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Clean PCB´s with oxidation and saltpetre

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2PAC Mafia

Member
Hi guys,

I have electronic units from a boat which was under water. Boards now are in bad condition and I would like to know which chemical products you recommend for cleaning them the best as possible. Thanks.
 
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ericgibbs

Well-Known Member
Most Helpful Member
hi,
First use warm water with added detergent, say pot washing liquid, then rinse thoroughly with deionised water.
Allow to dry, a woman's hair drier used carefully will increase the drying speed.

Inspect for for any copper track or wires which are 'green' with verdigris, clean and reconnect any broken tracks.

Plug in for a few seconds , [protect your eyes with safety glasses].

E

Let me know the outcome, if the unit survives a power on period of a few minutes, there is a further TLC job to be done.

EDIT:

If the size of the unit is smallish, use a plastic bucket to immerse the unit in the soapy water.
 
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tomizett

Active Member
I agree with the above; water and detergent followed by a good rinse seems to do as good a job as anything. I generally follow that with a wash with isopropanol to remove any organic contaminants that aren't soluble in water - but given that your boards have been in the sea, there's not likely to be much benefit in this.
You can also use compressed gas/air to blow off the excess water before drying, to speed the process further.

I thought I had to deal with some pretty filthy boards in my professional life, but I've never had to revive something that's actually been in the sea. Although I did once have to overhaul a dimmer unit that had been urinated into by a builder...
 

ericgibbs

Well-Known Member
Most Helpful Member
hi tomiz,
As you can see from from my profile, I worked in the Hydro-graphic surveying industry.
You would be surprised by the number times equipment gets dropped into the sea/river when working on smaller boats, as well as boats sinking.

The above method sounds crude, but in most cases it works.
Many of the recommenced cleaners are too aggressive and can cause further damage.

After the unit is cleaned and retested OK, its important to apply a protective film of light oil on surfaces and contact pins.
and regular visual inspections.

E
 

tomizett

Active Member
To be honest I'm proably as interested in hearing about your methods and techniques as 2PAC is, given that cleaning forms a significant part of my day-to-day work.
I've been moving towards using water more and more - it raises some eyebrows sometimes but, as you say, there's no chance of damage by agressive solvets and it leaves no residue.
I must admit that we don't use de-ionised water yet, although it's crossed my mind that it would be the the ideal option. How significant would you reckon the benefits are?
Also (and 2PAC was probably going to ask this as well), do you have a light oil in mind that you'd recomend? I generally use Servisol Super 10 on larger connectors, and Deoxit gold on the more delicate gold plated connectors.
 

ericgibbs

Well-Known Member
Most Helpful Member
hi tom,
The final rinse using deionised water is that it free from dissolved solids and so when it dries does not leave a streaky finish.
I use a aerosol lube spray, that can be used on connectors.

What sort of equipment do you get that requires cleaning.?

E
 

tomizett

Active Member
I do service of professional audio and lighting equipment. A major contaminant is the fluid from smoke/fog machines - this is mostly oil based, and in turn traps dust and fluff from the air. Most of the stuff uses forced air cooling, and so picks up anything that's in the atmosphere.
Of course we also get spillages of drinks in things like mixing consoles, and occasional rain water damage from outdoor events.
 

2PAC Mafia

Member
Thanks, guys, I tried your recommendation today only with one board, not the worst one, (there are many) but it didn´t work, it seems the boards were too much time on salt water... :(

The only solution I see is removing all the components to clean the PCB´s (under IC´s) and IC´s (replacing some of them) but this would be a very hard and risky job because also the tracks (all multilayer) can have problems.

Now next step is to find a good and simplest way to manage the marine engines as my customer can´t assume new original equipment. The marine engines use a Bosch 24V injection pump, attached. Any good ideas? I have some idea but I don´t know if I´ll finish this project due to different reasons.
 

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