Graphical issues

[Matt2797]

Just got a new Neo geo aes (board 3-5) and running into some issues with graphics. Initially I was getting pixelated images starting with the entire logo and in game. After cleaning the slots out I’m getting issues like the words “Neo-geo” look off and everything else looks fine. In game, when playing samurai showdown, the characters get pixelated at times during game (usually less pixelated on the edges and more when in the middle.) Ref is also always pixelated in background.

Guessing there’s a broken trace somewhere, any clue where to start? Including pics prior to cleaning cartridge slot. Neo-geo logo still looks the same, all the words now look fine.

?

 

[maki]

Is the Video RAM okay?
Do you have the DIAG Bios?

Maybe you can match your graphic glitch to the ones shown here:

Graphic glitches - NeoGeo Development Wiki

wiki.neogeodev.org

here is an overview over the signals and what problem they can cause if they are missing:

Signals - NeoGeo Development Wiki

wiki.neogeodev.org

most of the time it's a rotten trace, how does the PCB look?

 

[slugger_dan]

Yeah I second a good look at front/back of the board especially around the B1 and LSPC.

Neo-geo logo still looks the same, all the words now look fine.

Credit counters and most status bar graphics look ok too? Looks like a sprite pixel data problem. As a starting point there's a cart pinout with all the names here:

AES cartridge pinout - NeoGeo Development Wiki

wiki.neogeodev.org

Bit hard to tell from the photos but EVEN + 12M would get extra attention if I was looking at it. The other sprite pixel pins are H,LOAD,GAD,GBD and the DOT pins. Doubt it's the latter 3 in your case. They go to these on the board except for 12M (check NEO-D0 page for that). The graphics glitches page is great just needs a bit of extra AES info.

LSPC2-A2 - NeoGeo Development Wiki

wiki.neogeodev.org

NEO-B1 - NeoGeo Development Wiki

wiki.neogeodev.org

 

[Matt2797]

Yeah I second a good look at front/back of the board especially around the B1 and LSPC.

Credit counters and most status bar graphics look ok too? Looks like a sprite pixel data problem. As a starting point there's a cart pinout with all the names here:

AES cartridge pinout - NeoGeo Development Wiki

wiki.neogeodev.org

Bit hard to tell from the photos but EVEN + 12M would get extra attention if I was looking at it. The other sprite pixel pins are H,LOAD,GAD,GBD and the DOT pins. Doubt it's the latter 3 in your case. They go to these on the board except for 12M (check NEO-D0 page for that). The graphics glitches page is great just needs a bit of extra AES info.

LSPC2-A2 - NeoGeo Development Wiki

wiki.neogeodev.org

NEO-B1 - NeoGeo Development Wiki

wiki.neogeodev.org

Thanks for the replies, currently waiting on the diagnostic bios in the mail, so until then trying to see what I can find. On quick glance, didn’t notice any obvious breaks in the traces. I’ll take a look at all the mentioned places until the diagnostic bios arrive.

 

[ack]

The diag bios is unlikely to help in this situation. The corruption is in the stripe/fix data which the cpu doesnt have access to.

 

[maki]

If the Diag BIOS doesn't find any problems, check the connection of WE1-WE4 from the LSPC-A2 to the B1.

 

[Xian Xi]

Most likely cart slot to the Neo-B1, check continuity between CHA Board B3-B10 and Neo-B1 131-138.

 

[Matt2797]

Thanks for all the replies so far. I’ve so far, cleaned out the cartridge slot again and checked for broken traces around the board (waiting on new magnifier since eyes are getting too old).

So far continuity around b1 and lspc-a2 seems fine and no broken traces. Including a pic of the front and back of the motherboard in case someone sees something I’m missing.

Also including a couple more pics of the glitches. Ignore the coloring of the Neo-geo logo (it’s on a CRT and the color is correct), but as you can see the letters for Neo geo look off and everything else is sharp. With Samurai Showdown, you can see the character on the left is sharp the one on the right pulses between sharp and distorted like in the picture.

Appreciate all the suggestions so far.

 

[Xian Xi]

If you didn't do anything and now the SNK logo is being drawn correctly, I'm leaning towards a dirty cart slot/cart. Clean your cart slot with a piece of thick cardboard with contact cleaner(solvent free) and then clean your cart edges with a pink eraser.

 

[maki]

checking every trace of the cart slot isn't as much work as it sounds

Take a MM, find a GND point and attach the black probe of the MM to it.
With the red probe, test every single contact of the slot, if its not ground or happens to be low (test when turning it on can show if its high at any point in time), it must show a voltage, otherwise you have your culprit

 

[Matt2797]

If you didn't do anything and now the SNK logo is being drawn correctly, I'm leaning towards a dirty cart slot/cart. Clean your cart slot with a piece of thick cardboard with contact cleaner(solvent free) and then clean your cart edges with a pink eraser.

Thanks, tried cleaning the cartridge slot again, there was pretty much no dirt left. Started doing some more continuity testing, but ran out of time for today.

As reference, here’s a picture from my system on the same screen from the graphical glitches section. Not seeing anything there that seems to line up with this glitch.

 

[ack]

It looks like the issue might be the 'EVEN1' signal from the LSPC-A2 not making it to the NEO-ZMC2 chip on the CHA board.

I would check

LSPC-A2 PIN 110 <=> Cart slot (nearest the 68k cpu) A7

If the EVEN signal is messed up/missing you often see the effect where it looks like each column of pixels in the sprite are swapped.

 

[Matt2797]

It looks like the issue might be the 'EVEN1' signal from the LSPC-A2 not making it to the NEO-ZMC2 chip on the CHA board.

I would check

LSPC-A2 PIN 110 <=> Cart slot (nearest the 68k cpu) A7

If the EVEN signal is messed up/missing you often see the effect where it looks like each column of pixels in the sprite are swapped.

I think you got me on the right path, just checked and no continuity between those two. Haven’t found the break yet, but I’m guessing this is where it’s at. Thanks.

 

[Neo Alec]

Thanks, tried cleaning the cartridge slot again, there was pretty much no dirt left. Started doing some more continuity testing, but ran out of time for today.

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[Matt2797]

Thanks for the help, graphic issues are now gone (it was the even trace). Now have one last issue, for controller slot one, it is constantly pressing up, even if nothing is pressed on the controller (same controller works perfect on slot 2). So far I’ve tried cleaning the cartridge slot with contact cleaner and reflowing the solder to the port with no improvement. Any suggestions?

 

[BIG BEAR]

It looks like you need to replace one of the bus resistors..the resistor for UP may have died.
BB

 

[Matt2797]

It looks like you need to replace one of the bus resistors..the resistor for UP may have died.
BB

I take it it’s the arrays at either cr1 or cr2? If yes, any good places to get a replacement?

 

[BIG BEAR]

I take it it’s the arrays at either cr1 or cr2? If yes, any good places to get a replacement?

It would be the CR5. Where to get them? I salvage most of my parts off of designated parts boards...
drop me PM if you want a few from me...
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