Aero Fighters 2 - won't let me fail?

mhkohne

Twinkle Star Sprite
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Sep 16, 2010
Posts
37
I just got an Aero Fighters 2 off EBay. It looks legit (I checked the board scans on http://mvs-scans.com ) It seems to play fine EXCEPT that when I get killed, the # of remaining lives doesn't seem to decrease! I played a level then half way through the second one realized something was fishy (I was dying a lot) so I let go of the controls and watched it for a while - I died 6 or 7 times without firing a shot and the # of spare planes in the upper left corner never diminished.

Does this have something to do with having my cabinet set for free play? Or might I be facing some other kind of error? The game's no fun if you can't lose!

Thanks for any hints.

EDIT: Note that before I ever put this cart into my Neo-Geo (I've got a 2 slot), I opened it up and cleaned the contacts with alcohol and de-oxit. There's no graphics glitches that I can see, and the gameplay otherwise seems fine.
 
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Gonemad

Neo Bubble Buster
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Jul 31, 2011
Posts
41
I just got an Aero Fighters 2 off EBay. It looks legit (I checked the board scans on http://mvs-scans.com ) It seems to play fine EXCEPT that when I get killed, the # of remaining lives doesn't seem to decrease! I played a level then half way through the second one realized something was fishy (I was dying a lot) so I let go of the controls and watched it for a while - I died 6 or 7 times without firing a shot and the # of spare planes in the upper left corner never diminished.

Does this have something to do with having my cabinet set for free play? Or might I be facing some other kind of error? The game's no fun if you can't lose!

Thanks for any hints.

EDIT: Note that before I ever put this cart into my Neo-Geo (I've got a 2 slot), I opened it up and cleaned the contacts with alcohol and de-oxit. There's no graphics glitches that I can see, and the gameplay otherwise seems fine.

Even with it set to free play, my Aero Fighters will still run out of men and have to continue to keep playing. All my games are like this on free play. I haven't checked the dip switches to see if there is any other settings that could affect this.
 

Tyranix95

Chang's Grocer
Joined
Jun 30, 2010
Posts
4,593
I have an MV-2F and an AERO FIGHTERS 2 MVS cart.

And when I set DIP#7 to Free Play and play the game, the number of planes (extra lives) decreases each time I hit something (crash, burn, die, whatever). Even, when I set DIP#7 to Pay-Per-Play and play the game, the number of planes (extra lives) decreases each time I hit something. So, yeah, your cart is acting :loco:.

Not sure why though.
 
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Xian Xi

JammaNationX,
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Dec 1, 2005
Posts
27,694
Clear your backup ram via hard dip 1 in the hardware test menu.
 

SNKorSWM

So Many Posts
No Time
For Games.
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Even though you can set the number of lives up to 99, the onscreen indicator can only show up to 5 or so and won't decrease unless you drop down to 4 or less. So go into the softdips and check whether it's set at some abnormally high number.
 

Neo Alec

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Posts
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If a cart isn't connecting perfectly in the slots the first time you boot it then it can cause all kinds of weird settings in the soft dips menu. That's why resetting the backup ram is the first thing you should try if a game is acting funny. Just don't have a non-SNK memory card in the slot when you reset or you'll probably erase the card too.
 

mhkohne

Twinkle Star Sprite
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Sep 16, 2010
Posts
37
OK, I've played around and there's definitely something up with the backup memory. It's a 2-slot board, and every time I go into the 'soft dip' menu, I see garbage for both slots, and then the thing resets, even if I don't have any carts in.
I've removed my memory card, no help.
I've gone into hardware test and cycled through to the 'reset backup memory' screen, then I hit ABC all at once. It doesn't say anything, but it flips to the next test screen. Once that's done, I power cycle and I see the same thing.
I've tried all these steps both with carts in and with no carts in.

Is this a sign of something wrong with the backup ram? If so, has someone got schematics for this board? Thanks!

Oh duh. Is this a possible symptom of the battery having gone? I replaced it a while ago, but I didn't have the best parts lying around. Could a bad battery cause this? Because that would at least be easy to fix, I think...
 
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Razoola

Divine Hand of the UniBIOS,
Staff member
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Nov 12, 2002
Posts
4,632
If you have a unibios do not go straight into the softdip settings after resetting the backupRAM. Allow the games to cycle once, then go into the games softdips and see if the curruption is still there.
 

mhkohne

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Joined
Sep 16, 2010
Posts
37
Sadly I don't have a Unibios (I keep thinking I'll get it...). I think I'll get the Unibios ordered and also replace the battery again. If the battery doesn't fix anything, then having the Unibios should help with the debug.
 

Neo Alec

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The battery is probably good, because it wouldn't be saving the garbage if it didn't work. It sounds like you're not resetting it right, or it's so messed up it won't allow you to. You can also try putting in many carts and letting it save the settings for those games until it finally clears out the data for Aero Fighters 2.
 
