Re: [NTLK] eMate chips

From: Andrei Chichak (acpmiedm_at_telusplanet.net)
Date: Tue Feb 15 2005 - 10:54:25 PST


At 10:59 AM 2005-02-15, you wrote:
>Thanks for the reply.

I think you're playing a bit beyond your level here...but...

> > At 04:58 PM 2005-02-14, you wrote:
> >> C109 ("the big yellow one") is a 100 microFarad 10 Volt electrolytic
> >> capacitor that you should be able to get in every Radio Shack
> >> store.=3D20

Capacitors store charge. They can do that by having a conductor near=20
another conductor, the two conductors separated by an insulator. Think two=
=20
sheets of foil separated by a sheet of paper.

Various capacitors use different conductors and different insulators.

An electrolytic capacitor typically looks like a cylindrical can. Inside=20
would be something like aluminum foil and an electrolyte (goopy acid).=20
These capacitors are polarized, they have a negative pole and a positive=
 pole.

A ceramic capacitor would have some sort of conductor separated by titanium=
=20
acid barium and have no polarity. They are encapsulated in ceramic.

Tantalum capacitors use a material called tantalum for the electrodes. They=
=20
are technically electrolytic but are encapsulated in ceramic. They are=20
polarized, so don't put them in backwards, they will explode. Tantalum is a=
=20
material that makes great capacitors that are very small and very stable.

There are also multilayer ceramic, polystyrene, polyester, polypropylene,=20
mica, and air gap capacitors, then there are super caps but that's another=
=20
story. Each has its own benefits and draw backs. Some are better at DC and=
=20
others are better at high frequencies. The usage depends on the application.

A surface mount capacitor is one that is soldered to the surface of a=20
printed circuit board instead of having wires that pass through the circuit=
=20
board.

> >
> > Not electrolytic, Tantalum, a surface mount tantalum.
>
>???? I have no idea what this means. Can you point me in the right
>direction so I can buy a replacement?

If you were to go to Radio Shack and ask for a 100uF 10V electrolytic=20
capacitor, they would give you something in an aluminum can that is 5mm in=
=20
diameter and 11mm high.

If you go to www.digikey.com and look up capacitors, there are zillions.

A 10V 100uF surface mount tantalum would cost $8.79 for 10. It is in a case=
=20
that is 3.2mm by 1.2mm and 1.1mm high. P/N 493-2353-1-ND

How big is your case?

See: http://dkc3.digikey.com/PDF/T051/0909-0926.pdf for more sizes. (18=20
pages of tantalum caps)

> > The Diode can be tested using a multimeter with a diode test function
> > (has
> > a diode symbol), with one probe on each end of D10 you should have
> > about
> > 0.6volts one way and reversing the probes, an open circuit. A dead
> > diode
> > would look like open both ways or some sort of voltage both ways.
> >
>If you are referring to testing the chips on the board to see if they
>work or not. If do not need to do that. They have incinerated on the
>board and I can look at them and tell they are bad. after looking at
>the prices on mouser it looks as if you can get these kind of chips for
>less than $1 each. which would put the repair and $4 + shipping, much
>less than a referb eMate. I also do not want to see this end up in the
>trash, call me sentimental. What I do not know is what they are
>exactly so I can purchase replacements. I can use a soldering iron but
>do not know about electrical engineering.

It sounds like, by the types of components that are cooked, that someone=20
put a power supply with the wrong polarity on.

>I was hoping that some of the extremely knowledgeable

Nope, you just have us.

>of the list would
>take pity on me and illuminate my ignorance in this matter e.g. tell me
>what these chips are and where to get replacements.

Digikey is good, a bit more money but the prices include delivery and they=
=20
are quick. Mouser is good, but the parts can take a long time to get to=20
you. Radio Shack has what they have and you better know more about it than=
=20
they do.

Andrei

-------
Andrei Chichak #200 10835-120 Street
Senior Software Developer Edmonton, Alberta
Pulmonox Medical Inc. Canada
                              T5H 3P9
                              (W) (780) 451-3660
                              (F) (780) 452-0169

Lat: 53=B0 33' 13.548" N
Lon: 113=B0 31' 43.164" W

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