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My wife was having dinner in front of (on top of) the laptop and she spilled some soup onto it, right above the touchpad. Almost all of the soup ended up in the upper DIMM slot which sits underneath the keyboard.

I took the laptop apart and I've managed to clean and dry everything other than the internals of the DIMM slot. The slot has a dense, comb-like structure of pins which holds the greasy water in, and I cannot disassemble the DIMM slot in order to clean it thoroughly.

When I turn on the laptop it detects all available RAM and it works normally for about 15-20 minutes, after which it turns off. When I try to turn it on again it emits 1-3-3-1 beeps which means "Bad DIMM or DIMM slot". If I then take out DIMM chips, wipe them and clean the slot with a toothbrush it works again for a short time. I suspect that when the laptop heats up the grease in the DIMM slot melts a bit and short-circuits some pins inside.

I was wondering would it work if I used WD-40 with a straw to fill the DIMM slot, and then dry it with paper towels and a fan? The WD-40 should dissolve the grease and it dries faster than water, I'm just not sure whether after drying it leaves any conductive residues which would cause a short circuit inside the slot. Or is there something else I can try? Any thoughts and ideas are appreciated.

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What type of laptop is this, so that I might avoid it? Any well-engineered laptop should channel spilled liquids away from critical components, not into them. Even cheap $10 keyboards are designed to channel liquids in a safe manner. –  dotancohen Jul 2 '14 at 10:47
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You can't expect an electronic device to work if there is standing water in it. Please don't use WD-40 it won't solve anything. Besides...A short circuit likely would cause permenant damage to the circuit. –  Ramhound Jul 2 '14 at 11:10
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Please don't turn it on again until it is completely clean and dry. You're extremely lucky if your attempts at powering it up so far haven't destroyed something permanently yet. –  Bob Jul 2 '14 at 12:06
    
Maybe a small amount of isopropyl alcohol mixed with lots of distilled water? (disclaimer: never tried this on a real laptop, but I did bathe a motherboard in distilled water at one point and it worked for years afterwards). –  romkyns Jul 2 '14 at 14:25
    
@dotancohen: It's a Lenovo T520 - I know, it should be better than that... –  Boris B. Jul 3 '14 at 8:08

3 Answers 3

up vote 31 down vote accepted

When it comes to slots and other hard-to-reach places on electronic boards, I often use a combination of IPA cleaner and compressed air. It is easy to damage pins inside the slot by using toothbrush or a toothpick. Just spray it well with IPA, give it a gentle wipe and then give it a good blast with compressed air aiming directly into the slot. You can repeat the operation more then one time to achieve better results. You can buy both IPA and compressed air cans from ebay relatively cheap.

In regard to your idea of using WD40. I don't advise you to do that. From WD40 page on wiki:

The long-term active ingredient is a non-volatile, viscous oil which remains on the surface, providing lubrication and protection from moisture

You don't want to lubricate connectors on your motherboard. Even though multiple sources on the Internet say that mineral oil contained in WD40 is not conductive and it is often used to clean contacts in automotive industry. It is not suitable for computers. You will get problems with dust and grease buildup on oiled contacts.

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Just a note on the mineral oil - Some have submerged entire operating motherboards in a tank as a cooling method. I wouldn't do it, but it is non conductive. youtube.com/watch?v=PtufuXLvOok –  Carl B Jul 2 '14 at 19:47
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WD40 is also known to dissolve/soften some materials over time, I read a good article about it a while back on why you should NOT use use WD40 on electrical gear. Unfortunately I've got no idea where the article was so can't give a link. Anyway, use IPA or proper electronic PCB cleaner on electronic gear and DO NOT power it up till it's dry (as in, leave in airing cupboard for 24 hours). –  John U Jul 2 '14 at 20:35
    
@Carl B "it is non conductive" - neither is water. However I'd avoid spraying mineral oil on my components for the same reason water can cause issues - impurities. –  NPSF3000 Jul 3 '14 at 4:51
    
@NPSF3000 - water is very conductive...just to note. :) –  Carl B Jul 3 '14 at 7:12
    
I've spent the entire of yesterday's afternoon trying to find IPA in retail stores and pharmacies. They either didn't have it or didn't even know what it is. :) –  Boris B. Jul 3 '14 at 8:21

I had a similar problem removing grot from an SD card slot. WD40 is not the answer! The best stuff I know of for cleaning electronics is IPA (Isopropyl Alcohol) which is the same stuff used on some screen wipes. Its great for cleaning flux from circuit boards, but also gets off grease and oil quite nicely too.

Wrap a toothpick in a layer of kitchen roll or something similar, add a bit of IPA to it and then gently rub that in and out of the socket between and on the pins - try not to go side to side so as not to bend any of the pins. You may need to do it a few times with clean bits of kitchen roll as the old piece gets grotty. Once satisfied, wait for a couple of minutes for the IPA to fully evaporate and then put the memory back in and try again.

You should probably also clean the contacts of the memory board as well with IPA/kitchen roll, just to make sure there is no residue left on that. (Observe static precautions, ground yourself while working on the electronics).

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IPA is an excellent choice - a good solvent (it will dissolve the oils from the soup nicely), but not so good it will start dissolving the plastics on the motherboard (which something like acetone might do). In place of a toothpick, you might try a popsicle stick - it's a little wider, so you can clean more pins at once - or a q-tip. –  Kryten Jul 2 '14 at 16:42
    
IPA is unlikely to dissolve anything on a circuit board as it's very commonly used as a PCB cleaner. –  John U Jul 2 '14 at 20:44
    
@JohnU that's what Kryten is saying: IPA is a good solvent for things like grease and oil, but not so good that it would dissolve components. –  Doktor J Jul 2 '14 at 21:10
    
Ah, yes, mis-read that one. –  John U Jul 3 '14 at 9:20

What I do is pull the board out completely and take it to my workshop where I hook my degreasing gun to my compressor, turn the pressure down to 200kPa and blow the water out.

Once it looks dry I load the gun with IPA (isopropanol as mentioned by others) and repeat. IPA is hydrophilic and will get the last traces of moisture out.

For coffee or worse cola spills I might start with the IPA, cola in particular is nasty.

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It's not really easy to take a laptop's motherboard out, and not recommended if you don't know what you are doing. Might also void your warranty. –  Seth Jul 3 '14 at 12:46
    
Quite so. It's also not recommended to spill your drink on it. If you think people should try the easy, low risk options first, then I agree with you. –  Peter Wone Jul 15 '14 at 4:42

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