Re: What's that black dust in monitors?

Jackie wrote

>> What is that fine black 'dust' one sees inside >> monitors when the case is removed? >> Just curious > Cooked skin mostly (carbonised dust).

Dont believe it. Its too fine for that and the distribution inside the outer case doesnt fit that either.

Reply to
Rod Speed
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** All the facts fit.

Electrostatically charged soot consists of very fine particles, follows air currents and sticks to plastic and metal.

.............. Phil

Reply to
Phil Allison

It's not caused by arcing or my Tesla coil would be covered in soot.

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Reply to
Vermin

On Fri, 19 Sep 2003 15:47:33 +1000, "Rod Speed" Gave us:

Actually, it is dust from your local region that collects any moisture in the air after it has been attracted to, and attached to whatever surfaces of whatever charged devices are in the monitor case. That would be the HV supply elements, and the tube itself. Then, all the chassis collects, because it is the return for some of the fields present. It takes on moisture and gains color. It isn't "baked".

This is why all military CRTs had fully potted HV supplies, and an oversized anode lead such that less corona is generated, and dust isn't as big a factor. Next to none on a supply that has a full faraday cage around it.

Reply to
DarkMatter

On Fri, 19 Sep 2003 16:05:17 +1000, "Phil Allison" Gave us:

It should actually read "sticks to charged surfaces". They are usually non-conductors, such as plastic, but conductors that are isolated from ground can gain charge, and become attractors.

Of course, electrostatically charged elements in a CRT monitor are the huge capacitive picture tube. Quite a field surrounds them.

Reply to
DarkMatter

** I was alluding to the chemical reactivness of soot particles - eg soot from a fire in a fibreglass PCB leaves dark stains on plated metal surfaces that cannot be removed with solvents.

........... Phil

Reply to
Phil Allison

** That may be so unless the air is full of photocopier toner particles - as when a busy office copier is sited next to the PCs. In the case I saw all the insides of the monitors and the PC's PSUs with coated in the black stuff.

........... Phil

Reply to
Phil Allison

Like the Tesla photo. Almost as impressive as this one...

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Reply to
CWatters

On Fri, 19 Sep 2003 17:01:37 +1000, "Phil Allison" Gave us:

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Reply to
DarkMatter

On Fri, 19 Sep 2003 17:05:22 +1000, "Phil Allison" Gave us:

Yes, and just like clean dry dust, it is a non conductive, dielectric even material that will be attracted to any surface that does not have a net zero charge.

Reply to
DarkMatter

Nope, dont fit at all. Particularly the distribution of that black soot on the inside of the monitor case.

It isnt even where the bulk of the airflow happens, so it cant be where the cooked skin ends up.

Yes, but it clearly cant be COOKED SKIN, and isnt where the airflow happens in a monitor either.

Its always quite close to the FBT, and so its coming from the FBT plastic.

AND its much worse in a monitor with a failing FBT which you know is failing because you can hear it clicking and you're getting the screen image changing when it does.

Reply to
Rod Speed

Correct, and you dont get that soot with those.

Its gotta be coming from the FBT, because its always on the case adjacent to that.

Cant be cooked skin either, but that area where the you get the soot in a monitor isnt usually where there is all that much airflow thru the case.

The source has to be the epoxy on the FBT.

Shit you're ugly, specially those red eyes |-)

Reply to
Rod Speed

Doesnt explain why its black soot.

You certainly get the effect you are talking about on the front face glass of the monitor and TVs, but its just dust colored.

You also get that effect with those ESD devices that claim to collect the fine dust out of the air so you dont breath it etc too.

That black soot you get inside a monitor case close to the FBT certainly isnt just dust, its black/very dark grey.

Nothing like the brownish/reddish dust we get so much of around here.

It isnt dust. Its much too black for that.

Reply to
Rod Speed

Sure but this is a red herring. Most home PCs dont have any photocopiers around at all, and you still get that black soot in all the monitors used in the home.

And its not cigarette smoke either. Thats got a characteristic stink to it so you can tell which PCs are used by smokers as soon as you open them. Presumably its the tars you are smelling.

Yes, but you still get that with monitors that have never ever been used anywhere near any photocopier.

Reply to
Rod Speed

Bet that annoyed the neighbors

Reply to
Vermin

Corse you would claim that now, dumbarse.

Reply to
Rod Speed

On Sat, 20 Sep 2003 04:57:21 +1000, "Rod Speed" Gave us:

That is also where the most field is. DOH! Follow the HV pathways, and generating element, and one will find where the most proliferant accumulations of particulate are. They don't come *from* the flyback, they collect around it, and other of the HV elements in the system.

Reply to
DarkMatter

On Sat, 20 Sep 2003 05:06:10 +1000, "Rod Speed" Gave us:

Yes. It is the tars that have accumulated on the dust that has accumulated on the charged surfaces inside the monitor.

A smoker actually reduces his CRT lifespan in his home for this reason. It blankets things such that they don't dissipate their generated heat as well, leading to pre-mature failure.

Reply to
DarkMatter

On Sat, 20 Sep 2003 08:03:50 +1000, "Rod Speed" Gave us:

Since we are in a High Voltage group, you are an idiot.

Reply to
DarkMatter

DarkMatter wrote in

Nope, not on the inside surface of the case it aint.

Using fancy words doesnt explain why you dont get a lot more on the FBT itself than on the inside surface of the case.

Pity the inside surface of the case doesnt qualify.

Reply to
Rod Speed

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