Macintosh II revision I've not found reference to

[wottle]

I picked up a Mac II recently and was looking to do a recap. However, the board markings show a number different than what I can find reference to online.



It seems to be very similar to pictures I've found of the 820-0163-02 board in terms of capacitor location. One difference I did notice that I haven't found in any pictures is that the PRAM batteries are installed in holders on an additional board that has its own 1000uF capacitor. Anyone else have this? I'd like to remove the PRAM batteries and replace them with batteries that are less likely to leak and also move them away from the main board for safety. However, I don't want to mess up that board if it is rare or provides different functionality the old soldered in batteries.


Anyone else have a Mac II with this setup?

 

[Phipli]

It seems to be very similar to pictures I've found of the 820-0163-02 board in terms of capacitor location.

An numeric based rev usually means it is a prototype I think. I would expect your board to be a standard Rev B? What is the board serial number, that would be more informative.

One difference I did notice that I haven't found in any pictures is that the PRAM batteries are installed in holders on an additional board that has its own 1000uF capacitor. Anyone else have this?

This was a standard aftersales mod. A lot are like this.

Edited because I had alpha / numeric backwards.

 

[dougg3]

It's referred to as the "Battery Holder Board" in the service manual.

 

[ktkm]

"Battery Holder Board"

Nice! That explains it -- FYI mine had soldered in batteries.

 

[olePigeon]

Interesting. So the battery holder board could have been a factory mod.

 

[ObeyDaleks]

What function does the capacitor serve in the aftermarket mod? I assume it’s just for load regulation?

 

[LaPorta]

To keep current while the batteries are changed.

 

[wottle]

Awesome information. I saw it was an Apple part, but apparently not too many people opted to install it based on online image searches. I'll likely remove it and replace it with a battery holder and wires to get the batteries away from the logic board.

 

[Phipli]

Awesome information. I saw it was an Apple part, but apparently not too many people opted to install it based on online image searches. I'll likely remove it and replace it with a battery holder and wires to get the batteries away from the logic board.

If you just replace them with coincells they almost never leak.

 

[wottle]

If you just replace them with coincells they almost never leak.

True, but the coin cells go dead pretty quickly, and the Mac II seems to be pretty sensitive to power. I also don't want to have to remove the floppy / HD tray to access it when they need changed. I have a non-working Mac II that I did replace with AAA battery holders and I attached them via long enough wires and can turn the batteries on / off as needed. I put in rechargeable as in my experience they have a much lower chance of leakage. And if they do, they are in a plastic case so I should have longer to figure it out and remove them before the leakage escapes.

 

[Phipli]

True, but the coin cells go dead pretty quickly, and the Mac II seems to be pretty sensitive to power.

I've had coincells in macs for over a year and they're still fine.

I also don't want to have to remove the floppy / HD tray to access it when they need changed.

You can reach them if you unplug the SCSI cable.

But it is up to you, I've gone with coincells in the machines I use most.