AES not booting up fix

Joined
Aug 30, 2001
Posts
349
I offered to take a look at a friend's AES that could not boot up.

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This was a very first revision board that did not have any daughterboards at all! Completely untouched save for the Unibios installation near the top, and which looked to be somewhat botched.

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I got to removing the socket and starting replacing individual socket pins for each. The rationale was that the board has traces above and below and using such pins allows for clearer tracing and repair.

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This image is post cleaning, it had looked like Vcc from pin 40 was going into the trace.

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The individual sockets were snipped out of these guys.

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All socketed, pre-trace check.

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Trace-checked and re-wired.

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A piece of thick cardboard to cushion the pcb traces from a flathead screwdriver, for future EPROM updates.

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On testing, the AES kept randomly rebooting.


I recalled that a 10V power source was used on this 5V AES and I speculated that some power circuitry might be screwy. Poked around but nothing seemed amiss.

Prior to opening the AES, I had ordered a 5V, 2A PSU with the din plug's center polarity being +ve.

ac-to-dc-55mm21mm-55mm25mm-5v-2a-switching-power-supplyadapter.jpg

The polarity needed to be switched to center -ve and with no screws to the case, I did not want to crack open the adaptor to swap it there. So I got this in-line power switch a week later, and I swapped it within the switch case.

in-line-power-switch-onoff-21mm55mm-cable-jack-arduino-plug-12vcctv-camera.jpg

I did notice that the wire gauge(thickness) used by the in-line power switch was absolutely tiny.
I then thought to just re-wire the adaptor, which had a thicker gauge all through.

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Lo and behold, it lives!


Take home:
1. Bios pin 31 was disconnected to the Sony CXK58256M-12L S-RAM. This appears to be the one causing the strange boot screen.
2. Severe flickering likely due to Vcc bleeding into a trace.
3. Insufficient gauge wire can cause resets!
4. Use a proper desoldering station. Or do the piggyback mount method, leaving the pcb well alone.

Putting it out there for future reference.
 
Last edited:

joala

A Joala is for Life., Not Just Christmas.,
Joined
Oct 7, 2017
Posts
644
Thats awesome - thanks for posting

I'm seriously jealous of these guys that can troubleshoot this kind of shit. Looks like pure wizardry to me...
 

Razoola

Divine Hand of the UniBIOS,
Staff member
20 Year Member
Joined
Nov 12, 2002
Posts
4,662
Maybe this guy would have had a little more luck if he was using an official unibios and not a rip off.
 

GadgetUK

Ace Ghost Pilot
Joined
Sep 27, 2013
Posts
1,323
Maybe this guy would have had a little more luck if he was using an official unibios and not a rip off.
Hehe, good point! If you don't get an official bios - karma catches up with you ;)

Good repair Clear Paper! One thing to note - whilst you did a great job using single socket pins there (not sure I could have got them all so straight!!!), you get additional strength and support using strips of turn pin socket rather than single socket pins. It won't cause any problems though, I am sure it will be fine as is. Well done =D
 

evil wasabi

The Jongmaster
20 Year Member
Joined
Aug 20, 2000
Posts
60,434
Very nice laying out of the thought process in problem solving.
 
Joined
Aug 30, 2001
Posts
349
Maybe this guy would have had a little more luck if he was using an official unibios and not a rip off.

I have to admit that I've a copy of this unibios now. Where do I send the cheque? Seriously. (donation@universebios.com?)

And great work on Crossed Swords 2! I'm slowly catching up on 9 years worth of Neo Geo news and it's mind-numbing.
 
Joined
Aug 30, 2001
Posts
349
Hehe, good point! If you don't get an official bios - karma catches up with you ;)

Good repair Clear Paper! One thing to note - whilst you did a great job using single socket pins there (not sure I could have got them all so straight!!!), you get additional strength and support using strips of turn pin socket rather than single socket pins. It won't cause any problems though, I am sure it will be fine as is. Well done =D

Thanks! These pins are much more solid than the other socket's pins shown in the picture. I didn't favour them in the past but looks like they've come in use! These pins were actually bought more than a decade ago. Lol... :lolz:

Edit: And I love your videos, very well worked through and a great resource!
 
Last edited:

Razoola

Divine Hand of the UniBIOS,
Staff member
20 Year Member
Joined
Nov 12, 2002
Posts
4,662
I have to admit that I've a copy of this unibios now. Where do I send the cheque? Seriously. (donation@universebios.com?)

And great work on Crossed Swords 2! I'm slowly catching up on 9 years worth of Neo Geo news and it's mind-numbing.

:) yup, thats the email, donations are always welcome.
 
Joined
Aug 30, 2001
Posts
349
Thank you! I'm playing through each of my carts slowly and the Unibios cheats makes it a blast in re-discovering things, especially with the shooters.
 
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