1ST gen AES - dead 68K ?

[Atro]

Sorry for the shaky video.
I was on my knees and trying to hold the probe ( missing the pins I wanted ).

I checked all connections between the Bios to the CPU, Ram and CO / BO chips. They all cleared the continuity tests.

Dead 68000 ?

 

[Razoola]

Its not the 68k, it looks like a workRAM error to me.

https://wiki.neogeodev.org/index.php?title=System_self-test

 

[Atro]

Bumping this!

I've spent some time on this AES again today and I got different results.

The two upper SMD rams were successfuly swapped from an MVS donnor board.
The BIOS is now socketed - the original BIOS fried along with the rams.

So I popped a Unibios and with some games, I get to get at least some error screens from the unibios.
Finally I'm getting something else other than that click of death.

Raz ( or someone else! ) do you know what is not communicating with the BIOS from these errors?

Thanks in advance.

 

[Razoola]

The unibios is showing as bad for one so you need a good unibios first.

 

[Atro]

The unibios is showing as bad for one so you need a good unibios first.

It's weird because it works on a MVS board!
PM on your way.

 

[mikejmoffitt]

Are all address lines pulsing as they should on the BIOS?

 

[Atro]

Are all address lines pulsing as they should on the BIOS?

I don't know what pulses should show on the probe yet, but I might check that this week.

 

[Atro]

It almost liiiiives!

Now I'm pretty positive that it can only BIOS issues or Work Ram.



It crashes just after the tutorial demo.
I will need a spare BIOS to rule this out. If not, I'll swap rams again.

 

[HeavyMachineGoob]

Do yourself a favor and buy fresh (or nearly fresh) SRAM. Don't recycle 20 year old RAMs off an MVS board.

http://www.buyicnow.com/it.php?i=350

 

[Razoola]

Is it an original unibios or one you have programmed yourself. If its one you have made yourself please let us know the EPROM type and speed.

Raz

 

[Atro]

Is it an original unibios or one you have programmed yourself. If its one you have made yourself please let us know the EPROM type and speed.

Raz

It was given to me. I never used Unibioses on my systems before as I always had MV1B's and my AES.

I assume it's a free version one.

 

[RetroTechRewind]

It was given to me. I never used Unibioses on my systems before as I always had MV1B's and my AES.

I assume it's a free version one.

If you want a regular 'ol AES bios, I can pull and burn a copy onto an EPROM for you.

 

[HeavyMachineGoob]

I have an extra original JPN AES BIOS if you'd prefer that.

 

[Atro]

I thank your generosity, both of you!

A JPN BIOS would come handy, since it'd match the system as it's also Japanese!

 

[Atro]

It LIIIIIIIIIIIIIIIIIIIIVES!

Razoola was right.

It happened to be a work RAM problem.
I'm at work so, I cannot get into my pictures folder. I'll post 'em later.

I desoldered 2 SMD ram chips from an MVS donnor board and swapped them with the AES ones.

However, two of the SMD solder pads went off.
One of them was easy to patch as it was easy to follow. The other one was almost invisible and after a lot of continuity tests, I couldn't find where it goes. I just then scrapped a little bit of the trace and patched it directly there.
Of course I don't want it to be a definitive solution. I believe it's the 27th pin on the upper located Wram on model one. Anyone knows where it connects?

 

[bustedstr8]

https://wiki.neogeodev.org/index.php?title=Schematics

 

[Atro]

Thanks Busted.

Totally forgot about that site!
Will take car of it tonight.

 

[Atro]

OK, so I took those rams from here :



And replaced here:



Running on the original Japanese BIOS.
Thanks to Heavy Machine Gun.

 

[HeavyMachineGoob]

Congrats on the repair, always great to see another AES back in action.