Static is [not] your friend - vacuuming PC?

I do it.

The frequency is limited more by my personal energy level than any fear of doing damage.

The first thing I do it just apply suction to any and all openings in the case. I have a fairly powerful vac (Kirby) and when it's applied to an opening with a fan (including the power supply) it spins up the cooling fans of the PC quite well!

I then open the machine and hold the nozzle with one hand and the chassis with another hand. I use shaped nozzles (e.g.: radiator cleaner) to get tight spots. If you guide the nozzle with your hand and fingers any static buildup will be taken away by your hand.

I "clean out" the interior openings in the power supply and the "other side" of fans, and ventilation openings. Then I take on the fan from the processor. I apply suction to both the top and the sides of the head sink and spin the little fan in both directions. It's amazing the amount of dust you get in there.

I go at disk drives with the same determination: if their is a hold, I apply suction.

It's not like you are charging up the vacuum nozzle and poking it wherever. It's mostly touching the chassis (or equivalent like +5 power). It's just not going to get the change to build up enough charge to blow out any junctions. I just don't believe the there is any IC out there that doesn't clamp inputs against very small amounts of charge transfer.

I believe that suction is less likely to generate a static charge than compressed air. In any case, suction gets the crap OUT OF THERE. Compressed air just moves it about.

The compressed air is just about as bad as the vacuum cleaner... maybe even worse in some ways.

Static charge on the nozzle is not the only problem. The buildup of static on the various components as a result of blowing dry air on them is just as serious as the nozzle (same source of charge!).

Both are relatively bad. However, if you do this when the relative humidity is higher than about 75%, it probably isn't all that dangerous. The vacuum cleaner's suction is indeed less of a problem than the forced air.

But if you do that when the relative humidity is 6%, and you'll be buying new circuit boards often.

Useful data! I have little doubt that a diskwasher can get boards extremely clean.

Ah, that helps a bit. Hypochlorite is nasty on copper (verdegris) and other metals. The other goodies will make for high pH, but that usually won't do more than frost over aluminum and zinc.

-- Robert

The key matrix is made of 2 separate flexible circuit boards attached together around the edges, similar to matrixes found in NMB keyboards, including the Microsoft Natural, and moisture can remain trapped between them. Normally you can remove those flexible boards and dry them out enough with 90%+ alcohol, but IBM put them between a hard piece of plastic and a sheet of metal "riveted" to together (ends of plastic rods melted against the metal), which traps the moisture even better. So you may have to cut off the rivet heads to get to dry out the key matrix and then replace the rivets with install washers and tiny screws.

Nope, a real model M is buckling spring, not mylar. Try the comp.sys.ibm.ps2.hardware group. Those boys are still patching up model Ms. I would bet the answer is no. You can take the cover off and wash ity anyway you want but there are lots of metal moving parts in the keyboard itself.

... snip ...

Isn't hypochlorite just plain fixer from the darkroom? Which required several hours of washing of prints.

You've gone just plain NUTS. I have to replace a few keyboards every month because some bozo spilled a bottle of Dasani water in it. Coffee is even worse. The little rubber dimples in the rubber pad collect the water, and they will *never* dry out unless you pull the keyboard apart and let it dry. And the cost of labor is greater than the ten dollars a new keyboard costs. And if you pull one apart, you may never be able to get it back together. Don't believe me? Try it sometime with a defunct keyboard! The really funny part of all this is the deviant behavior the user will display when you ask him or her if they spilled something in the keyboard. "Who, me? Never!" and I pick the keyboard up and the wter drips out of it. Yeah, right. >:-(

Floyd doesn't tell you but he lives in an igloo in a god-forsaken part of Northern Alaska where the ground is frozen all year long. His harsh cleaning methods aren't recommended and are a lot of hooey, IMHO, because the rag will damage the pins of the chips in a circuit board. It's insane to use anything but compressed air.

Nuts! Totally nuts! That's an excellent way to ruin it! You'll bake the circuit board!

Which is ALL the time where you live! You've gotta be _kidding_ with this post!

