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Capacitor codes help

Discussion in 'Electronic Basics' started by Bryan Sembello, Aug 14, 2004.

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  1. 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:



  2. 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)?
  3. 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?


  4. 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

    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?
  5. Hal Murray

    Hal Murray Guest

    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.
  6. A dark band on an electrolytic capacitor is normally negative. To find out
    for sure, power it up and use a voltmeter.
  7. With the low working voltages, they're most likely electrolytics, and
    they are 47 uF and 100 uF.
  8. Rich Grise

    Rich Grise Guest

    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?

  9. 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

    A photo of the actual motherboard, so you can see what we're dealing

    Closeup of one of the caps (see the light-brown square plastic base I
    was talking about?):

    Another closeup of a cap:

    Photo of 2 of the (bad) capacitors, with top end bulging slightly
    (very subtle):
  10. Ray L. Volts

    Ray L. Volts Guest

    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
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