Macintosh II batteries

[amedeo_68k]

Hi, I would like to remove the battery from my Macintosh II, however I see that that it have two batteries, and that thay are soldered, see pic.
While is not a problem to phisically remove them, I wonder why there are two, may be they are in parallel as backup and the machine gets bricked if both are removed. Does anyone knows ?
Thank you
Amedeo

 

[davidg5678]

The startup circuit in this computer needs a higher voltage than just one battery provides, so there are two.

It's okay to just snip the battery legs, and pull them out of the computer that way. They can be replaced with either CR2032 batteries or 1/2 AA batteries. A battery holder can be soldered to the existing terminals.

The computer won't be bricked when you pull these batteries out. In fact, it wouldn't surprise me if they both lost all their charge many years ago.

 

[joshc]

In addition to clipping those batteries off, you also need to recap your Macintosh II. The original electrolytic capacitors are leaking on the logic board.



The electrolytic fluid damages traces and IC legs, you can see crud build up on UC7 there.

Sorry if I'm pointing out the obvious, but hopefully that's useful information.

An explanation of the Mac II startup circuit is here: https://www.downtowndougbrown.com/2015/03/explanation-of-the-macintosh-iiiix-power-onoff-circuit/

The computer won't be bricked when you pull these batteries out. In fact, it wouldn't surprise me if they both lost all their charge many years ago.

Correct, though it's worth clarifying that a Mac II needs both 3.6V batteries to be good in order to start.

 

[dougg3]

I find it really interesting to actually see one pictured that still has the original batteries on it! This is a good opportunity to discuss something I've been wondering about. One thing that was brought up in the comments on my blog (that joshc linked above) was that the original Mac II batteries were actually 3V rather than 3.6V. Of course, 3.6V batteries seem to work just fine too in everyone's experience. @amedeo_68k is there any way you can confirm the markings on the original batteries for the voltage? I think it would be useful for historical reference!

This old forum post seems to indicate the Varta "Ord No 6126" battery is indeed 3V -- I just can't see that part of the marking on those screenshots. Thanks!

Or, perhaps they were marked as 3V but were still actually 3.6V? This post was implying that...

 

[volvo242gt]

I find it really interesting to actually see one pictured that still has the original batteries on it! This is a good opportunity to discuss something I've been wondering about. One thing that was brought up in the comments on my blog (that joshc linked above) was that the original Mac II batteries were actually 3V rather than 3.6V. Of course, 3.6V batteries seem to work just fine too in everyone's experience. @amedeo_68k is there any way you can confirm the markings on the original batteries for the voltage? I think it would be useful for historical reference!

This old forum post seems to indicate the Varta "Ord No 6126" battery is indeed 3V -- I just can't see that part of the marking on those screenshots. Thanks!

Or, perhaps they were marked as 3V but were still actually 3.6V? This post was implying that...

Looks like the MH 13654 number supercedes to a CR123A battery. A two pack is $8.99, plus shipping (and tax, depending on state, etc) through Hunt's Photo & Video. https://www.huntsphotoandvideo.com/detail_page.cfm?ProductID=1916PRO&cid=8&manufacturer=Varta

 

[dougg3]

I got the feeling that the MH 13654 was a UL safety standards thing rather than a part number:

https://www.texim-europe.com/promotion/377/folder_lithium_cells_en.pdf

Safety: all cells are UL recognized under file BBCVL MH 13654

Avnet: Quality Electronic Components & Services

Avnet is a global leader of electronic components and services, guiding makers and manufacturers from design to delivery. Let Avnet help you reach further.

www.avnet.com

All Varta Microbattery Lithium Cells and Batteries listed in Table below are recognized by Underwriters Laboratories Inc. under UL-file number MH 13654 (N).

 

[volvo242gt]

I got the feeling that the MH 13654 was a UL safety standards thing rather than a part number:

https://www.texim-europe.com/promotion/377/folder_lithium_cells_en.pdf

Avnet: Quality Electronic Components & Services

Avnet is a global leader of electronic components and services, guiding makers and manufacturers from design to delivery. Let Avnet help you reach further.

www.avnet.com

Yeah, just looked. The correct part number for the 1/2 AA batteries is CR14250. Varta still lists it as being a 3 volt battery, just like how Union Carbide says the Energizer Ultimate Lithiums are 1.5 volt, yet, when you measure the voltage out of one AA battery, it's actually 1.8 volts.

 

[amedeo_68k]

@dougg3 Hi, The batteries are Ord. No. 6126, if you look at the picture, it is visible on the bottom battery.
However, While I would remove batteries, and recap the logic board, What I'm missing in the video board. It has been removed for some reason.

Thank you everyone for the infos !

 

[joshc]

@dougg3 Hi, The batteries are Ord. No. 6126, if you look at the picture, it is visible on the bottom battery.
However, While I would remove batteries, and recap the logic board, What I'm missing in the video board. It has been removed for some reason.

Thank you everyone for the infos !

If you can't find a video card locally, I probably have a suitable spare I could ship to you - it would be from the UK but probably not too expensive to post to Italy.

 

[amedeo_68k]

oh, that would be awesome, thank you in advance.

 

[LaPorta]

Two things: my II had them soldered in. They were both 3v, not 3.6v. I replaced them with holders. More interesting, I found push in 3v instead of 3.6v....and they work just fine!

 

[amedeo_68k]

@dougg3 Hi, while I was looking to remove the batteries on a Mac IIfx ( that have other issues on logic board ) I found a NuBus video card that should work in Mac II, I'll let you know.

 

[markkrueg]

I find it really interesting to actually see one pictured that still has the original batteries on it! This is a good opportunity to discuss something I've been wondering about. One thing that was brought up in the comments on my blog (that joshc linked above) was that the original Mac II batteries were actually 3V rather than 3.6V. Of course, 3.6V batteries seem to work just fine too in everyone's experience. @amedeo_68k is there any way you can confirm the markings on the original batteries for the voltage? I think it would be useful for historical reference!

This old forum post seems to indicate the Varta "Ord No 6126" battery is indeed 3V -- I just can't see that part of the marking on those screenshots. Thanks!

Or, perhaps they were marked as 3V but were still actually 3.6V? This post was implying that...

I saw your post and decided to record removal of my 36 year old 3V batteries from my original (board A) Macintosh II. Both are 3V batteries. One registered 3V and the other 3.8. Amazing after 36 years! Video in my thread:

Post in thread 'I am finally a Macintosh II owner again'
https://68kmla.org/bb/index.php?threads/i-am-finally-a-macintosh-ii-owner-again.44351/post-486448

 

[dougg3]

Wow, thanks for sharing! I'm amazed that they lasted that long! I'm also kind of surprised to see 3.8V on one of them...very interesting...

 

[amedeo_68k]

I think I have trashed the batteries, I'm going to check

 

[amedeo_68k]

oh, this is the Macintosh II, yeah, I have definitely trashed these, no need to go there to check. I was making confusion with the IIfx that I have elsewhere.However if I recall, these Varta soldered batteries are installed in Mac SE too.

 

[volvo242gt]

^They can also be found in early Apple IIgs machines, typically the ROM 00 machines. Most of the ROM 01 machines seem to have the Tadiran batteries.