Blocky Metal Slug 4 graphics (original cart)

[bytestorm]

Yo!
Friend of mine asked me to check his ms4 cart out. Its really clean but gives blocky graphics. S rom seems ok, and sound + music works. But there is no intro, jumps straight into gameplay and it looks like this:

https://youtu.be/dC-BiCyPBoM

And unibios looks strange in the crc test menu.. but reports all ok? Anyone seen before?

I cleaned the cart, tested 2 different mobos.. still the same.

 

[GadgetUK]

Maybe bad solder point on C chips, or that neo CMC chip.

 

[aha2940]

The C roms seem to be problematic. I think either they are bad, or the decryption chip on the CHA board is bad. Desolder and test the ROMs and hope for the best.

Regards.

 

[GadgetUK]

What's that 3 pin device, is it a regulator?

 

[HeavyMachineGoob]

Yes, probably a 3.3v regulator.

The problem lies somewhere with the C ROMs or NEO-CMC chip. You could check for dry or cracked solder joints and do continuity tests with a multimeter. I've heard sometimes reflowing the NEO-CMC fixes this, but it's got tiny legs, not something for beginners.

 

[Xian Xi]

For Metal Slug 4, the PCBs were made too wide so when they are inserted into the slot they warp. You need to shave the ends about 1mm on each side for both boards. You can measure it yourself and see.

 

[Archdesigner03]

slug4 is currently affordable enough to be replace with a new copy. No point of spending the time to figure out what is wrong with it in my opinion.

 

[bytestorm]

Thanks for all the replies! I guess reflow in the joints doesn't hurt, even thou they look good under a microscope.
The CMC is also doable since I have a tip for these small ones and some flux.
Remove all C chips is a pain since they are soldered all that way throu the board but I guess that's the only choice.. :/
How does the CRC calculation work in UniBIOS? I mean, if the C roms would be bad, wouldn't the crc bankS fail?

Also, is there any proper flash+pcb adapter to replace these 64mb C maskrom with? Or should I go the heavy way and double 27c322 epromS?

I know that this is a cheap game and not even that good compared to ms3 or so but it's still neo geo.. man I want to atleast do my best to save it

Also, forgot to mention that the edges are filed already, I didn't know they did that but I reacted a bit cuz I thought they looked quite rough. I'll defenitly check it against another board in case they need more!

 

[Xian Xi]

Thanks for all the replies! I guess reflow in the joints doesn't hurt, even thou they look good under a microscope.
The CMC is also doable since I have a tip for these small ones and some flux.
Remove all C chips is a pain since they are soldered all that way throu the board but I guess that's the only choice.. :/
How does the CRC calculation work in UniBIOS? I mean, if the C roms would be bad, wouldn't the crc bankS fail?

Also, is there any proper flash+pcb adapter to replace these 64mb C maskrom with? Or should I go the heavy way and double 27c322 epromS?

I know that this is a cheap game and not even that good compared to ms3 or so but it's still neo geo.. man I want to atleast do my best to save it

Also, forgot to mention that the edges are filed already, I didn't know they did that but I reacted a bit cuz I thought they looked quite rough. I'll defenitly check it against another board in case they need more!

It doesn't look shaved but if they are then you need a mag glass to look at the pins on the CMC and the edge of a blade or dental pick to see if any pins are loose.

 

[bytestorm]

I admit it's not much but someone has been shaving the edges a bit. But maybe it's to little? I'll find a board and compare!

 

[bytestorm]

By the way, how to read these 64mb maskrom? Does these 64mb C roms use any known pinout? There is nothing written on the pcb and the chips only has 263-Cx mega enterprises written on them.. (1-6)

I checked all pins of the CMC with a dentist tool under the microscope and all seem soldered good, and doesn't move.
The size of the pcb also matches my other ones so I guess it's shaved enough :/... only option left if to dump all C roms in my advantech 48 uxp and compare in romcenter.

Thanks

 

[Xian Xi]

It's not so much the length but check how the pins line up. On the MS4 PCBs, one side has too much material between the edge and pin.

 

[Footix]

You can read them as 27c322 when you put a22 to gnd or vcc

 

[aha2940]

You can read them as 27c322 when you put a22 to gnd or vcc

I believe you read the first half (A22 to ground) first, then the second one (A22 to 5V) and then add the two files to get the complete rom.

Regards.

 

[fremen]

Hi dudes,

Take into account that you need to compare the C readings with a non decrypted rom set.

Saludos

 

[bytestorm]

It's not so much the length but check how the pins line up. On the MS4 PCBs, one side has too much material between the edge and pin.

Aaa..good point I'm on it!

 

[bytestorm]

Hi dudes,

Take into account that you need to compare the C readings with a non decrypted rom set.

Saludos

Yes sir! Thanks

 

[bytestorm]

I believe you read the first half (A22 to ground) first, then the second one (A22 to 5V) and then add the two files to get the complete rom.

Regards.

Nice info.. that'll sure come in handy!!