking soda was a base too, but yeah, turn's out I'm an idiot and of course it's amphoteric...
 

wyo

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Hey guys,

Project currently on hold for a day or so. Thanks for the tips. I need to buy a multimeter and a more precise tip for my soldering iron. I have some appropriate wire so I'm good there. As I understand it, once bad traces are identified, I need to bypass them by soldering the wire from where the trace originates to the destination.
 

Terot

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As I understand it, once bad traces are identified, I need to bypass them by soldering the wire from where the trace originates to the destination.

Indeed, and don't worry with any of that "just bypass the bad section" crap. I solder a wire directly to the component the trace starts at and directly to the component at which the trace ends. I usually stick with 22 gauge although you can use thiner wire if you want.
 

wyo

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Update: Bought a GE digital multimeter from Walmart and found a new soldering iron tip. The wire I have on hand is 30AWG: http://amzn.com/B006C4ADFA. Sorry if this is a stupid question but when adding wire to repair a trace, do I leave the component leg attached to the PCB?
 

Cyberdemon

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Update: Bought a GE digital multimeter from Walmart and found a new soldering iron tip. The wire I have on hand is 30AWG: http://amzn.com/B006C4ADFA. Sorry if this is a stupid question but when adding wire to repair a trace, do I leave the component leg attached to the PCB?

Yes, leave the component leg attached to the PCB, and solder a wire from start to end of the trace. it should be working like new again!
 

wyo

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Identifying bad traces...


After I deciphered the code, this helped me quickly determine that the following traces are broken on CN10: A5, A6, B5 and B6. Those should be relatively easy to fix.

A7+ and A8+ seem OK but I didn't test them all yet.

These looked dodgy but they're OK:

B25 PRO-C0 (72)
B26 PRO-C0 (74)
B27 PRO-C0 (75)
B28 PRO-C0 (73)

However, I'm pretty sure the closest 4 traces located south west of the battery are also dead. These seem to lead from legs on chips F11 and G11 to P1 (the connector on the bottom edge of the board that looks like a cartridge connector. Can someone confirm this? If so, do I solder from the chip legs to the corresponding spots above the connector?

v8wg.jpg
 
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wyo

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Fixed CN10: A5, A6, B5 and B6

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