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Warning! Exploding Maxell PRAM Batteries


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I've got 3 IIgs's and the Limited Edition one has the battery on pigtails under the PSU, the other two have em in a different location in a plastic holder. And of the SE's, my old dual-drive SE and my current SE Superdrive had the soldered-on pigtail batteries too, but dad's SE FDHD had a removable Tadiran battery dated 88.

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and the II series had to have good batteries to turn the PS on? if i remember correctly...

 

Yep. The II, IIx, and IIfx use two batteries, one for the softpower circuit, and one for the PRAM.

 

I've got 3 IIgs's and the Limited Edition one has the battery on pigtails under the PSU, the other two have em in a different location in a plastic holder. And of the SE's, my old dual-drive SE and my current SE Superdrive had the soldered-on pigtail batteries too, but dad's SE FDHD had a removable Tadiran battery dated 88.

 

Sounds like the two with the plastic holders might be ROM 3 machines, or late ROM 01 machines. My old IIgs upgrade kit machine (ROM 01 version - board installed in June/July 1989) had the soldered Tadiran. Wonder if your SE Superdrive machine has an earlier board with the updated ROM chips. Both my original SE (a dual FDHD machine) and my current SE Superdrive had/have the removable batteries.

 

-J

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  • 2 weeks later...

My turn ...

 

mini_982114IMG2434.jpg

 

Scared by this thread, I decided to remove dead batteries from the most easily accessible in from my collection.

I removed 12, only 1 leaked, guess what brand it was...

It was in my PM 8100/80. Even the optical drive has signs of corrosion :O

 

Funny, the exploded/leaked Maxell battery was the newest of the 3. It had an expiration date reading 1993, while the two other had 1989 and 1990.

 

Those Sonnenschein Lithium batteries (the blue ones) seem to be reliable anyway.

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Found one of these things in my Yikes G3…

 

Compared to the other brands, the Maxell one has a longer + Contact, and less battery… Could that somehow be the cause of these exploding batteries?

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I don't think storage conditions have much to do with it, though heat does speed up chemical reactions, so warmer conditions may speed it up a bit. Honestly I'm surprised so many of these cells *don't* leak after so many years. It's remarkable that one could go 20+ years without leaking the caustic stuff inside. Personally I would not leave a battery more than 5-6 years old in a system. 10 years is pushing your luck, longer than that is just tempting fate. If the machine will be stored for a long period, just be safe and pull the battery. It's not like there are a ton of settings that need to be restored.

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  • 2 weeks later...

The replacement board arrived today, but it was so poorly packaged that it was damaged during transport: ><img src='https://68kmla.org/forums/uploads/emoticons/sad.gif.fd4612761a7f036f230186185c887adf.gif' alt=':('><

 

A chip and a cap were floating around in the box :

520801IMG2464.jpg735238IMG2465.jpg 317762IMG2468.jpg

 

They come from the areas in the yellow and red circles.

974470IMG2466.jpg

 

Great. Now I'm stuck with two damaged boards. Repairing is not an option since my soldering skill is... Zero.

 

Sorry for being off topic, but I wanted to share this "experience". :disapprove:

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Those caps are shot anyway, you can see the leaked electrolyte, the corrosion is why those parts fell off in the first place, look at how black that solder looks. Even if it was well packed, it would still need to be repaired.

 

Any board you find will need to be re-capped, so if you can't solder yourself, you'll have to have someone else re-cap the board for you. Those old SMT electrolytics just don't last very well, the old ones have all dried out or started leaking. This particular board looks like an easy fix, just clean it up, re-cap and solder that oscillator back on.

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