NES Zelda cart save issue

[Hobie-wan]

So Sevin got this Zelda cart and it wasn't saving for him. The reasonable assumption was made that the battery was probably dead. The first thing I did when it got here was open it up and check the battery. 3.2 volts still. I checked that the spot welds on the tabs were good since Sevin also sent me a Super Metroid cart for battery surgery which turned out it's welds were popped so the battery would lose connection when the cart was shaken.

I popped in the Zelda cart and there was already a virgin 'Link' on there with no equipment or deaths. I ran around, collected a little money, then let myself die and saved. I shut down and unplugged the cart for an hour. Came back, file was still there ok.

I created a second save file. Played and beat the first dungeon and saved it with no deaths. Unplugged and checked after a while, everything was still there.

Created a 3rd save file and beat the first dungeon with no sword since I'd never done that before. Unplugged, checked later, everything still there.

Previous tests were yesterday. Went to check it again now and the first save is just gone. Second and third slot are fine and load up without problems. Maybe the first save slot is damaged on the chip? Anyone have any ideas?

[sevin0seven]

...please

[Ziggy]

I've had weird problems like that with my Final Fantasy 3 (Famicom in Gyromite converter) cart. Some times just one save slot would erase, some times all. The battery was good, I put a new one in any way but that didn't fix anything.


Could it be possible that the SRAM chip is bad?


And I'm not entirely convinced that the NES itself isn't responsible to erasing saves. I've read that when you power the NES off, it puts the CPU into a weird state that can write to the SRAM, and that's why it says to hold reset when you power off the NES on the back of carts with SRAM. Though, for years I NEVER held reset when powering off and I never lost any saves on NES carts.

When I lent my FF3 cart to my friend I told him to hold reset, but he still lost saves a couple of times. I made him replace his pin connector, and he hasn't lost a save since then. I don't know if the two are related or not.

[Hobie-wan]

I was testing in my Gen Nex as opposed to a NES just to try and eliminate any contributions from blinkies even though my NES has a fairly new slot in it. Hmm. I guess we'll see if anyone else has any suggestions and I'll continue testing. Thanks for your input though.

[Mod_Man_Extreme]

It's the battery.

Basically playing the cart in the NES means the battery isn't being used, after it's turned off it only takes a short while for the data to disappear because the battery itself is bearing the full load again.

The easiest analogy is like when you were a kid and tried to use a GameBoy as the batteries were dying. Once it dies on you once you put it down and come back in 30 minutes or so to scrape another 5 out of them.

[Ziggy]

Yeah, but Hobie said he tested it WITH the full load and it was 3.02V, which is perfectly fine from my experience.

edit: I have noticed the batteries read a different voltage though when they're on or out of the cart. For example, I tested a "new" battery and it was 3.02v. I put it in a cart and then it read below 3v. So that's definitely something to look out for. But if it reads over 3v while it IS on the cart, then it should be good to go.

And while I'm on the subject, I've tested "new" batteries (as in, I took it out of the factory sealed package) and found them to be below 3v.

[jeffro11]

When the NES and ANY clone turns off the CPU does into a state that CAN erase the SRAM. You MUST, I repeat MUST hold the reset button to prevent data loss.

The reset button puts the NES into a safe state (no cpu activity at all). Therefore it couldnt possibly write to the SRAM. There is nothing guaranteeing a clone will act the same. They are designed totally different and always on since its basically a glorified emulator.

Try it on your real NES and please use the reset button and report back.

However like Ziggy stated... The SRAM chip could be the culprit as well.

[Ziggy]

Hobie, you should take an SRAM chip from another NES cart and put it on the Zelda cart that's having the problem. Just be sure the SRAM chip you're gonna use is from a cart that's known to be working fine.

If the the Zelda cart saves find after the SRAM swap, then you know that's the problem. You can get a new SRAM to replace the bad one for dirt cheap.

[Hobie-wan]

Hobie, you should take an SRAM chip from another NES cart and put it on the Zelda cart that's having the problem. Just be sure the SRAM chip you're gonna use is from a cart that's known to be working fine.

The problem is not having a cart I want to lose my own saves on.

I did manage to make it lose the first two saves by going apeshit on the power button. The third still held though. I wasn't holding reset when I lost the first save before. Sevin thinks he was holding reset, but isn't 100%. So maybe this is just all reset button related.

Granted I think I only had Zelda and Crystalis as battery backed NES carts that I played a lot back in the day, but I never held reset back then. The only time I remember losing saves was when my NES had the blinkies really really bad. I'm gonna leave it as is for the rest of the week and if I don't lose another save and keep using the reset when powering off I'm just going to chalk it up to that.

I appreciate everyone's input though.

[Hobie-wan]

So after a week of testing and always using the reset button, it didn't lose the saves anymore. So I'm just chalking it up to that even though I never used reset back in the day with Zelda or Crystalis.