Capacitor codes help

Hi! I have some surface-mount capacitors I need to replace. I don't
really understand the codes on them, despite looking up many sets of
SMD capacitor coding conventions on the net. Is the first number the
capacitance value or is the second number? If someone could help
decipher the values, I'f be very grateful. Thank you in advance.
One of them has this printed:

h3
47
16V

Another:

14
100
6V

 

In these cases it looks like the second number is the capacitance (in uF)
but I can't be sure. Are these tantalum capacitors (relatively high
capacitance, with a positive end marked)?

 

I was thinking the second number is the capacitance also, but I wasn't
sure if possibly the first number is a multiplier for the second
number. These are small, silver-coloured, cylindrical components
apparently with an aluminum casing, about 1/4-inch in diameter and
about 3/16-inch tall, having a thin, square plastic base and soldered
directly to the surface of the board. There's a gray band striped
down one end of them, on the top, where the numbers are. (Is this
negative or positive?) Regarding the capacitance, I can't be sure
until I understand how to read the numbers.

I'm replacing these because they're on a motherboard which has
power-up/boot issues which have been gradually worsening, and some of
these capacitors have bulges in the top of the casing. Doesn't this
only happen with electrolytics, when the electrolyte fluid dries up,
becomes a gas, and expands from the heat?

Thanks!

 

From your description it seems highly likely that they are aluminum
electrolytics, and that the second number is the capacitance (in uF) and the
third is the voltage.

Replace the caps with ones rated for 105C temperature - they'll last a bit
longer.

I'm not sure which side the gray band is - I've seen both, in practice. Can
you get at one of them with a voltmeter, when the power is turned on?

 

h3
My guess would be 47 uF at 16V and 100 uF at 6V

You can get some sanity checking by finding a data sheet
for a similar part and checking that those values come
in the size cans that you have.

If you get lucky, you will find a data sheet that
explains the marking that you have.

 

A dark band on an electrolytic capacitor is normally negative. To find out
for sure, power it up and use a voltmeter.

 

With the low working voltages, they're most likely electrolytics, and
they are 47 uF and 100 uF.

 

Yes, and I've seen tantalums where the positive was marked, but his
description does sound like aluminums. But with the square base? It's
the first time I've ever heard of a cap with a square base. Are you
sure they're not transformers?

Thanks,
Rich

 

Hi! Thanks to everyone who sent suggestions -- I guess it's pretty
safe to say at this point that they're aluminum electrolytics,
47uF/16V and 100uF/6V. But it's pretty clear that my description of
their physical characteristics wasn't sufficient, so I took some
photos:

A photo of the actual motherboard, so you can see what we're dealing
with:
http://webpages.charter.net/toastydropbox/p6400caps/p6400-alchemy-mb.jpg

Closeup of one of the caps (see the light-brown square plastic base I
was talking about?):
http://webpages.charter.net/toastydropbox/p6400caps/smd-cap1.jpg

Another closeup of a cap:
http://webpages.charter.net/toastydropbox/p6400caps/smd-cap2.jpg

Photo of 2 of the (bad) capacitors, with top end bulging slightly
(very subtle):
http://webpages.charter.net/toastydropbox/p6400caps/smd-cap3-bad.jpg

 

Standard SMD (aka "chip") caps. Used by the truckload in camcorders.
Sometimes these lytics are identified by a code with a letter denoting
voltage and 3 numbers (2 digits and the multiplier) being the value.

The last pic clearly indicates the "+" terminal of C69 (C59's + terminal is
a bit harder to see). So you now know for certain the black edge is the
negative terminal -- it almost always is with these.
The "h3" is most likely a series (or possibly plant) identifier for that
production run.

Here's another way they ID these things (note also the lot number
identifier):

http://industrial.panasonic.com/www-data/pdf/ABA0000/ABA0000CE88.pdf