laptop power fault: compaq presario C300EA

There speaks someone who knows f*ck all about electronics. If you did, you'd know why electrolytic caps in a laptop is generally considered "A Bad Idea".

Without part numbers, it's meaningless.

Wrong.

Actually most laptops use tantalum polarized capacitors which are a type of electrolytic capacitor. What they avoid are the more common aluminum electrolytic capacitors. Ceramics are available in low voltages at quite high capacitance values, but I have yet to see one over 10 uF.

David

Beat me to it. Was just going to post a link to a piccy of a tantalum.

Nope. There are wet tantalum capacitors (that exist), but nobody uses those in laptops. In laptops you find surface mount dry tantalums among other solid types, not electrolytic at all... again, this refers to semi-modern laptops, not something really ancient.

ds

?? You have not indicated any electrolytic caps (but that's to be expected since there aren't any).

Other caps yes, but not electrolytic. I made that picture on a scanner, how high a resolution can you handle? Think these are 600DPI, roughly 6000x6000 res. so I'd recommend not trying to open them directly in a web browser. ~ 11MB Top Scan http://69.36.166.207/usr_1034/Top.jpg ~ 7MB Bottom http://69.36.166.207/usr_1034/Bottom.jpg

Caps yes, tantalum or other solid types like niobium. I suppose I should clarify that sometimes I'll see people calling solid capacitors, "solid electrolytic" but that is a misnomer, electrolytic implies a liquid electrolyte. Perhaps they really meant solid aluminum (can).

Practically all (on that example board scan) that aren't ceramic are over 10uF, none of which are electrolytic. Certainly years ago this would have been near impossible at any reasonable price, but great gains have been made in solid capacitors in the last 8 years or so, give or take.

snipped-for-privacy@insightbb.com wrote in news:d972e65d-ba83-4734-b5b7- snipped-for-privacy@k19g2000prh.googlegroups.com:

Take a look at the pictures.

Check your laptop and make sure you DON'T have any of the mugs in the shot.

If you are saying that 'modern' laptops don't have

The defining part that makes a capacitor an electrolytic is the presence of an electrolyte and the electro-chemical reaction that forms one of the electrodes in 'very close proximity' to the metal electrode which can be aluminum or tantalum or some other metal.

I used to make ceramic capacitors, so I am not really an expert on electrolytic but you seem to have a mistaken idea as to what constitutes an 'electrolytic'.

Any cap over .1 uF or so will probably be an electro.

Jerry

A tatalum cap is a type of electrolytic. Specifically the dielectric is formed by electro-chemical action.

Jerry

Considering the size it was probably a tantalum, which is a *type* of electrolytic capacitor.

Considering the Dell is by now probably 12 years old I'd say it's doing quite well.

Jerry

Nah, ceramics up to (and including) 10uF are common. I use bunches of 'em. There's quite an overlap (both have their use).

There are six visible in fz3.jpg

and four, possibly five in sf5.jpg

Those two are tants and I think the others are too !

There is a switch mode PSU in the first picture bottom right hand side along with its four caps and inductor !

d-polarity.jpg

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This is a good example of why we can't trust the encyclopedia that anyone can edit. The pictured caps aren't all electrolytic. The first two from the left are, and the rest are not (not 100% sure about the 2nd from the end on the right side).

Electrolytic requires liquid electrolyte.

There are types of wet tantalums that are electrolytic caps, but the solid tantalums are not. Where are these urban myths coming from?

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No. You can easily see on cap manufacturer datasheets that almost all chip caps are not electrolytic, and even ceramics now go up to 20uF. The chip tantalum, niobium, and other solid polymer caps you'll often find in laptops typically go up to about 470uF, there have been great strides in the past few years in this respect.

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Yes that's a great life for a laptop but at what point do you have to build your own battery packs because even the new stock is several years old stock?

It was not likely a tantalum, you do realize they explode, not vent, when shorted or reverse polarity? Not sure about the wet ones (probably not), but there's no reason they'd use something that exotic on the DC power inlet filter.

d-polarity.jpg

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Not electrolyte in the conventional sense of the word. While we could (and are) technically arguing about what constitutes an electrolyte, the majority of the capacitor industry is calling electrolytic caps those that have a liquid solvent. A few may have caused confusion because when they claim electrolytic they are not talking about the same thing, they are only referring to the manufacturing process in which they grow the oxide layer on the metal using electrolyte which is not put in the capacitor as a finished product.

snipped-for-privacy@insightbb.com wrote in news:58f338af-65bf-42a4-b96e- snipped-for-privacy@g3g2000pre.googlegroups.com:

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READ the article.

YOU are mistaken in your idea that electrolytics require a liquid electrolyte.

You will find that the essential action that produces an electrolytic is the formation of the dielectric 'oxide' layer by the electrochemical action.

There is no point in arguing over a definition. One either accept the commonly used definition and communicates with the world or insists on using a different definition and is frequently misunderstood.

If you look up "solid electrolyte" you will find that there are many compounds that are considered electrolytes that contain no water and some are even solids.

The SM chip left of C34 is probably an electrolytic, as are the two above the marking C518 on the topside picture. On the bottom, the two chips I mentioned before are just to the right and above the marking R678, another is above the marking 07/03/17 on the heat pipe in your bottom picture.

But we have wandered far afield of helping the OP fix the problem with his laptop.