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How to read this electronic component?

Discussion in 'Electronic Design' started by vd, May 10, 2007.

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  1. vd

    vd Guest

    I have a controller board for a treadmill that doesn't work. I see
    one component appears to burn out. It looks like a resistor. I want
    to replace this (de-solder and then solder back a new one). Here's
    what I see:

    --------------------------------------------
    | || 24 |
    ======= || C848 ==========
    | || |
    --------------------------------------------


    So, I see only 1 band of color which is grey (8) (shouldn't it be 3 or
    4). It could because the thing burnt out, and other colors
    disappear. There are are some other label:

    24
    C848

    The length of this (without the wire) is about 1/2 of an inch. The
    diameter is about 1/8 (or a bit bigger) of an inch.

    Could someone please tell me what type of components this is, and what
    is the rating for it?

    Thanks.
     
  2. mpm

    mpm Guest

    Looks like a diode, or maybe a surge supressor or some sort.
    Are you able to trace out anything it's connected to, or can you post
    a photo of it?
    That would help. (Someone here might recognize the numbers.)
    -mpm
     
  3. vd

    vd Guest

    Thanks, I'll post a picture of it when I get home. This thing has a
    cylinder shape. Most of the resistors I see at radio shack has a
    straight peanut shape (larger and round ends).
     
  4. vd

    vd Guest

    You're probably right. I found a page here:

    http://www.anatekcorp.com/faq/applianc.htm

    Which say a diode with label: ST; BZV; 47C; 24; C848 is a ST Micro
    zener, BZV47C24, rated 24 Volts, 5%, 2 Watts.

    In my case, the component may be a bit different (I'll have to double
    check on the underside of it).
     

  5. This is not a binaries newsgroup so find somewhere to post it, and
    provide a link here.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  6. vd

    vd Guest

    Thanks. I'll do that.

     
  7. vd

    vd Guest

    Here is the link to the images:

    http://vy.huy.ho.googlepages.com/treadmillcontroller

    The component is definitely the same as above: BZV47C24. So, I take
    the spec as:
    ST Micro zener, BZV47C24, rated 24 Volts, 5%, 2 Watts.

    Now, my question is how to get this component. I search on the
    internet and a few sites offer it, but they ask to buy in high
    quantity. I also wonder what other equivalent diodes out there that I
    can use, if I cannot find this component.

    http://www.mouser.com does not carry it.

    This site has it, but $250 minimum, and business buyer only.
    http://www.1sourcecomponents.com/partinfo/BZV47C24.htm
     
  8. (snip)

    You skipped a question. Why do you think you need to
    replace this component?
     
  9. vd

    vd Guest

    Looking at the board and the backside of it, I see the color on the
    board beneath the component brown/dark out. I assume it's burnt. I
    hope that after fixing this, there won't be more problem. However,
    you're right that this is not very scientific. Do you know you to
    trouble shoot thing like this without proper schematic diagram? Some
    chips appear to be impossible to test. I already take out this
    diode. I think I can test this by hooking it up to a voltage source
    serial with a resistor. If the electric flows (measure current), in
    both direction, that would be a bad diode. However, that only test a
    diode, not the board. I only have a digital multi-meter for this.
     
  10. This color change indicates that the component above
    operates at a high temperature. Zener diodes, especially
    multi watt versions, often operate at a temperature high
    enough to slowly discolor epoxy. It does not necessarily
    indicate the problem. Do you have a digital meter with a
    diode test range that you can use to test this component?
    No. There are some in circuit tests you can make with a
    digital multimeter, and some further component tests you can
    make by unsoldering some components, but without knowing
    what the board is supposed to do, it is difficult to trouble
    shoot why it isn't doing it.
    Yes, most diode failures result in a shorted junction. If
    you have a multimeter with a diode test range (indicated by
    a diode symbol) it provides a small current between the
    leads, and a millivolt indication of the drop across them.
    Most diodes will show 500 to 600 millivolts in the forward
    direction, and no reading (blocked current) in the other.
    To test a zener beyond that, requires that you apply more
    than the zener voltage, with a series current limiting
    resistor, while you measure the voltage drop across it.
     
  11. vd

    vd Guest

    Thanks for the reply. I tested and this diode is bad (it's open both
    directions). I am ordering another zener diode with 24V, but 5W
    instead of 2W. Would this be OK to replace a 2W?
     
  12. Almost certainly. The only difficulty may be getting the
    larger leads to go through the holes. You may have to
    solder a correctly sized wire in each hole, and attach the
    diode to those leads.

    As hot as the board got, I think I would mount the new one
    spaced a little bit above the board, maybe with a bit of
    heat sink soldered to each side of the body. This could be
    as simple as wrapping a n inch of wire once around the lead,
    and soldering it in place, so the two ends stick out into
    the air above the diode.
     
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