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mhkohne

Twinkle Star Sprite
Joined
Sep 16, 2010
Posts
37
The battery is probably good, because it wouldn't be saving the garbage if it didn't work. It sounds like you're not resetting it right, or it's so messed up it won't allow you to. You can also try putting in many carts and letting it save the settings for those games until it finally clears out the data for Aero Fighters 2.

Thanks. I'm going with the 'so messed up it won't let me' as my present idea. I've only got a couple of carts, but when I re-did the battery I used an external battery pack (it's the only nicad I had handy), and I put a connector on it, so it's really simple to just disconnect the battery and see what it does. That way at least I'm getting NEW garbage, instead of the same old garbage. I've also ordered the Uni-BIOS, for it's superior debug capabilities.

Thanks for all the help!
 

mhkohne

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Joined
Sep 16, 2010
Posts
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Thanks. I'm going with the 'so messed up it won't let me' as my present idea. I've only got a couple of carts, but when I re-did the battery I used an external battery pack (it's the only nicad I had handy), and I put a connector on it, so it's really simple to just disconnect the battery and see what it does. That way at least I'm getting NEW garbage, instead of the same old garbage. I've also ordered the Uni-BIOS, for it's superior debug capabilities.

Thanks for all the help!

Uh-oh. I pulled the battery for a while, and now I'm getting a backup ram error (address 00D00000 write 5555, read 55AE). I've had a look at the power supplied and +5 seems to be at 4.95 or so, while +12 is at 11.6. Can the backup ram error be caused by the missing battery? Or do I just have bad backup rams?
 

Xian Xi

JammaNationX,
Joined
Dec 1, 2005
Posts
27,694
Its either broken/corroded traces or your backup ram is bad. With the symptoms you've had maybe its the ram itself. Either way, send it out for repairs.
 

Tyranix95

Chang's Grocer
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Jun 30, 2010
Posts
4,593
XX is correct: looks like a board problem.

When I remove the battery on my MV-2F and boot the board with the AF2 cart in it, the game plays. And when I crash into something, the number of planes decreases, by one, as expected.

And, when I remove the battery on my MV-2F and boot the board without the AF2 cart in it, the board boots to a crosshatch screen. And, setting DIP#1 SW either way does not allow me to enter the service menu.

In any event, I'm not getting a backup ram error.

Hope this info helps.
 
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Neo Alec

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Removing the battery for a while should have cleared the memory and fixed the problem. So it's either something wrong with the games you're using, or more likely the board.
 

mhkohne

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Thank you all for your help - now that I know it's the RAMS, I have something to look at. I'll get the board out today or tonight and see if there's any residual trace damage from the original battery. If not, I'll get some RAMs in here and swap them out. Thanks!
 

mhkohne

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Sep 16, 2010
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Last follow-up: I got the board out of my cab and started probing on the bench. After checking all the diodes and transistors around the battery circuit, I started tracing where the battery power goes (the backup rams). No problems detected.

Looking at the MVS-1 schematic (the only one I could find anywhere on line), the system uses 2 ram chips, each 8 bits wide, one for upper, one for lower. Since the error message indicated that only one of them was bad, I wanted to figure out which one it was (so I didn't have to replace a good chip). I did this by tracing back to the 74HC32 that sources the write signals (BWU and BWL). Using a DMM, I verified that pin 27 on the one RAM chip connected to pin 8 on the HC32, but when I tried to prove that pin 27 on the other chip connected to pin 6 on HC32, it acted as if it wasn't connected.

I examined the board, trying to follow the traces and found that the trace from pin 6 goes on the bottom of the board to a via, where to jumps to the top of the board and goes to pin 27 on one of the RAMs. Further probing showed that pin 6 of the HC32 was NOT connected to the via, even though I could see the trace! Closer examination with a magnifier (and use of alcohol to remove residue from the rubber pad that was on there) finally located a slight nick in the trace, which apparently was enough to disconnect it.

I ran a wire from pin 6 of the HC32 to the via, and I was now able to prove that pin 6 ran to pin 27 of the appropriate RAM.

I suspect that the trace was damaged during previous repairs, and has been intermittent. For some reason it recently decided to give up the ghost altogether. This board had obviously been repaired before, multiple times. There was evidence of swapping of one of the custom chips (nicely done, if there wasn't a little left-over flux I'm not sure I'd have been able to tell), and the headphone jacks & volume controls had big blobs of solder on them, indicating replacement by someone less skilled (or perhaps lacking a proper iron). I cleaned up the volume related stuff just because it looked nasty, and I also removed the 470 ohm resistor and replaced the remote nicad battery pack that I had been using with a coin-cell holder on the board.

After all of that, the thing fired right up, Aero Fighters 2 worked great, as did the other game I keep in there, Bust-A-Move Again.

Definite points to the SNK engineers for making the board not impossible to work on.
Definite negative points to the SNK engineers for not putting individual chip designators on the board. It makes it hard to talk about it.

Once again, thanks for all your help.

EDIT: full log of the whole repair http://www.kohne.org/mike'sprojects/fixing-a-neo-geo-mvs-2-slot-board-backup-memory-error
 
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