N64 save-files gone awry - is the internal battery dying?

[NJC]

Hello, this is my first time posting here - long-time lurker, first-time poster, I suppose. I'm a casual collector/enthusiast of N64 and SNES games (perhaps more systems later), and was recently happy to purchase a Legend of Zelda: Ocarina of Time cartridge in excellent physical condition, as I had never had the privilege to play it until now. (Long story short - read the underlined text below)

After four attempts to play this game, there is definitely something wrong with this cart's ability to save my progress. The last time I saved, I had visited Zelda, received her letter and learned the first song. Today, I tried to re-load the game and Navi is telling me to talk to the Deku Tree, which I had to defeat in order to leave the forest and visit Zelda in the first place. Moreover, another character blames me for the death of the Tree, which could only happen AFTER I had visited it and completed its contained dungeon. If I visit the tree, it is still alive and asks me to complete the first dungeon. I still have Zelda's letter, the slingshot (obtained inside the tree in the first dungeon), the ocarina (obtained on the bridge outside Link's village... and if I leave the village, I watch a cutscene of Link receiving the ocarina AGAIN). The game wants me to replay large portions to collect items I already have collected. It's obviously screwed up.

My thought is that the battery is dying and is unable to make proper saves. If that is the case, I will dig up a guide on replacing the battery... but I just want to (hopefully) confirm that this is indeed the problem before I go through the hassle. Are there even other possibilities?

Thanks in advance! Hope this was the right place to post.. The Nintendo forum did not seem to have technical posts.

[Hobie-wan]

It definitely could be the cause. Some N64 carts had batteries and some had eeproms. Not sure offhand if Ocarina was a battery cart. I can check later.

[Ziggy]

I think some might have had both. I forget if it was Mario 64 or OoT, but I read that the game had an EEPROM inside. For one reason or another I opened that cart up and found that it had a battery. I don't know if I read misinformation, or if some games had batteries OR EEPROMs depending on the version. I know OoT has at least 2 different cart versions.

NJC, that sounds less like a battery problem and more like corrupt saves. As far as I know, the battery will either hold that data or it wont - the save will either be there or it wont. If the battery loses voltage to a certain point the save file(s) might drop out sporadically, but I don't see them becoming corrupt.

If the cart contains a battery backup, I would think it's more likely that the SRAM is going bad. Likewise, if it contains an EEPROM, I would thing it's more likely that the EEPROM is going bad. From my experience, it's a rare occurrence, but RAM does in fact go bad. And on that note, EEPROMs can definitely go bad.

If it were me, what I would do is open the cart. It's pretty easy to identify if it has a battery or EEPROM (if there's a battery there or not). If the battery IS there, test it with a voltage meter to make sure it's still good. If the battery IS still good, I would go ahead and swap out the SRAM chip. If the cart contains an EEPROM, I would swap that out. These parts are cheap.

Of course, you need a security bit to open the cart. And replacing the battery, SRAM, or EEPROM requires soldering.

[NJC]

Thanks very much! I didn't realize that the RAM itself could go bad. Kind of discouraging, actually...

Doing some research (yay Google) strongly suggests that OoT cartridges are all SRAM, meaning they are battery powered. I have a gamebit but do not yet have the time to open the cartridge and confirm its RAM type.. Once I can do this and test with a volt meter, I may need to ask for more guidance on replacing the SRAM if the battery is A-OK. I am a novice when it comes to soldering and that sounds like a tricky operation.

Maybe I'll pick up some cheap sports games at the local goodwill to practice on.

[Ziggy]

Does the weird save issue happen ALL the time, or just some times? Because if it just sometimes, then everything on the cart might be fine. It could be that the cart pins and/or system cart slot are dirty and the saving process got screwy. This is more likely, now that I think about it. But it depends, you didn't say if this problem happens EVERY time you save, or just sometimes. The SRAM going bad is a rare thing to happen.

I popped open my two OoT carts (one gold, one grey) and they both have batteries.

[Hobie-wan]

NJC, that sounds less like a battery problem and more like corrupt saves. As far as I know, the battery will either hold that data or it wont - the save will either be there or it wont. If the battery loses voltage to a certain point the save file(s) might drop out sporadically, but I don't see them becoming corrupt.

Just remember that Saturn onboard saves can get screwey when the battery is dying.

But anyway, yeah, what Zig said. Check the battery and go from there.

[Ziggy]

Definitely clean the system and the cart, make sure they are completely clean!

[NJC]

Thanks everyone for your help!

Following Ziggy578's suggestion I decided to clean the cart first, before opening the cart (my system was cleaned not long ago) and tried again. And lo and behold...

The cart can't even remember I ever played the game. My file is completely gone! Not only that, but a save file from the previous owner is now corrupt and can't be played.

I believe this indicates a failing battery (because of the progression... so rapid though!), not a(n) SRAM failure or a dirt problem. Next step is to follow a guide for replacing the battery, which I've read is the same procedure as replacing a SNES battery and shouldn't be too difficult.

[Ziggy]

I believe this indicates a failing battery

Yes, that sounds most likely now. Just for good practice though, when you open the cart, if you have a volt meter handy, test the voltage of the battery anyway. And make sure you test the battery before you remove it (it will have different readings on and off the cart). I've seen these same symptoms plenty of times when the battery was perfectly fine.

As far as replacing the battery goes... the most common method you'll find on the interweb is to remove the solder tabs from the old battery and tape them around the new battery. I'm not a big fan of this method, but a lot of times it's the best you can do.

You can actually buy CR2032 batteries with the solder tabs already spot welded on, but they're a little more money. I think it's more than worth it, but for some reason they're not too easy to find with the tabs. Only ones I could find on eBay right now...

http://cgi.ebay.com/20-CR2032-Coin-Cell ... 5632f8c97c

Though my search criteria might be bad. Still, $2.40 each for batteries WITH the tabs isn't a bad price (I might get that myself) but I doubt you'll wanna buy 20 batteries. You can find them on various online stores. I know Digi Key has them on their site, but the stock says 0. It's a lot easier, and better, than the "tape" method.

/rant

[Hobie-wan]

http://cgi.ebay.com/20-CR2032-Coin-Cell ... 5632f8c97c

Nice find, I hadn't come across any tabbed 2032s on ebay before and on other sites they were a lot more. The corded laptop batteries I got were a little cheaper though and I didn't have to buy 20 of them. Just as good with being able to solder the contacts, then just a little electrical tape to make them stay still.

FWIW I bought some tabbed NiCd batteries to fix my beard trimmer from that seller and it was a quick and painless transaction.