I don’t really like the baking soda idea as you are introducing contaminates to the board that may not fully wash away and aren’t electrically inactive. I used to repair gas ranges and customers would render them inoperable with commit, and baking soda. Sometimes it was very hard to get all of it off the sparking system.

Vinegar, soap water, tooth brush, few isa insertions, vinegar, soap, water, rinse, blow it out with compressor, hair dry it, set it out to dry.

The biggest concern with the battery alkaline is copper traces it will literally destroy them. It doesn’t usually affect resistors, diodes, etc. but they can become unsoldered/contaminated and hard to resolder.

Agree ! Distilled white vinegar 5% is best though a bit slow at eating the leakage of old PC batteries (is not acid but base like sodium hydroxide). Try a gental tooth brush and scrubb a bit if you see goo.
Have seen resistor packs (those 6x or 8x 100ohm or 330 ohm type) get their leads rusted from "battery acid" and cause issues but not individual resistors much....
Post a picture of the best board (not the worst as it may be beyond repair... it happens).
added: also some resistor packs have plain steel leads not tinned, and those can rust with just water....so after rinsing with water make sure to blow dry (but not with some 100lbs+ air compressor 🤣)

I use citric acid, works great. Since you’re in NL you could try this:
https://www.kruidvat.nl/hg-citroenzuur-koffie … kalker/p/648620

Naval Jelly. It's gel so it sticks to the pins and won't just run down into the connector. Paint it on with a small watercolor paint brush.

Kouwes wrote on 2024-03-17, 06:43:

I use citric acid, works great. Since you’re in NL you could try this:
https://www.kruidvat.nl/hg-citroenzuur-koffie … kalker/p/648620

Citric acid is great for oxide removal, but regrettably it leaves solid residues when it dries up. Acetic acid evaporates completely, which is an advantage when using it where it might be hard to flush or remove all of it mechanically.

That being said, I personally prefer to avoid using acids or bases on electronics if possible. I'd try gentle mechanical cleaning with some contact spray (Deoxit, 2-26, Oxide Clean and Protect, etc) and a toothbrush first. An old credit card wrapped with a lint free cloth is useful for polishing the contact surfaces, just insert/pull it as you would an ISA card repeatedly. Once you've removed the oxides, you can flush it all with some quickly evaporating electronics cleaning spray that leaves no oily residues. Compressed air is useful too if you have it available.

Thank you for the replys so far.

I'm not going to answer everyone individually.. But i red all what you have posted.

So far i can tell i used cleaning vinegar 8% (not the kitchen vinegar)
Also used a dental tooth brush from a good brand.

After that treathment i see 2 hours later iam guessing (didnt watched the clock)
I rinsed the boards off in the sink and used some dish wash soap.
I know it didnt removed flux or such stains, but it helped to remove the dirt / dust from the boards.

If you say that baking soda isnt a good idea they i think i wont try it out.

If there is still some contamination left that wouldnt hurt iam guess, because it would also getting a rinse with a bath of Isopropanol Alcohol 99%.
In the state the boards in right now i never wouldnt power them up..

Iam also going to use Deoxit D5 also.. But iam looking more in to getting of the green stuff of the isa connector pins.. If i can save a lot of those pins, i dont have to interchange them all for some other good pins.

Iam already have planned to get the targeted dirty isa slots off, and will push the unrecoverble pins out and replace them with clean ones, from a donor.

Kouwes wrote on 2024-03-17, 06:43:

I use citric acid, works great. Since you’re in NL you could try this:
https://www.kruidvat.nl/hg-citroenzuur-koffie … kalker/p/648620

Wouldnt that citric acid remove the gold plating on the ISA connector pins?
If i get blank pins back, then i wouldnt use it.

The other option would be desolder the targeted isa slots. Remove al the connectors pins and cleaning them seperately.

Robin4 wrote on 2024-03-17, 14:45:

Wouldnt that citric acid remove the gold plating on the ISA connector pins?

Gold is used for contact points because it's not very chemically reactive, which means the surface will not corrode due to oxygen or mild acid or base contamination. The problem is gold is expensive, and too soft, so it's only a layer over some other metal like copper or brass. Obviously to keep the prices low everyone tries to use as little gold as possible, and the process might be rushed too, so you end up with thin, possibly uneven (tiny gaps) layer that is especially weak on the edges.

In other words, the corrosion you have is not on gold but on the base material, and possibly the growing salt crystals already displaced some of the gold anyway. A weak acid like citric is not going to damage pure gold. Impurities and the base brass is another story but even then it would take days or more of constant exposure to do any serious damage.

In general chemical cleaning is less damaging if you can apply mild chemicals in a controlled manner and then clean it all up - which is the difficult part. Mechanical cleaning on the other hand risks damage to the gold layer as the first thing, since it's soft. In the end you'd probably want to find some middle ground, using chemicals that are diluted and easily washed away with water, but some mechanical cleaning before and after will help remove the salt buildup so that you can use less aggresive chemistry. And if it's really bad then slot replacement is the only option.

Robin4 wrote on 2024-03-17, 14:45:

Wouldnt that citric acid remove the gold plating on the ISA connector pins? If i get blank pins back, then i wouldnt use it. […]
Show full quote

Kouwes wrote on 2024-03-17, 06:43:

I use citric acid, works great. Since you’re in NL you could try this:
https://www.kruidvat.nl/hg-citroenzuur-koffie … kalker/p/648620

Wouldnt that citric acid remove the gold plating on the ISA connector pins?
If i get blank pins back, then i wouldnt use it.

The other option would be desolder the targeted isa slots. Remove al the connectors pins and cleaning them seperately.

You can still buy new ISA connectors for cheap from places like Mouser. I've used them for projects. Not worth depinning and cleaning. If you're gonna desolder, just replace it.

kingcake wrote on 2024-03-17, 23:49:

Robin4 wrote on 2024-03-17, 14:45:

Wouldnt that citric acid remove the gold plating on the ISA connector pins? If i get blank pins back, then i wouldnt use it. […]
Show full quote

Kouwes wrote on 2024-03-17, 06:43:

I use citric acid, works great. Since you’re in NL you could try this:
https://www.kruidvat.nl/hg-citroenzuur-koffie … kalker/p/648620

Wouldnt that citric acid remove the gold plating on the ISA connector pins?
If i get blank pins back, then i wouldnt use it.

The other option would be desolder the targeted isa slots. Remove al the connectors pins and cleaning them seperately.

You can still buy new ISA connectors for cheap from places like Mouser. I've used them for projects. Not worth depinning and cleaning. If you're gonna desolder, just replace it.

Yeah i know, but like to keep the isa slot as original as possible. These slots for older suntac boards are hard to find..