MV1-C Slowdowns

[glac81]

Hello all,

I have got one MV1C board from Aliexpress and it appeared to be working fine.
Then I have made a mod to install unibios (had to get the OE signal from the neo-dcr because of a lost pad removing the original bios).
Everything seemed fine until I have paired it with Super Sidekicks 3. The menus are all ok until I have got to a match. If the ball is in the "top" of the field the game seems fine. When it is near the bottom the game gets very sluggish. Tried the same game with my other MV1C and the game flows normally. Tried to use the original MV1C BIOS archive and the slowdowns persist. Super sidekicks 2 and Ultimate 11 are even worse and gets to the point to be difficult to control de player.
The Neo Diagnosis gives ok for all the standard tests.
All the main chips seems original. The board is not pristine, but seems alright.
What can be the problem? CPU? GPU? RAM speed problems? Crystal?
I have searched for similar problems and haven't been able to find it yet.
I can make some videos to show the slowdowns. I know that there are games prone to this (MS2, aero fighters, strikers 1945, etc.), but the soccer games are not the ones reported. So weird...

Any ideas?

Thanks for the help in advance.

Glac.

 

[BIG BEAR]

A starting point would be the 24mhz crystal.
BB

 

[glac81]

A starting point would be the 24mhz crystal.
BB

Any 24 MHz oscillator with two terminals will suffice or is there a special part number needed?

 

[BIG BEAR]

Any 24 MHz oscillator with two terminals will suffice or is there a special part number needed?

No special part numbers.
BB

 

[glac81]

A starting point would be the 24mhz crystal.
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Just to clarify, can a crystal deviate in such a way that the board stays working but gets slowdowns when cpu is more loaded? What chip does the 12 Mhz generation on MV1C?

 

[glac81]

Just replaced with a crystal from a working mv1c that I have. The slowdowns continue. The crystal is clear. What can I try next?

 

[BIG BEAR]

Just replaced with a crystal from a working mv1c that I have. The slowdowns continue. The crystal is clear. What can I try next?

You don't have any missing components on this mobo,do you?
Check carefully if you haven't especially around the video ram.
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[glac81]

You don't have any missing components on this mobo,do you?
Check carefully if you haven't especially around the video ram.
BB

I will put side by side with the other one and compare.

 

[glac81]

You don't have any missing components on this mobo,do you?
Check carefully if you haven't especially around the video ram.
BB

Double checked and the components are all there. After some time with SS3 running the demo play, the board went into an error handling (!!). Slowdown is still there. Can a dirty cartridge slot cause this kind of behaviour? Seems pretty clean to me, but I can try to spray some contact cleaner to see if this can help.

 

[DaisyAge]

Have you tested any other games or at least made sure that SS3 is legit and not a bootleg?
Edit: Nvm too high, didn't read it all lol.

 

[glac81]

Have you tested any other games or at least made sure that SS3 is legit and not a bootleg?
Edit: Nvm too high, didn't read it all lol.

I will open the cartridge and verify it. The main point of the flaw is that this same cartridge works without slowdowns on two other mv1c that I have.

 

[BIG BEAR]

I will open the cartridge and verify it. The main point of the flaw is that this same cartridge works without slowdowns on two other mv1c that I have.

You stated that that the board goes into an error handling.Are you using a uni-bios with this problem unit?
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[glac81]

You stated that that the board goes into an error handling.Are you using a uni-bios with this problem unit?

I have made the mod to use Neobiosmasta. I have tested with unibios 4.0, unibios 3.0 and the sp45 original mv1c bios (from neogeo.zip). The slowdown occurs with all these bios.
The error was shown with unibios 4.0 in the socket.
Used the Neo Diagnostic bios also. The board has passed all the default tests.

 

[glac81]

I am willing to give up on this pcb as I saw that other member is having problems with Aliexpress boards. May try to salvage the good components (cpu seems ok for instance) and discard this pcb for good.

 

[BIG BEAR]

Did you inspect the

I am willing to give up on this pcb as I saw that other member is having problems with Aliexpress boards. May try to salvage the good components (cpu seems ok for instance) and discard this pcb for good.

Did you inspect the traces to the GRZ?
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[glac81]

Did you inspect the

Did you inspect the traces to the GRZ?
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The traces to GRZ seem alright. The solder joints of its terminals not so much. Is there a grz pinout somewhere for me to test the continuity?

 

[DaisyAge]

NeoGeo Development Wiki

wiki.neogeodev.org

This site should have what you're looking for, if not it's pinned out in this forum post:

Anyone got a pinout for the Neo-GRZ?

Trying to repair an MV1C with lines in the C rom data.

www.neo-geo.com