AES Blue SCREEN, all diagnostic tests pass.

[retrofletch]

Spent all day with this and got nowhere so now im asking for a bit of help on where to look next

Board is NEO-AES3-6 powered with 10v dc center negative.

No matter what cartridge i put in i get only blue screen ( system OK ) but no game will load, no sound.

I believe its possible that it broke because cartridge was plugged in when console was turned on if that helps?

I have tried following.
Unibios - gives me white screen, can not access any menues or diagnostics.
Diagnostic rom 0.19 - all tests pass, with m1 rom cartridge and doing z80 tests it gives no audible beeps so ALL OK, if i dont run z80 tests i get beeps so i know sound generation works.
Also i get all the text and menues with diagnostic rom so i also know video out works to some degree, controller inputs work.
i have tried also replacing the z80 but it made no difference, traced out all connections between z80 and c1, d0 chips, seems OK.

So basicly, it will pass system check "blue screen", pass all tests in diagnostics, i do get audio and video out during diangostics but no cartridge works ( except for the m1 rom char board used during diagnostics, that works).

I really dont know where to look next.

Ive checked the obvious, pins in cartridge slots, solder joints, cant see any bad traces either but maybe its hidden, and like ive said, i have tried about 6 different cartridges so i dont think its bad contacts.

Any ideas?

 

[Neo Alec]

Have you tried another power supply?

 

[retrofletch]

Have you tried another power supply?

No, are these systems picky with the supply? It's my first time working on a Aes. The psu is new and I've measured 5v at the chips so would assume it's good

 

[Neo Alec]

The 5v systems need to be given 5v. But since yours isn't 5v, any 8-12v center negative supply with the right sized barrel could work.

It's worth a try, since the Unibios won't boot, and you need at least that to tell if it's seeing the cart in the slot.

 

[retrofletch]

The 5v systems need to be given 5v. But since yours isn't 5v, any 8-12v center negative supply with the right sized barrel could work.

It's worth a try, since the Unibios won't boot, and you need at least that to tell if it's seeing the cart in the slot.

Tried a different power supply, no change, still white screen
i do still think i messed up something when i put cartridge in while console is on so now it dosnt recognize the cartridges because of that.

 

[Neo Alec]

When did the system last work? Did it work before putting a game in while the system was powered? I doubt that would permanently break something, but I suppose it's possible.

 

[maki]

The blue screen on the AES is the equivalent of the cross hatch screen on the MVS, usually caused by interrupted P Rom traces.

I'd start checking the traces for the P ROM.

@ack made a testing PCB for that, works in conjunction with the (new) DIAG BIOS

Neogeo diag bios crosshatch testing / custom prog board

I've been wanting to do this for a long while. One of the deficiencies of the neogeo diag bios is the inability to help when a motherboard boots to crosshatch. I decided to take a stab at creating a custom prog board to help with this situation. With it, its possible to verify P rom output...

www.arcade-projects.com