Actually I live in one of the most exciting places in the entire world. The name of the game is adventure, and there is never a dull moment.

Your remarks are interesting. Ten/fifteen years ago that was just about the only kind of response I'd get on Usenet from claiming one could just soak these things in plain old soapy water and get good results. But it isn't so common these days...

Of course I've been putting electronics into a dishwasher for 40 years now too (that right *40* years, which means it was electron tubes, not ICs). Which makes your protest just hilarious.

You might have noticed though, that for almost every instance of someone saying that compressed air is the right way, somebody else says use water. The fact is that water won't zap your circuit boards with ESD (and compressed air *will*).

Instead of flapping your jaw about it, you might do a little research on the subject. See if you can find out what the significance, for example, of water is for the pink anti-static material that you commonly see. And why it's pink.

Yer head's where the sun don't shine, son.

That is so ignorant that it is a joke:

Barrow, Wiley Post-Will Rogers Memorial Airport, AK, United States (PABR) 71-17-07N 156-45-57W 10M Weather reported at: Thu Oct 28 01:44:00 2004 AKDT ... Temperature : 12 F (-11 C) Dew Point : 8 F (-13 C) *Relative* *Humidity* : *85%* Pressure (altimeter): 29.63 in. Hg (1003 hPa)

--

Do you understand what 85% relative humidity is? It is rather

*normal* in a place that sits on a point jutting out into the ocean.

I thought "fixer" was sodium thiosulfate and some other stuff. Sodium Hypochlorite is laundry bleach and pool chlorine.

What's the RH after you've heated the air to, say, 68F? ;-)

Lesse...

Actual Vapor Density -------------------- = RH Saturation Vapor Density

At 14F (close enough) the saturation vapor density is 2.36g/m^3, so your actual vapor density is: .85 * 2.36g/m^3 or 2.01g/m^3

Raise that air to 68F (saturation density = 17.54g/m^3)

2.01g/m^3 -------- = 11% RH 17.5g/m^3

...seems pretty dry to me. ;-)

Floyd, I realize you've been unjustifiably flamed, but that is no reason to reduce your own credibility by misleading statements.

Yes, arctic outdoor air usually has high relative humidity. It has to be, otherwise the snow would sublime.

But that outdoor air is extremely dry in absolute terms. My psychrometric chart gives 5 grains water per lb dry air for

8'F dewpt. Heated to 60'F, that is 6.4% relative humidity. You're gonna need big humidifiers and all the fun they are to maintain (salt build-up, ugh!)

Furthermore, I suspect that static build-up is more a function of absolute humidity than relative humidity. Do people have lots of static problems in Phoenix summers?

-- Robert

...

...

You also have to realize that I didn't get off the boat here yesterday. And that *you* have little to no exposure to Arctic conditions and like a lot of other people your imagination is good, but doesn't match the reality of Arctic living nearly as closely as you think.

It doesn't????

Now we've had more than one person claiming the relative humidity in the Arctic is always low, and you claiming it is always high. I assure you all that it isn't *necessarily* either, and that in fact it is fairly easy to experience both conditions in the Arctic.

However, if you have *ever* experienced 6% relative humidity, you know that static just crackles out of everything. You can't move without generating a charge. Everything you touch gets zapped. You can't pet the cat, because it will run when you so much as look at it.

Now, I'm not going to figure out what's wrong with your calculations, but I have a cat and it jumps on my lap and gets petted with regularity. So far today we haven't had even one experience of enough static buildup to cause us to zap each other (at this temperature, it does happen, though not often).

You can be assured that the relative humidity inside my house is

*not* 6%, or anything close to it.

Which is to say, you don't have any experience with this at all, but you're willing to attempt definitive statements??? Tsch tsch.

I lived in Tucson AZ as a teenager. Trust me, in Phoenix they have *lots* of static problems in the summer!

I spent 20 years living near Fairbanks AK too.

In Fairbanks the relative humidity can be very low. (However, at the moment... it's 17F and RH is 91%!) But in Fairbanks there is no source for water vapor /and/ it is commonly -40C or colder. Fairbanks sits inland several hundreds of miles, right between two of the largest mountain ranges in North America; hence the relative humidity is commonly low, with no wind, and in the winter there are extreme cold temperatures on a regular basis. Static is a *big* problem when it gets cold, and only a small problem with it isn't that cold.

