Trying to find replacement for cap with mysterious codes

Discussion in 'General Electronics Chat' started by MasterSnow, Jan 15, 2010.

  1. MasterSnow

    Thread Starter Member

    Jan 18, 2009

    A piece of equipment of mine recently had a SMD tantalum capacitor blow. Unfortunately, said capacitor appears to have been made by ST Microelectronics, who doesn't seem to make capacitors. :confused:

    Since I can't seem to make heads or tails of this, I am humbly submitting this data in the hopes that maybe someone can enlighten me. :)

    The code reads as follows: E

    If it helps, the capacitor is approximately 7mm x 4mm along its length and width, including its SMD contacts.

  2. bertus


    Apr 5, 2008

    Can you make a clear photo of the parta and paost it?

  3. MasterSnow

    Thread Starter Member

    Jan 18, 2009
    I tried and tried, but unfortunately no camera that I have can focus on the tiny capacitor enough to make out anything. :( I suppose I could try and describe it in detail.

    As I said above, it is approximately 7x4 mm. If we have it oriented so that the markings on it are right side up, the line indicating that it is a polarized capacitor is vertically to the left of the markings traveling up the width of the package. Starting at the top and reading down, there is the ST logo, then the E. Next line is BUX. Bottom line (the three lines of text pretty much cover the entire area of the package top) says C440. The package is black and the text is a brownish color.

    I realize that that description is probably ridiculous and unhelpful, but who knows. At this point I'm wondering if these codes are proprietary to ST micro, as they don't seem to make sense in the context of any capacitor code I can find for tantalum caps. And like I said, ST doesn't seem to make them any more best I can tell.

    Thanks for your time!
  4. Externet

    AAC Fanatic!

    Nov 29, 2005
    Is there any markings in the board where it came from, as "C52" or "CR8" or "D19" ?

    By looking at other capacitors with the same size, you may tell its capacity. If you know the voltage of operation at that node, it makes it easier to discern.
    It may be a diode.
  5. MasterSnow

    Thread Starter Member

    Jan 18, 2009
    Thanks for your insight Externet! I feel like a moron for not having considered that myself. Apparently it is a diode of some sort - Googling the number and the word diode brought up a plethora of discussion on the subject on other forums.

    Apparently, the E means that the device is lead free. BUX is the part identifier. C is the place of manufacture. The first 4 is the year of manufacture, and 40 is the week of manufacture. I still can't find any exact info on the BUX part, however. The only part that ST seems to have with that designation is a series of discrete BJT's...which can't be right as this is obviously a two terminal device.

    Thanks again for the help!