Nintendo 64 (N64) Memory Pack Repair & Warning 

FRAM would be a much better solution to this problem than replacing with another battery powered SRAM. Drop an FRAM in and forget about it for the rest of it's existence xD

this sounds very similar to Doctor V64 (device that Nintendo hated so much because it was used for copying N64 games)

I did use the Southpark file manager too! I tried a bunch, and also tried the Everdrive (format game pak option) and that wouldnt work either. Was definitely the SRAM!

That's interesting; I've noticed some games definitely have a "better" interface for the manager than others. I assumed that every game that utilizes the memory card had a manager built in but that isn't true (Off Road Challenge comes immediately to mind). Then there are some games that have the manager even though they don't use a memory card.

Isnt it volatile? No power=immediate erase of all data?

I just dropped fram into my official N64 pack and it won't format using Perfect Dark, I'll have to give this a go. All solder joints are good so I'm stumped. We shall see!

When I get more time I will install an FRAM into one of these! =D

Would there ever be a chance of a N64 booster pack mod. reason I ask would be there any reason not to try doubling the amount of ram if the system could handle it. not that any game would need it just would be great for home brew having more N64 ram to run emulation off an ever drive.

Yes, the PCB in this video seems to support larger chips. In theory it could be possible to piggyback a 2nd 62256 chip on there and with some added logic to switch between the chips on the upper address bit it could be made to work I think.

​@@GadgetUK164 Thank you sir!

Thankfully the VMU on the Sega Dreamcast doesn't have this issue with sram. Those really eat batteries so does the wii remotes.

Thanks, the repair option wouldn't have worked here as the SRAM had died =/

Thanks for the info there =D Very useful =D

Yes, depending on how they are wired. If the SRAM gets powered by the N64 via the cart edge, then it would likely be OK. But if the SRAM is solely powered by the battery, and the battery is flat or missing, then latch-up is entirely possible. I haven't got an original pack to see how they are wired, but on these the battery seems to provide the sole power to them.

so going by what you're saying, you will basically kill the SRAM simply by removing the battery, weather the battery is still good or not? What's the point in the pak giving you the ability to remove the battery then?

No, you can kill the SRAM by powering the unit without a battery - or a bad battery. The big problem with mine is the battery bay shorts out the contacts, so if you powered it with no battery, that would kill the SRAM. And the contacts are really bad, so when you do swap out the battery you need to make sure it is connecting before powering up.

AndehX Like a game cartridge with a removable battery, it’s internal and isn’t intended for end-user replacement. It’s intended to last a decade or two before running flat and losing your data. Still should’ve been engineered in a way so that the SRAM wouldn’t get fried when the battery dies. I’m surprised these 3rd party controller paks didn’t use soldered-in tabbed batteries like most SRAM game paks but that’s probably just parts bin engineering for you.

AndehX ...oh yeah: it also appears safe to preemptively remove/change the battery (Edit: With the checks/precautions Gadget just suggested ;)). It only kills it if you attempt to use the controller pak while the battery is dead or removed. Because most people wouldn’t consider changing the battery until after finding their saves gone, most people will have already fried it. Sucks!

No, it was a faulty SRAM! Formatting it using various methods there (including the format build into the Everdrive) always resulted in it no being usable. The battery not being connected properly caused a latch-up, killing the SRAM.

That wasn't the case with this - the SRAM had died.

What has happened is the battery wasn't connected properly whilst it was powered, causing a latch-up fault. That does look to have been the cause. Before the battery was 1st removed to measure it, it was working perfectly. When the battery was re-installed, one of the connections made a really bad join to the point it wasn't powering the chip.

Yes, it's an interesting point, and there might be other factors to consider. In the case of the Neo Geo, when there's no battery at all - the system works! I ran mine like that for 3+ years and the SRAM was fine. Where I think the problem can occur in the MVS is when the battery has failed and it perhaps provides some resistance, so the power that normally feeds its VCC rail (via the charge circuit), perhaps pulls the VCC down below the logic level the data and address buses are driven with. At least that's what I think is happening on the MVS. But in this case there is no 'charge circuit' on these cheap mem packs, so I think there's much more chance of latchup even when the battery level drops over a few years. eg. imagine battery drops to 2.0v, and data / address bus logic level is 3.3v...

Sounds like the Joy Tech ones do at least have a capacitor in there to provide some charge whilst you swap out the battery - that assumes the battery hasn't dropped to 0v. I would certainly replace any CR-2032 cells in these every few years at least.

SRAM can have a good bit of data retention without any power on its own - just on the internal capacity of an IC. Not sure if it will hold a minute or so. Bad things happen when you short the power inputs though. Wait, is there possibly a diode to prevent that?

The diode seem to just be in series with the battery supply - presumed to protect against the battery going in the wrong way. that kind of exacerbates the problem since there's also a 0.7v drop from that too.

Mhm that's a 5V SRAM that you installed - recommended supply voltage 4.5V or higher, retention 2.0V. IO voltage needs to not be higher than supply voltage plus 0.5V. That's kind of hard to reach on a 3.3V system while running off a 2-2.5V (considering diode drop) battery supply. Sure the second diode isn't there to actually power the SRAM from the system voltage (with a bit of a drop) when running in console? Then the battery diode protects the battery against potentially explosive charging. Ultimately that's all they care about, as a cheap product it must only last as long as the warranty, which means likely before the first battery replacement is due.

Yes, you probably can! I completely forgot to focus on that aspect. But yes, pretty sure that's what the other 4 pins are for. Assuming you can go to a 1MBit chip from the current 256Kbit I have fitted.