Barrow of course is a maritime environment, and with an ocean on three sides and with a constant wind there is no lack of humidity. The relative humidity for outside air is rarely ever very low, mostly because we rarely ever get extreme cold temperatures here (due to the moderating effect of the Arctic Ocean and the constant wind).

The effect is that in Fairbanks static is an almost constant problem, summer and winter, but in Barrow static is rarely a problem except during extremely cold weather in the winter (and virtually never during the summer).

Here are some interesting numbers. I've been archiving hourly weather summaries from NOAA since last winter. I don't get every hourly report each day, but in nearly 11 months have 6303 records. A quick grep produces the following numbers:

Total records: 6303 100% RH 354 90-99% 1588 80-89% 2256 70-79% 1872 60-69% 214 50-59% 18 40-49% 1

No records indicated less than 45% relative humidity.

I should probably point out that after 2 decades living in the Interior, I have a few habits regarding static that are useful. I use an anti-static mat on the floor and the table my computers sit on have a grounded metal strip running down the front, such that as I sit here typing, both of my arms are grounded.

And of course one of the reasons I advocate the use of water solutions with a wetting agent for cleaning circuit boards is because of the anti-static benefits (which include the effects of having a film of wetting agent left on the circuit board to help dissipate any static buildup, a beneficial effect that lasts for months).

Incidentally, if anyone can find information on how the ubiquitous pink anti-static plastic came to exist, the above reference to leaving a wetting agent on the surface of washed components has an interesting connection, historically. The idea of mixing a wetting agent into the plastic mix came as a result of observing that poly-plastic containers attracted less surface dirt when they were *not* rinsed clean of soap after washing. The same applies to computer motherboards.

That would indeed be pretty dry. Now, your next assignment is to figure out why the air in my house *isn't* that dry! ;-)

In support of that ...

Where I live (Moose Jaw, SK, Canada) isn't 1000+ miles further south than Fairbanks, but -30'C days are common during Dec, Jan, and Feb, and most years we get a few days of -40'C weather.

100% or near %100 relative humidity on days like that is nothing unusual - *outdoors*.

It takes trivial amounts of moisture in the air to cause near

100% RH at low temperatures like that. When it is -30'C and 100% RH, there is so little water in the air that if you heated a volume of that air up to room temperature the RH would fall to near zero.

However, except when guys like me do crazy overclocking experiments outdoors on a cold day, the outdoor relative humidity is irrelevant. It is the RH *indoors* that matters, and the colder it gets outside, the harder it is to maintain a sufficient RH inside. Warm air is constantly leaking out around doors and windows, up the chimney, etc, and carrying away lots of water with it. If the water is not replenished, such as by a humidifier mounted on the furnace, it is very easy to have a 20% RH indoors even when the outdoor RH is close to 100%.

Over the three coldest months of the year the humidifier for my tiny 800 square foot apartment goes through about 6 liters of water per day if I want to maintain a 40% RH. And that is over and above the humidity replenished by things like cooking, bathing, and simply breathing.

You only heat your house to 32F (RH=44%)? ;-)

Seriously, your washing of circuit boards isn't as silly as people here seem to think. The manufacturer washes flux off in what amounts to a dish-washer. I don't think I'd want to leave a soap residue though. Analogs certainly wouldn't like that much. A DI or distilled water rinse would seem appropriate.

BTW, that's first-aid for electronics (and even cameras) after being dropped in water. Take out the batteries immediately, then dunk in DI or distilled water as soon as practical. ...cook on low heat until done.

Great for my little digital hearing aid too. At $65 per incident there is no way I'm going to take it to the service center every time it gets a little sweat in it and starts making everything sound like exceptionally bad rap music. And at $2100 that hearing aid costs a lot more than most desktop computers do.

In the summer, after rinsing things like that they dry out quickly and safely if I lock them in the car for an hour or so on a sunny day :-)