Save NG AES from the trash : green screen

dr.wily

n00b
Joined
May 24, 2005
Posts
31
Hello there!

A friend of mine give me his defect AES to repair. This NEOGEO initially had red screen that I fixed. There was a bad trace between D2 pin RAM chip pin 18 and 68k pin 54.

After this fix, I've got a green screen. I've checked all connections between RAM, HC259, LS273 and NEO-B1. All traces are safe.

This green screen displays with and without cartridge inserted. The motherboard is a NEO-AES3-6.

Now, I do not know where to search.

Can you help me to save this Neogeo from the dead? Thanks :drool:
 

daskrabs

Ace Ghost Pilot
10 Year Member
Joined
Aug 23, 2010
Posts
1,313
Green screen indicates color RAM error. I'd look there. If your traces are good, check for excessive heat on the chip(s). Or just replace them outright.
 

dr.wily

n00b
Joined
May 24, 2005
Posts
31
No excessive heat on the chips. I replaced original BIOS by Diagnosis BIOS but this new one display "nothing". Just a randomly colored screen with some glitch..
 

Xian Xi

JammaNationX,
15 Year Member
Joined
Dec 1, 2005
Posts
27,748
No excessive heat on the chips. I replaced original BIOS by Diagnosis BIOS but this new one display "nothing". Just a randomly colored screen with some glitch..

Look for broken traces with a bright light behind the board like the sun or whatnot.
 

dr.wily

n00b
Joined
May 24, 2005
Posts
31
Color RAM replaced... same green screen. I have almost tested all traces and found only 1 defect (wram <-> 68k)
- Unibios gives a blue screen with a game or not.
- Diagnosis BIOS gives glitched screen (soft reset works).

Any idea ?
 

dr.wily

n00b
Joined
May 24, 2005
Posts
31
Some news :

Found 2 bads traces between BIOS and NEO-G0.
Now I have a blue screen. Unfortunatly problem is not fixed.

There is 2 behaviour :

- game boot with glitched graphics, I have only some coloured blocks. Sound works.
- game boot with correct graphics, howerver there is no FIX layer. No text at all, no glitch just sprite+background whithout text. Sound is OK.

I have traced FIXD0 - FIXD7 as apparently these are related to S-ROM, I tested the continuity from the cart all the way to the NEO-B1 chip and it seems fine. I tested with UNIBIOS and Diag BIOS.

For the UNIBIOS the text underneath the Neo Geo logo on bootup does't show up. There is only Neo Geo logo. I have used the Neo Geo diagnostics bios but I can't see any text, just garbled screen. I have the UniBios as well, however these glitches also mean that I cannot see the UniBios text under the Neo Geo logo on bootup, and also I see no text when entering the UniBios menu by holding A+B+C.

Maybe there again a bad trace somewhere, but I tested nearly all connection between major component. My knowledge pretty much runs out there, if you have some tips to help, your welcome. ;)

EDIT :

Examples pics take from the console :

- NEO.GEO logo no SNK logo or 330... text
- ingame no points, energy bar...
- top players no text at all.
 
Last edited:

dr.wily

n00b
Joined
May 24, 2005
Posts
31
OK this NEO.GEO is alive ! There is several issue that give this green screen.

Fisrt, red screen :
- broken line between 68k pin 54 and WRAM pin 19

After this fix I have a green screen, but there is no problem with palette/color RAM, but found :

- broken traces between BIOS (SP1) pin 18 and 19 (line D1 & D0) and 68k pins 4 & 5.

After this fix, the NEO.GEO gives a blue screen and is able to boot game. However there is no fix layer (look at the pics in my previous post). Searching again for another bad trace... FIX layer is related to FIXD, PCK1, PCK2, 2H1 and 1MB lines. And the winner (or loser, the choice is yours) is :

- 1MB. Found a tiny broken trace between NEO-B1 pin 84 and a chip very close to NEO-B1.

You can use this post as reference if you have the same issue. Thanks for your input.
 

fufen

n00b
Joined
Feb 1, 2014
Posts
12
Hello, I have similar error, yellow screen with diagnostic bios and a dirty screen with unibios.
It is curious, if I insert a game with unibios, console try to run the game but obviously, the game does not restart doing it in bucle.
O have checked the traces between bios, vrams and 68k, but I have continuity in all traces.
Any idea?
 
Top