So, topic for next video, right? 😀

Pretty sure I didn't to be honest! The only reason I mentioned it is because that would almost certainly cause the failure. I believe the battery wasn't making a good connection. It's definitely a common problem related to the battery level dropping as I've read a lot about it and how swapping the battery is hit and miss. Changing the battery is often too late after it's dropped too low.

And after the failure, the dump of the CPAK was just blank - no data there at all. So SRAM just wasn't holding anything.

I would expect the SRAM to be empty after the failure addressing it was happening, since the contents were lost by the battery being removed (assuming you didn't power it on with the connectors shorted and fry it). If we had that empty 32k file, and could do a hex compare against the original dump before removing the battery, we could maybe see if the signature or nintendo data was there (alongside whatever saves were there, but I am thinking it might stand out somehow).

Actually, scratch that, if it was all zeroes, then you wouldn't even need to compare -- the original copy would be enough to examine. :^)

It's of course possible to make anything =D But just not worth the effort tbh! It's far easier to just buy a spare one off eBay for £20 or something. They do use a specific type of RAM - RAMBUS I think? But I am sure you could replicate it with some other type of RAM. And yes, you could easily hombrew one of these memory packs for sure! Nice thin small PCB - easy to make your own, and maybe 3D print a shell. Use FRAM instead of SRAM and you don't need a battery =D

For the homebrew, it does seem kind of silly the way the n64 does not have a homebrew 16meg RAM upgrade (so that is basically 12meg + 4meg existing). And also for it to have something like the DD made (but maybe using a SDcard or emulated zipdisk in a 256Meg chunk of RAM pretending to be a HDD or whatever). Surely it will become a thing. I have hope for it.

Thanks! Nor me! I couldn't believe that it had died just from the battery not making a proper connection tbh. I spend a number of days trying to rule everything out - but it 100% certainly had a dead SRAM at the end of the day. Worked fine before I removed the battery to measure it =/

The battery wasn't providing a supply to the chip at one point (just because of how bad the battery connector is in design). That caused the latch-up =/

Oh wow that is horrible.

@@GadgetUK164 Just for clarification, that would mean that the same would happen if the battery died or wa removed, which you stated in the video. Odd to me that losing power at any time would destroy an SRAM.

@@GadgetUK164 Saw further details in your other comments: (Using one with a dead battery could kill the SRAM) depending on how they are wired. If the SRAM gets powered by the N64 via the cart edge, then it would likely be OK. But if the SRAM is solely powered by the battery, and the battery is flat or missing, then latch-up is entirely possible. I haven't got an original pack to see how they are wired, but on these the battery seems to provide the sole power to them. (You) can kill the SRAM by powering the unit without a battery - or a bad battery. The big problem with mine is the battery bay shorts out the contacts, so if you powered it with no battery, that would kill the SRAM. And the contacts are really bad, so when you do swap out the battery you need to make sure it is connecting before powering up.

Yes, someone asked that too =D I think a 1Mbit chip would probably work.

It's a good idea, but there's a problem with the mem packs I have - if you remove the battery, the + and - connectors for the battery SHORT! If the pack was powered by the N64 that would cause the N64 PSU fuse to pop probably. If the battery contacts don't short, and assuming the SRAM is powered by the N64 (not sure it is in mine), then you would be OK. But pretty sure with mine the battery is the only source of power to the SRAM, even when connected to the N64.

Well seems my curiosity is cured with that "what if" :)

tbbw and if it were an original memory card you wouldn't be able to get in there with a soldering iron to replace it while it was plugged in :( unless you too the controller out of its shell too

It was more an idea of how not to loose your saves or damage the sram if it was undervoltage that was the cause. Just random idea that popped into my brain while watching the video that i wrote a comment about :)

You could solder some wires onto the battery connections on the PCB, connect up to another battery in parallel, then remove the onboard battery. Need to be careful whilst soldering though and you could use that technique to swap the chip - only the battery. If you try soldering the chip whilst its powered you would likely lose the data and possible kill the SRAM.

Off the top of my head - not 100% sure! You need to look at the part number of the RAM on the N64 (and its specs / pinout) and compare to the RDRAM on the DIMM / SIMM. It might be bespoke to the N64 - not sure!

LOL! Well done! Nothing beats that "I fixed it fuzzy feeling" =D How is it not performing well - struggling to read?

GadgetUK164 - Retro Gaming Repairs & Mods yeah a few "backup" really struggle and a couple or original wont work unless the disc is perfectly clean. The mega cd 2 read everything fine. Ill clean the laser lens first but i do have a replacement laser. The mega cd 2 was just the fuse. Someone gave it to me so free mega cd for me.

Not easily I think - the N64 cards use special serial PROMs =/

@@GadgetUK164 thank you

I've not heard of that problem =/ You might need to take the controller to pieces in order to work out how to remove it, and inspect closely to work out how to stop it getting stuck in there!

Technically they probably can, but I've never seen one leak. They tend to just go low voltage and just sit there. Occasionally swell a bit.

GadgetUK164 - Retro Gaming Repairs & Mods i opened my Sega Multi Mega and it uses a rechargeable cr2032. Didnt know they existed.

Yeah, the Mega CD v1 has a rechargeable CR2032 I think too!

What's the problem?

@@GadgetUK164 I inserted it the first time, didn't boot. The 2nd time I pressed on it a bit from the top, and it booted but froze during the intro of Pokemon Stadium 4. And now it's just dead. Won't work with any kind of pressure. The cartridge pins do not run all the way down to the lengt of the cart where it meets the slot. Is that normal? I'm thinking of baking it in an over for a bit, or maybe using an eraser on the pins and then a fibreglass pen to rub the connectors with.

Thanks, it was way too loud on my early videos! Music is used much less now and a lot quieter.