Would NVRAM work in a 4 slot Neo Geo

brainmegaphone

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Would it be possible to use NVRAM instead of a battery in a 4 slot neo geo? Anyone ever look into this?
 
I'm curious if anyone got it to work and what chip gets replaced. If anyone has done this and wants to provide information in this thread I'm interested.
 
After looking into this and reading on the Neo-Geo forums I think I'm going to go with a super capacitor. No one has tested NVRAM successfully on these boards but they have had decent luck with a super capacitor. My preference is to remove the battery entirely (even if it eliminates the clock from working properly).

Obviously most people are fine with coin cell batteries but I think we can do better than that!
 
After looking into this and reading on the Neo-Geo forums I think I'm going to go with a super capacitor. No one has tested NVRAM successfully on these boards but they have had decent luck with a super capacitor. My preference is to remove the battery entirely (even if it eliminates the clock from working properly).



Obviously most people are fine with coin cell batteries but I think we can do better than that!



how long would the super capacitor last ? Very interesting.
 
how long would the super capacitor last ? Very interesting.

Based on other posts about 90-120 days without a charge. In other words - you can keep the game powered off for that length of time without losing data. If you use the game in that length of time you are okay as the capicitor should charge.

Since the data is bookkeeping only and a clock I see this as a better "risk" than a battery that can leak. I'm going to probably switch it over during the holiday break.

I converted all my pinball machines to NVRAM where possible. Batteries are stupid expensive and dangerous.
 
I would try the NVram (FRam) option first. I don't have any experience with NeoGeo's. Is the ram already in a socket? I've tried the super capacitors in other games but, didn't have much luck with those. I love the idea but, they just didn't hold the data long enough for my usage. Your experience with NeoGeo may be better. With that said, there are two things you need to consider when using FRAM as a replacement. You'll need the schematics or at least be able to follow the traces on the board.

1) In order for the Fram to operate properly, the /CE pin must be strobed low by the memory controller. It can not be held. The /CE can not be a grounded and permanently selected. If there is a trace connected to ground holding the /CE low, you cannot use FRam (NVram adpater). This goes for any game.

2) I've found that most NVram (FRam) adapters do not include a pullup resistor on the /CE. Per the manufacturer, "It is recommended that Chip Enable is pulled high and allowed to track VDD during powerup and powerdown cycles." I've made my own adapters that include this resistor. If you have an adapter already, you can solder on a 10k ohm resistor from +5v to the /CE pin. This solution has worked very well for MCR boards.

The following pics just happen to be 6116 ram adapters, but the information applies to whatever memory adapter you may have that uses the Ramtron Fram chip.

Manually added resistor:
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Incorporated resistor:
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Cmdr Brain— thank you for that. Exact technical help I was looking for to figure this out. I knew someone on these boards has the knowledge!

I have schematics but their resolution scan is horrible and I think I may just have to follow traces. What you wrote there is a huge help to get started.

If anyone has nice clean schematics of a 4slot board please let me know. The ones off the Neo Geo wiki site are not that high res and are difficult to read.
 
Cmdr Brain— thank you for that. Exact technical help I was looking for to figure this out. I knew someone on these boards has the knowledge!

I have schematics but their resolution scan is horrible and I think I may just have to follow traces. What you wrote there is a huge help to get started.

If anyone has nice clean schematics of a 4slot board please let me know. The ones off the Neo Geo wiki site are not that high res and are difficult to read.


People have the knowledge... you just chose to ignore it and reply to people posting completely irrelevant pictures of MCR boards.

Hint: the battery backed ram is SMD.

Pcb_repair_neogeo_4_slot_2_1.jpg
 
People have the knowledge... you just chose to ignore it and reply to people posting completely irrelevant pictures of MCR boards.

Hint: the battery backed ram is SMD.

Pcb_repair_neogeo_4_slot_2_1.jpg

Forgive me but what knowledge have I ignored?

So you mean the ram is a surface mounted device and therefore simply swapping out a chip isn't the solution - which is unfortunate but not surprising otherwise everyone would have done this already.

Can I assume you are trying to tell me this may be more work and effort than it is worth since it isn't a simple chip swap out?
 
Forgive me but what knowledge have I ignored?

So you mean the ram is a surface mounted device and therefore simply swapping out a chip isn't the solution - which is unfortunate but not surprising otherwise everyone would have done this already.

Can I assume you are trying to tell me this may be more work and effort than it is worth since it isn't a simple chip swap out?

Like I said originally, I've been doing this for >10 years...

It's just a simple chip swap, as long as you can desolder and replace SMD chips -- but most people can't..
 
Like I said originally, I've been doing this for >10 years...

It's just a simple chip swap, as long as you can desolder and replace SMD chips -- but most people can't..

Excellent. This is very helpful. Thank you. When I pull my board next week I'll follow the traces and I should be able to see what chip needs swapping. (I'm too blind to see in the photo!)

I'm not a huge fan of non socketed chip work but I have socketed a few things on dead MPUs for pinball boards and watched them come back to life. This shouldn't be too different.
 
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