MVS2 -01 graphics issues (probably multiple)

[Valsimot]

Hi all,

I picked up a 2 slot (MVS2 -01) a while back without a leaky battery but with an exploded ceramic cap: https://www.neo-geo.com/forums/index.php?threads/blue-ceramic-bypass-capacitor-spec.269550/

Starting a new thread to keep issues logically separated.

So at the end of the prior thread (cap found and replaced) I powered on to a blue/cyan screen with the original bios. Swapping for the unibios gave me a black screen (disclaimer I may have not pushed the unibios down enough here). Tried reseting Backup RAM content with the dips, no change.

Searching the forum I found @Xian Xi comment about pushing down on the Neo-D0. After a bunch of restarts, pushing on the D0, and swapping the bios/unibios I got the following error:

Yeah, that's helpfull
Probably says (lower) video ram error. Since pushing D0 got me to here, there is probably a bad contact on one or more of the D0 pins. They look ok to me, but will reflow them later:


Moving on, I put the unibios in (all the way this time) and set dip1 for crosshatch:

Beautiful. Seriously happy with the progress.
Ok, so turning off dip1 and inserting Metal Slug 1:


Yeah, it's got some graphics issues. The title and insert coin text appear, but never the game demo.
I found some suspicious/scratched lines on the PCB, but everything tests good.

I guess new lower video ram is needed, but why is everything blocky?

Any help appreciated.

 

[BIG BEAR]

For starters check your zmc2
BB

 

[ack]

I would check the LSPC-A0 for loose pins.

​

 

[Valsimot]

Thanks @BIG BEAR , @ack .
I had issues with D0 again today, so I reflowed it. Seems stable now.

I reflowed LSPC-A0 and ZMC2 as well. LSPC was a pain in the a$$, would love to never do that again
I now see more of the screen, also Metal Slug now has audio (Bubble Bobble did from the start). Slot 1 has worse video than slot 2 for some reason.

Slot 1 Metal Slug


Slot 2 Metal Slug


No cart Backup Ram error is new


So it looks like upper backup and lower video ram are shot.

This trace out of ZMC2 (above C) is super suspect, but passes continuity tests


As of right now I need to order two CXK58256MM-12L, or does this board use "fast video ram"?
Also a fiberglass pen, some 1 and 2mm enamel wire to fix any traces, probably a cap kit for the audio section too.

Anything else I should add to my basket?

 

[Valsimot]

Me, the genius, looks at board: fast ram CXK5814P-35L soldered to the video ram spot

 

[BIG BEAR]

Yooow dood..check your NEO-EO chip and or connections at location 7.5 H
This is the large 2 slot,correct?
BB

 

[Valsimot]

Hi @BIG BEAR , it's this board: https://github.com/jwestfall69/neogeo-diag-bios/blob/master/docs/ram_locations/mv2.md it does look bigger than the MV2F model.

I'll take a look at NEO-E0.
Is there a diagram somewhere that shows those location numbers (7.5H)?

Thanks

 

[BIG BEAR]

Hi @BIG BEAR , it's this board: https://github.com/jwestfall69/neogeo-diag-bios/blob/master/docs/ram_locations/mv2.md it does look bigger than the MV2F model.

I'll take a look at NEO-E0.
Is there a diagram somewhere that shows those location numbers (7.5H)?

Thanks

That's it. You follow the location from the numbers on top of the edge of your PCB and the letters on the right edge of the PCB. The NEO-EO chip I am referring to is right near the arrow in front of cartridge slot 1
BB

 

[Valsimot]

Ok, back on this thing over the last two weeks.
Had more ramndom graphics glitches appearing, resolved by reflowing the 32k video rams.

The blockyness should be caused by a breakage of the S rom lines described here: https://wiki.neogeodev.org/index.php?title=Graphic_glitches but I'm havibg trouble tracing the signal path... I made it from SFix to E0, but don't understand where to go from there. I think this is "2 rows duplicated" issue. Anyone have a schematic for the 2 slot? It would make tracing lines soooo much easier as the above doc was written for a single slot board with less chips in the path.

I tried to at least resolve the backup ram error by replacing the lower ram, but now I can't get it to load a game anymore, even with unibios. Trying to flush the backup ram makes the screen go black and then won't boot for a while (very weird). Errors flip between 5550 and 5507. Not even the crosshatch shows anymore , just this screen




Original Sony CXK58265MM vs new Infineon CY62256NLL-55SNXI backup ram:



Thanks.

 

[BIG BEAR]

Remove your replacement ram and reinstall the original one.
BB

 

[Valsimot]

Dang, was afraid you'd say that.
I got 2 more new ones, should I try them or write them off as incompatible?
The specs look good and they are new from a reputable source (TME .com).

Doing this with a standard soldering iron, so will need time to work up the nerve to do this again. Should really look into hot air or hot plates going forward.

 

[BIG BEAR]

Hot air it off,clean the contacts with solder wick and liquid flux then replace with the original chip.
Your backup ram problem probably lies with one or some of the components between the battery and backup ram.
The battery usually leaks on to those components wreaking havoc.
BB

 

[Valsimot]

I don't have a hot air gun, just a regular iron. Making replacing the ram a proper pain...

This model has the battery farthest away from everything, and I've checked all the nearby traces, they're all good...
Here's a pic of the battery spot top and bottom:


The underside has nothing but a power trace.

I just rechecked the 2 closest traces, going from pins 79 and 80 on ZMC2, all the way to PRO-C0 pins 13 and 14. They are good (about 1 ohm), it's got to be something else.

 

[Neo Alec]

If it's removal you're worried about, ChipQuik works.