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Trenton_net · Joined: 29 Jun 2006 Posts: 233

Which copiers for the SNES use battery backup for SRAM and which use internal AC power? I assume GD7's uses AC, while others like UFO's, Supercom Partner's, Pro-Fig, etc use batteries? A short list would be handy.

Leading into another question... For copiers that have batteries, but won't be in use for extended periods of time (Storage), should you open them and clip the battery out before it leaks, or does leaking usually happen in only special cases?

EDIT: Also, I assume removing the battery doesn't effect copiers functional wise, unless you forget to save to floppy before you remove AC power? Will self-test for SRAM fail perhaps as the only side effect?

kyuusaku · Joined: 26 Jul 2003 Posts: 941 Location: .ma.us

All Bung use the power supply for power.
All FFE use a cell ("battery") when the console is not powered on.
Early CCL are like FFE.
Later CCL are like Bung (but have a big capacitor to retain memory for a short time after being unplugged)
AFAIK all UFO and Supercom and Sane Ting are like FFE. I'm not sure about all Gamars but I think most Taiwanese just use cells.

I think leaking will happen eventually with all batteries that are allowed to fully discharge. I would desolder the battery and keep it in storage or replace it with a coin cell socket.

Removing the battery does affect many copiers functionally because they don't use the optional power supply at all for power, they draw current either from the battery or console (just like a real cart). The copiers will all pass self tests but if there's no battery and the console is powered off, the RAM contents will go.

Trenton_net · Joined: 29 Jun 2006 Posts: 233

Your last paragraph confused me a bit. As I understand it, copiers ether draw power from the console or an external power supply (AC). The battery just keeps SRAM alive when no power source can be found.

But from reading your last paragraph, it sounds like your saying the batteries play more important roles than what I just mentioned?

kyuusaku · Joined: 26 Jul 2003 Posts: 941 Location: .ma.us

Copiers draw from either console or supply, but the SRAM's power is isolated from the main power circuit since the cell should never power anything but the SRAM. I haven't fully checked the circuits in any copiers but I believe from just looking at them, copiers ripped the circuit straight off game carts which switch between two sources, cell and console. Making the SRAM switch between three sources would be more difficult unless you put the console and power supply in parallel which could be dangerous.

Now that I think about it, I can't think of any optional PSU copiers, most copiers require the PSU at least for the floppy or don't need a PSU at all. If copiers were to switch between the console and power supply for the floppy, you'd need a really big transistor + heatsink which I don't think any copiers have.

SpooNMan · Joined: 31 Oct 2007 Posts: 89

madman · Joined: 07 Jul 2006 Posts: 598

I think Kyuusaku answered the battery question in one of your other SMD threads. I've seen leaky batteries still work fine.

SpooNMan · Joined: 31 Oct 2007 Posts: 89

madman · Joined: 07 Jul 2006 Posts: 598

Pretty much every battery will leak over time. The easiest thing would be to install a socket so future battery swaps are less painful. But it'd probably be 10 more years until you'd need to change it again.

kyuusaku · Joined: 26 Jul 2003 Posts: 941 Location: .ma.us

The battery I linked is definitely good enough if you backup your save after playing, it probably wouldn't be good for prolonged save retention though. If you worry about ever replacing the battery, just solder in a coin cell holder and get some common CR2032; they'll last a long time and can be changed without soldering.

SpooNMan · Joined: 31 Oct 2007 Posts: 89

kyuusaku · Joined: 26 Jul 2003 Posts: 941 Location: .ma.us

Nope, I've never done it before, but they'll work fine.

I can't recommend a particular type of holder, probably any will be fine though. You probably want to measure the width between the holes of the old NiCD and make sure it will fit around the other parts. If you have to, you can always install it on the solder side of the board.

Who knows why FFE decided on NiCD. I've never seen a coin cell leak and we all know that they're able to retain SRAM contents for over 10 years. If they wanted something really cheap they could have glued in a 2xAA pack but those would surely start leaking in a year or two.