MVS Super Sidekicks 3 - Graphical glitch

[RomiBraman]

Hi guys,

I just got my hands on a mvs Super Sidekicks 3 and I can't get it to work correctly.

I have MAJOR graphical glitches on both my Neo Geos. The problem starts from the very beginning. Even the Line of the UniBios appeared doubled.

and when the Neo Geo Logo appears, the bottom part is completely scrambled. The PCM works flawlessly though.


What I've tried so far :
- Complete reflow
- Thorough cleaning.

Any ideas ?

Thanks,

Romi

 

[BIG BEAR]

Whatever the problem is lies with the CHA pcb.Jumpers not set correctly(not likely),a bad trace(s),a bad S1 chip or Bad C ROM(s)
BB

 

[RomiBraman]

Whatever the problem is lies with the CHA pcb.Jumpers not set correctly(not likely),a bad trace(s),a bad S1 chip or Bad C ROM(s)
BB

Thanks it gives me a starting point.

Any idea how I could test the S1?

For the Cs I guess I could use an oscilloscope to test the signal on the outputs...

 

[ack]

Are the Fix graphics corrupt too? If thats the case I would suspect an address line issue.

I would check for continuity between the CHA board edge and the NEO-273 chip on the CHA board, and then from the NEO-273 to the address pins of C/S roms.

https://wiki.neogeodev.org/index.php?title=MVS_cartridge_pinout
https://wiki.neogeodev.org/index.php?title=NEO-273

 

[RomiBraman]

OK I will test

 

[RomiBraman]

I would check for continuity between the CHA board edge and the NEO-273 chip on the CHA board, and then from the NEO-273 to the address pins of C/S roms.

Ok so I've checked my continuity and everything seems fine (thanks for the links they were great help).

2 things :
- The boards are really in good shape. Looks new, no corrosion at all so, broken trace feels unlikely

_ One thing I haven't noticed before is that with the cartridge in, even the Unibios menu is glitched, Text appears 2 times, and some text not at all (impossible to do the CRC check for example, as the text is unreadable).

I try on my AES with a converter and the result is exactly the same.

Could a bad C ROM caused even the Uni Bios menu to malfunction ???

Thanks again for your help,

Romi

 

[ack]

Unibios should be using the S1 rom from the cart. If no cart is inserted it will use the SM1 from on the motherboard. Since both FIXED (S1) and sprite data (C) is bad it makes me think something is up with the address lines to them. If continuity is good, my best guess is there is something wrong with the NEO-273 as its handles address lines for both the S1 and C roms.

 

[RomiBraman]

Yep that was it. I swapped the Neo273 with a Puzzle Bobble. And it did the trick.
The thing is I love my puzzle bobble so I need to find a Neo 273 somewhere. Not an easy task.
Thanks again for your help.