SNK Neo Geo AES (Rev 3-3): Sprite Fault, Broken Traces & Recap

A bit later in 2021 I got my hands on an AES, so what I though when I got the NGCD turned out to be wrong. I did manage to get into the AES too. Of course this means that I had to recap it. As it turns out, I'd also be making a few functional fixes. #retrogaming #neogeo

I used a console5 cap kit and it turned out to have incorrectly sized caps for the video area, which made it look like a bit of a mushroom cloud. This was fixed later, meanwhile, I applied a fix to the video section (from the kit), the 68 Ohm resistors were replaced with 75 Ohm.

Finished with the FirebrandX audio fixes (AES revs 3-3/3-4): SNK deleted audio filter caps to save pennies, leaving 60Hz buzz. Reinstalled the missing ceramics + 470uF on the 2066D and swapped the reversed left-channel polyester caps. Dead silent and audio channels matched. 🎧

Also got myself a NEOSD Pro along the way and tested the console with Metal Slug X. The NEOSD Pro would turn out to need a fix itself later on, due to a production run defect.

I went through my archive again and it turns out I was wrong about this one, this is actually, the second AES I got my hands on. This one required some repairs to get working properly, so let's check those out. It presented with problems drawing sprites correctly.

In we go, thinking it might be related to video RAM. Socketed the chips so I could try new ones, as this seems to be reported as a common failure, alas, that would not be the fix for me. While in there, I remember I also took the chance to install a Unibios 4.0 chip.

This issue puzzled me for quite a while, I was much greener back then and felt I didn't really know what else to check. As can be seen in a previous shot, someone had already fixed a trace in the cartridge slot, so I discounted that. Ignoring that area turned out a mistake.

As I delved deeper a new fault developed. I reflowed ICs with suspect looking joints, the console started booting to a green debug screen and not loading games. A trace between the work RAM ICs lost connection. I fixed it and replaced the cart connector with the smashed pin.

After considering what I had seen in the cartridge connector and what happened to the work RAM. I started wondering what else could have had a similar fate. I eventually trace the original fault to a broken connection between the LCPS2 and the VRAM.

So, after fixing that, I had a fully working second, cheaper, Neo Geo AES, which I meant to sell but never did.