Retro Repair - Repairing a leaked battery in the Amiga 2000 and more

[Retromat]

Greetings everone,

Ide like to report here about our small, ongoing journey about repairing the Amiga 2000 Mainboard from a leaking battery.
Let that said we are not even Semi Professional soldering people. We are hobbyists trying to save Old Hardware from dieing.
We sure are open to any hints you can give us.

We recently aquired a Amiga 2000 knowing it has a leacking battery and most likley damaging this machine for many manny Years.

Knowing that a big chunk of work awaits we decided to give it a go.

We made a Video of the first First Aid Actions we took cus of the Battery Leackage.


As you can see we stopped where we neutralized the most of the alkaline. (I know i say Acid in the video but thats a german thing, its called "Batterie säure" in german wich is translated as Battery Acid)

The Alkaline transformed the Solder into some strange metall alloy that was Resistant to any Heat we applyd (up to 450 C) and making unsolder the Attacked parts really hard.
If one of oyu might know the chemistry behind that i sure would love to hear it!

As you can see the Shiny solder turned into some Grey matter

Now we scrubbed up the solder mask with a special brush made out of fiberglass to take away all the damaged coating.


The damage of the Battery Liquid was crawling all trhough the CPU socket. As you can see a few traces got lost in the process as they where too damaged


We now replaced also attacked Capacitors and joined ...not really professionally but working, the traces with a wire together.


Ofcourse ide like to keep you up to date here finishing this to a Part 2 of the Project to save this Computer to make another video out of it to be uploaded on our channel.

Sidenotes:
We got rid of the old Soldering Iron of part 1, it was a spare one.
The board is a 2 layer board.

UPDATE 26.july

We did it! We repaired the amiga and its even working! I stated EEVblog in the video and the chemical description! Thanks guys!

[T3sl4co1l]

Probably not so much acid as alkali (potassium hydroxide solution), which can hydrolyze (break down, by introducing water molecules) many organics, and corrodes tin to potassium stannate (II or IV).  Probably copper is also corroded, more slowly, but especially if there is nitrogen present (making free ammonia, which attacks copper).  Hydroxide also absorbs CO2 from the air, forming the carbonate, a milder base that also dries up (whereas potassium hydroxide remains in liquid form because it absorbs moisture to form a solution, i.e. it is deliquescent).

Crusty deposits will be a combination of these salts.  They can be washed away with a mild acid.  Neutralize the acid with a mild base (e.g., sodium bicarbonate solution), then thoroughly wash the board.  Make sure the solution can reach all crevices in the board, including any layers that have been peeled apart by the corrosion (removing the soldermask accomplishes this).

After repairing traces, coat with tin plate for additional protection, clean rosin, then coat with soldermask again.

Tim

[dexters_lab]

yea looks like you've had a bit of a job there, great to see you have saved some vintage tech!

those rechargeable ni-cd batteries are just plain horrible, i just pulled one off an old 386 motherboard, thankfully there was only very minor pcb damage

[Ian.M]

See last years 486 motherboard rescue saga: https://www.eevblog.com/forum/repair/corrosion-removal-motherboard-with-leaky-nicd-battery/

Your Amiga board was in relatively good condition in comparison to that one.

You'll need a much better, temperature controlled soldering iron to have any chance of removing the corroded IC sockets so you can replace them, without damaging the board.  Carrying on using the iron in the video for desoldering is likely to result in severe board damage e.g. loss of through hole plating.   As Hakko clones like the Yihua 936 are very affordable, there's no excuse for using such a crappy iron when working on a valuable board.

[In Vacuo Veritas]

Glad we don't need shitty batteries like this anymore in our devices. What horrible little monsters.
I wonder why they didn't give the battery a wide berth on the PCB back then? Like, slap it on the board but don't route anything under it or near it. It's not like there wasn't room on something as huge as a 2000 board...
Maybe even route out a channel under the battery.
Hindsight. I love it.

[Retromat]

Thanks everyone! Verry nice insights! The chemical Reaction sure is  intresting!

Btw the funny thing is, the early Revs of this Amiga 2000 produced in Germany where soldered with a Capsuled Battery. I have one here where the battery leaked and it leaked all inside the capsule.
Later on as they moved the Production to the US whey started to go for cheap.

[Retromat]

UPDATE 26.july

We did it! We repaired the amiga and its even working! I stated EEVblog in the video and the chemical description! Thanks guys!

[james_s]

I fixed a pair of Amiga 2000's with similar damage a couple years ago, yours looks even worse though. Those batteries are awful, they're time bombs. The lithium PRAM batteries used in old Macs are even worse.

[BrianHG]

Man that A2000 was in bad condition.  I luckily caught my A4000 and A3000 leaking batteries around 6 years ago, just as they started to leak, yet, the acid just began to touch the PCB soldering right at the battery's legs and I was able to scrape away and flux clean off and place new batteries.  Thankfully, the machines still work and are corroded free.

[barbeque]

This is much worse damage than my A2000 had; I only had to replace the CPU socket and neutralize the worst of the gunk. Good job repairing it!

[eugenenine]

I picked up an old 2000 a couple summers ago and have found a couple bad traces but still get a green screen at boot,

What is the fiberglass brush you used called so I can find one

[Retromat]

actually its called .. "fiberglass pen" XD