Macintosh SE/30 without battery

[mc9625]

As many of you already suggested, I've removed the internal battery from my SE/30, in order to prevent future damages.

What is really annoying now is that every time I power up the Macintosh, I have to re insert a lot of settings, for example mouse speed, sound volumes etc.

Is there any way to store this settings permanently?

 

[tanaquil]

The battery is what stores the settings. If you're OK with moving the motherboard in and out (I know what a pain it is on the SE/30), the best solution is to put a brand new battery in while you're using the machine regularly, and remove it before moving the machine into any long-term storage. A new battery should last for several years, but I went for almost fifteen years between my last classic mac phase and the current one.

I think I have seen some people run a cable to the outside of the machine so they can attach the battery externally, but personally that looks kind of ugly to me.

 

[onlyonemac]

I've often wondered if it would be possible to replace the PRAM with one of those flash-overlaid RAM chips that save their contents to flash on power-down. Unfortunately I think the PRAM chip is a custom part.

 

[bigmessowires]

You could probably replace it with a little module that combines a basic microcontroller with a standard Flash memory chip. The mcu could "speak" the PRAM command protocol and cache the contents in its local RAM. That would be kind of neat.

 

[olePigeon]

That would be awesome.  I bet they'd sell in droves to collectors.  Buy one for each Mac.

 

[bigmessowires]

How big is the PRAM? Not very big as I recall, like 256 bytes? In that case, you could store the PRAM data directly in the microcontroller's internal Flash or EEPROM memory, so no external Flash chip would be needed.

I can't remember what the PRAM chip looks like, but it's probably not socketed, so it would be a pain to replace.

But now that I think of it, the original idea has a flaw - you need a battery to keep the real-time clock going while the computer is off. An mcu with flash could store the other settings, but wouldn't help with the clock.

 

[olePigeon]

What about a windup analogue system like an old watch?  Especially if it has one of those self-wind kinetic gizmos.  Just make sure to give your Mac a good smack every now and then so it stays wound up.

Or maybe a big counterweight system.  Then you can have a large brass key sticking out the side.  Crank it up once a week. )

 

[rsolberg]

I like making the batteries external. For some of my machines using cylindrical PRAM batteries, I've cut a piece of dowel to match the dimensions of the battery, attached terminals to the ends with brads to create a dummy battery. I've run the wires to a battery box outside the computer with 2 AA or AAA cells. With a couple machines, I've put a connector outside the case so I can easily disconnect the battery holder for portability, or connect multiple systems to one holder. I've found the systems that came with a 4.5v Rayovac cube seem to tolerate the 3v from two alkaline cells just fine too, but I usually supply them from 3 AA or AAA cells.

 

[Dwest]

It was nicely done on the original Mac through the Plus. Had a nice outside door above the AC plug for the battery...

 

[olePigeon]

That's a great idea, actually.  Dummy battery with leads to a wire with an AC plug that snakes out the Lock slot (doubt anyone uses that now anyway).  Just plug in a 3.6v AC adapter and you're all set.  Never have to worry about batteries exploding in your vintage Macs.

Hmm.  I think I might try and throw something together this weekend and give it a whirl.  Could make it look professional if I can print out a face plate that slips into the Lock slot and holds the AC jack.

 

[techknight]

Wasnt there an extension that saves PRAM info to disk on shutdown/reboot? 

 

[olePigeon]

Worried about the clock, though.

 

[bigmessowires]

I don't think saving PRAM to disk would be useful, since some of the PRAM settings like the selected boot disk and 24/32 bit addressing would need to be known before you even load anything from a disk. Or even if there is no disk.

 

[CC_333]

Well, how about tapping off the internal power? You can take olePigeon's idea, but instead of a clunky wall wart outside, just wire a small 3.6 VDC power supply to the mains on the analog board. That way it's energized whenever the machine's plugged in. No muss, no fuss.

The only issue here is that it would not keep time if it were unplugged. Maybe to fix that, a small circuit with a sufficiently large capacitor (something of several tens of thousands of microfarads, maybe?) could be added that would supply power to the PRAM and RTC for a few minutes or hours while disconnected from AC so the machine can be moved and stuff?

c

 

[olePigeon]

Of course, for $10 you could just get a lithium battery and not worry about it leaking.

 

[CC_333]

Yeah, but it's a sort of a "because it's fun" sort of thing.

c

 

[bigmessowires]

Of course, for $10 you could just get a lithium battery and not worry about it leaking.

The voice of wisdom is so rarely heard here...

 

[mc9625]

Could someone suggest where to find a replacement lithium battery for PRAM?

 

[olePigeon]

http://www.ebay.com/itm/1-2AA-Size-ER14250-3-6V-1200-mAh-Lithium-Battery-/170827783822

$4 with free shipping.