Mac IIci Battery Bomb workaround - continuity points for new battery holder?

[gogopuffs]

This may be an easy one for you. I got a barn find battery bombed Mac IIci (Thank you @AppaloosaMac for the Mac Barn Adventure!) and I am pretty certain that it was stored for years vertically on its side, enabling the battery acid to pool on the side of the case and eat into the power supply metal instead of the traces on the board. Pretty lucky actually!

So, after a gentle clean, the thing boots and seems mostly happy, but definitely could use a recap as well. In addition to changing the caps, I'd like to put in replacement battery holder.

Two related things - are there a continuity test points (or alternately the correct RTC pin) that I can see if the battery vias are still viable (pun intended) and/or if they are not, would that test point be viable for a bodge wire to restore functionality?

RTC chip Pin 10 for ground (battery negative) or tracing over to the ground on the HDD power adapter and the leg of the D8 transistor?


Look at that beautiful (carnage) patina as I found it.


After a gentle cleaning and a zoomed out photo. You can see where that battery acid just ate up the metallic paint shielding on the inside. You can see how almost everything else looks perfect though.

Thanks for your help!

 

[zigzagjoe]

I had a similar issue with a Quadra 650 LB. It would not have been possible to solder a new holder as both holes for the holder had all copper dissolved, I instead fit a micro JST pigtail and used a common laptop CMOS battery from my junk box. It's worked well so far. Not original, clearly, but it gets the job done.

 

[Chopsticks]

This may be an easy one for you. I got a barn find battery bombed Mac IIci (Thank you @AppaloosaMac for the Mac Barn Adventure!) and I am pretty certain that it was stored for years vertically on its side, enabling the battery acid to pool on the side of the case and eat into the power supply metal instead of the traces on the board. Pretty lucky actually!

So, after a gentle clean, the thing boots and seems mostly happy, but definitely could use a recap as well. In addition to changing the caps, I'd like to put in replacement battery holder.

Two related things - are there a continuity test points (or alternately the correct RTC pin) that I can see if the battery vias are still viable (pun intended) and/or if they are not, would that test point be viable for a bodge wire to restore functionality?

RTC chip Pin 10 for ground (battery negative) or tracing over to the ground on the HDD power adapter and the leg of the D8 transistor?

View attachment 79759
Look at that beautiful (carnage) patina as I found it.


After a gentle cleaning and a zoomed out photo. You can see where that battery acid just ate up the metallic paint shielding on the inside. You can see how almost everything else looks perfect though.

Thanks for your help!

using your picture above as a reference the positive battery terminal connects to the top right pin on D8, and the battery ground can be connected anywhere that's convenient such as the top right pin of D7 or the right side of the C20 capacitor

 

[Chopsticks]

just noticed too it appears Y5 is missing the RTC needs that to run

 

[gogopuffs]

Ah, good notes, much appreciated to both of you who replied. I will try and seek out a replacement set of transistors when I get a moment. There is hope for that thing.

 

[Chopsticks]

D7 and D8 are actually diodes not transistors. i believe they are SOT23 packages, and just a generic signal diode like a 1N4148 or 1N914.
They are just used to stop voltage back feeding with the battery circuit so any diode similar to what i just mentioned should also work too.
if you cant easily/cheaply get SOT23 diodes you could just use a through hole packaged version in series with say a coin cell battery and bypass D8 all together.