Neo Geo Battery Replacement with Lithium - How

Teknotoyz

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I've been FUBAR'ed the last 2 days with machine issues. :(
Along with rebellion from the Wizard of Wor, my MV-1F Neo-Geo motherboard has just begun reseting somewhat continuously.
The "somewhat" part leaves me a little hope it's not too far gone.

I've been reading through Channelmaniac's repair logs, I feel a little bit more confident, but lacking the logic tools (it's very cool he has done this!!).
http://newlifegames.net/nlg/index.php?topic=152.50

So... I pulled the cart slot off, and behold the battery is lightly corroded, not bad, but likely the problem (a problem at least).
After seeing this and reading the logs, I took a look at my 2 other Neo Geo's... dang, their batteries are also corroded.

I'm gonna look for basic stuff that corrosion could have caused, but beyond that I will need need to hire help on the repair.

===========

One thing I can do for all three PCB's is to install lithium battery holders in place of the old NiCd, but I need some help.
The holder is pretty straightforward, but where is the best place to put the diode to stop the charging circuit?
Also is it a CR2032 lithium battery OK to use? (3v vs 3.6v)

PCB's I have:
- MV-1F
- MV-2F
- MVH Slot4
not sure of the 4 slot version, has two boards.

Side question:
How to remove the black foam on the underside of the PCB?
What purpose does this stuff serve anyway?
 
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I'd put the diode on top of the battery. Make sure you use a schottky, they have a voltage drop of about 0.3-0.4v compared to the 0.6-0.7v of a standard silicon diode.

It is worth mentioning that you can get rechargable lithium batteries. They are not common but they do exist.
 
There's no need to use a diode when putting a coin cell lithium battery on a Neo Geo board in place of the NiCd battery. You simply pull the 470 ohm resistor off the board as that is what charges the battery.

This does not work for the boards that come from SNK using the small lithium rechargeable coin cells. I haven't looked at those to see what it would take to convert them.

RJ
 
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