Help with my Aes. Got power now a new problem

Hey everyone, I need a little help here fixing my aes. I bought the broken one pictured in this thread: http://www.neo-geo.com/forums/showthread.php?t=170139.

The problem is that it does not power on, even with a bios chip in it. I am using a genesis power adapter to power it as I believe the system was one of those retrofitted to take a 9v power supply despite the serial saying use pro-pow2 only. I am thinking this way due to the brown board dangling around in those pictures and what someone one these forums said in regards to its presence.

Here's the weird thing: Before I put a bios chip in, it would power on (led would flash on then off) for a split second. Now after I put the chip in, regardless of if the socket is empty or not, it gets no power whatsoever. I've taken a multimeter to it and measured voltage across various places across the board and here is what I have found:

Power is going through the switch and into the brown board, but seems to be stopping somewhere there. No power to the chips at all.

When I measure voltage across the jack and brown board, it seems that power goes into it on the yellow wire, but something happens there and it does not return on the red wire, but I am not totally sure.

I am thinking that the A1442 on the board is the culprit, but I can't figure out what the thing is and what it does via google or otherwise. Anyone know?

Any help in this matter is greatly appreciated as I really want to play my neo!

Edit: Something must be terribly wrong, the meter reads 14.5 volts across the few components that get power, even though the power supply is only 9V???? I've tried two genesis adapters with the same results.

Lios said:

The problem is that it does not power on, even with a bios chip in it. I am using a genesis power adapter to power it as I believe the system was one of those retrofitted to take a 9v power supply despite the serial saying use pro-pow2 only. I am thinking this way due to the brown board dangling around in those pictures and what someone one these forums said in regards to its presence.

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And you're wrong. That Neo is a 3-3 revision that originally is supposed to work with a 9-12v PSU but this one has been modified (by SNK) to work with a 5v power supply (so the pro-pow2 indication is correct). You might have damaged the transistor on the daughterboard.

Ok thanks for the info. Man all these different revisions and mods throws me off as to know what kind of supply you need. I researched for hours and couldn't come to a definite conclusion.

So do you know how I might know if I damaged the transistor? Is there any way to test it? I am assuming the part in question is the A1442 green transistor on the daughter board, right? Thanks again for the help.

you need to get the correct psu and if it still doesn't work the green transistor is likely to be damaged (no 5v on the collector). Alternatively you could get rid of the 5v daughterboard and restore the original power input circuit (and use the 9v psu) as the cost of these parts is likely to be cheaper than the cost of a 5v power supply.

MKL, do you know what size the barrel jack is on the AES?

it's 2.1mm x 5.5mm.

Just a heads up as I was just looking at it. I am in possession of a 3-3 revision minus the daughterboard and it requires a 5v 3a supply.
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MKL said:

it's 2.1mm x 5.5mm.

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I think the PSU I use for my CMVS would work then. Is it positive tip polarity or does it matter with the AES?

https://www.jameco.com/webapp/wcs/s...toreId=10001&catalogId=10001&productId=319881

Edit, I just checked and the AES is negative tip polarity. You can always rewire the socket but it wont be pretty.

Xian Xi said:

Edit, I just checked and the AES is negative tip polarity. You can always rewire the socket but it wont be pretty.

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best would be to open the PSU (if it can be done) and reverse the wires internally.

Alright, so I went and bought a 5v 3 amp power supply, hacked the end to change the polarity to negative tip, put in a new power transistor, and put in a unibios chip, and it works, but with some problems. The sound is fine, but the games have a heck of a time starting (random illegal address errors at boot-up, graphics glitches in unibios menu, etc.) However the main issue is that everything except the text and a few other things have small black squares missing in them in a uniform pattern via the s-video. I tried the composite mod, but no video. Any ideas? If I can get a hold of a digital camera, I'll take some pictures.

Btw the unibios is version 1.3, so I think a lot of the issues may be due to the early aes support added in that revision. Any one know for sure?

You should update your Unibios to the most recent or at least 2.2 as it had some big changes according to Raz.

Older versions of the unibios never caused such issues. It's more probable that something went wrong with the bios socketing (damaged traces, blobs of solder ending across some chip legs, etc.).

Is your bios socketed? If it is try reseating it in the socket, when mine was giving glitches in my AES I pulled the bios out and lightly sanded each leg that looked dirty and then it cleared up the graphic problem.

But also like MKL said it could be broken traces or even solder globs bridging things that arent supposed to be joined.

I also noticed that sometimes when people try to do a piggy back they use a knife to snip leg #2 and end up scratching the 3 traces that run right by it.

Xian Xi said:

Is your bios socketed? If it is try reseating it in the socket, when mine was giving glitches in my AES I pulled the bios out and lightly sanded each leg that looked dirty and then it cleared up the graphic problem.

But also like MKL said it could be broken traces or even solder globs bridging things that arent supposed to be joined.

I also noticed that sometimes when people try to do a piggy back they use a knife to snip leg #2 and end up scratching the 3 traces that run right by it.

Click to expand...

Ahh, you make an excellent point Xian Xi! It is a socketed version, but I think the contacts are pretty dirty on it, if they are that would explain all of the randomness. I didn't even think of that, doh!

Unfortunately the unibios was a loaner, so until I get my hands on a 27c1024 or 27c210 to burn one myself I won't know.

Also what is the best way to clean the socket? I figure I will use a soft toothbrush dipped in rubbing alcohol and gently brush the contacts and then let them dry. Suggestions?

Thanks for all of the help everyone, I really appreciate it! I can't wait to have a fully working AES!

Okay so here's an update. I have got a new unibios put in the socket, and that solved all of the problems with the random crashes and errors. However, the video problem still remains, and I can't figure it out for the life of me. The best way I can describe it is if all of the graphics except for the text have a uniform grid of small black squares over them. It's strange that the text is fine. I know it is not dirty contacts as I have poured rubbing alcohol in them and scrubbed them at least 10 times and let it dry completely. Not only that, but when I turn the system on without a cartridge in it, it shows a blue screen with the same black squares!?!? I know that a blue screen means all is well, except maybe the z80 which isn't tested so what the heck?

Also when I first turn it on without a game in, before the screen fills with the black squares completely it is about 2/3rds solid blue then slowly does a weird the matrix like effect with vertical lines revealing more of the black squares before the image stabilizes into the uniform black squares over the blue. Also, the unibios menus are all unaffected by the squares with the exception of the Neo Geo logo at startup. I figure it is a bad ic or maybe a transistor, diode, resistor or other part that went bad or is maybe missing. Also what are the two pots with orange insulation around them used for? I'm so close! Thanks again for everyone's help!

I'm not an expert, but similar effects can happen when a cartridge isn't inserted properly, or has dirty contacts. I've seen it happen where the tile layer with the text is fine but graphics are garbled. The unibios uses this tile layer to draw what it needs on the screen.


So you're probably on the right track that some small component specific to the sprite and background layers is faulty.


edit: oh LMAO Lios this is your thread! Well good luck man.