Help me fix the AES I just broke...

[GeorgeSpinner]

Title says the predicament I'm in...

I have a 1st version Neo Geo AES Gold system that my brother purchased new in 1991.

I was going to do an RGB bypass mod on it because he has always been unhappy with the RGB output of his AES.

While I was in there, I decided to install the unibios because he's always wanted it. This is where I started messing up.

I am pretty good at soldering. I am very bad an desoldering. The cheap tool I was using to desolder broke halfway though desoldering the BIOS (NEO-EP0).

I did the rest using desolder braid. I did ok until pin 30. pin 30 was hopelessly stuck and I coudn't get it out. Several traces run under pin 30 and I went and tore through them.

I need to remember I suck at desoldering.

After causing much damage, I got pin 30 out and installed the socket/unibios 4.0.

I turned on the AES just to see what would happen and it wasn't good. a signal that wouldn't sync and a checkerboard/color pattern.

I repaired the traces using wire and tried again. Same thing. That surprised me. I expected some difference.

I don't have pinouts for this exact board, so I used the pinout below (courtest of http://www.jamma-nation-x.com/jammax/tutorials.html):

I tested all the connections that I could. This AES does not have NEO-E0, NEO-G0 or LSPC2.

I was able to test connectivity to the 68000-12, 43256, and HC259.

Everything was fine except for pin 21. Pin 21 had significant resistance between it and the 68000-12 and 43256. Connection to HC259 was fine.

I don't know if this is normal, because the pinout above is not for the revision of the AES I'm working on.

This is what I get when I turn it on:

This is what the board looked like when I was done installing the socket (I'm so embarassed):

This is where I think the broken traces are supposed to go:

Again, the symptoms are EXACTLY the same with or without the traces broken.

Does any of this mean anything to anyone? Does it look like I identified the correct repairs?

Does anyone know anything else I can check? I only have a multimeter. no logic probe or oscilliscope.

Thanks.

 

[DeWitt]

Hi,
i'm really sorry that happens! i hope you get it working!

since i am really bad at desoldering too, i cut each pin of the chip i like to remove and remove pin after pin. yes this works only for chips you dont like to keep or are defect. but i dont destroy anything because it's much easier! i hope this tip helps for the future.

i'm sorry i can't help you with your actual problem. i wish your good luck!

 

[GeorgeSpinner]

Hi,
i'm really sorry that happens! i hope you get it working!

since i am really bad at desoldering too, i cut each pin of the chip i like to remove and remove pin after pin. yes this works only for chips you dont like to keep or are defect. but i dont destroy anything because it's much easier! i hope this tip helps for the future.

i'm sorry i can't help you with your actual problem. i wish your good luck!

Thanks.
I had this stupid idea in my head that I wanted the original chip to be in good shape for some reason.

 

[GeorgeSpinner]

I believe I have fixed my brother's AES.

I purchased a Japanese AES to replace his USA model. This way if it was never fixed, for some reason, he'd still have access to his library of games.

The Japanese AES was a 3-6 model. I did the unibios (piggyback with socket) and RGB bypass on it. Everything came out great.

From doing the Japanese AES I learned that the AES has no sync until the bios kicks in. My brother's AES was in this state and the bios was not kicking in. That eliminated the potential issue with the video that I originally referenced. So, at least it was 1 less issue to worry about.

I found an old post on neo-geo.com that detailed a pretty similar issue to what I was going through and it contained the detailed pinout for the original AES.

With this new information I was able to determine that I had to patch pin 21 of the unibios to pin 10 of the 43256, in addition to the patching I originally outlined.

I also had to straighten out the broken traces and make sure that none were touching each other since they were still connected on one end.

After doing all that, I got unibios to load!

Of course, I figured this out after purchasing a replacement AES. That's my fault, but I don't believe I would have fixed it otherwise. That's just how my life works. I'll either sell the Japanese AES or keep it for a while (forever?).

 

[yosai]

Even relatively simple jobs can go south without the correct tools. Good that you got it working though.

 

[GeorgeSpinner]

Even relatively simple jobs can go south without the correct tools. Good that you got it working though.

Yes; tools make all the difference. The tool broke in the middle of the job but I didn't know it.

I should have stopped working and tried to figure out why it stopped it working. I'm not that experienced with the desoldering tool and had never encountered any issues in my limited experience. I didn't realize that what I was encountering wasn't normal, sometimes.

I've purchased a better model and have been working on CPS1 boards that need new Z80 CPU. I've successfully removed 2 of them this week and will be putting the new chips in next week.

While troubleshooting, I desoldered the socket I installed in the AES and didn't do any further damage.

It was a learning experience. While I'm not glad it happened, I'm thankful for the knowledge and experience I've gained.