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Need to ID another SMD part...

Discussion in 'Misc Electronics' started by Don Bruder, Nov 14, 2003.

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  1. Don Bruder

    Don Bruder Guest

    Still playing with the lightning-hit modem from the other day. Have
    tracked traces to a component I can't ID, and am unable to get any kind
    of useful meter reading from.

    Approx 6.5mm long, slightly less - perhaps 4.5-5mm wide, < 2.5mm thick.
    Solid black body with silver/grey-ish markings. Two protruding tabs, one
    on each short side, bent down to make contact with solder pads on PCB.


    | Approx |
    | 6.5mm |
    | |
    | |
    V V
    -------- <------
    | St | Approx
    || BHH || 4-5mm
    | C638 |
    -------- <------

    Other (possibly) helpful commentary:
    The "St" is obviously a logo (and maddeningly enough, one that I
    recognize, but can't put a company name with) with the top of the "S"
    joined with/forming the crossbar of the "t", all done in "inverse
    video", if you follow my meaning. A notation silk-screened on the board
    near it (may or may not be related to the part, but because of its
    position, I think it probably is) reads "TVS1".

    Anybody know what this "little black box" is? I can get no reading out
    of it with my meter set for ohms, in any range, in either direction -
    Meter behaves as if it isn't connected to anything. Whether this is
    normal for this part (TVS1 = "Transient Voltage Suppressor #1", perhaps?
    Sorta like a MOV?), or a symptom of it being fried is a complete unknown.

    Google gives me nothing that makes any kind of sense on "C638" or "BHH",
    and I expected (and got) too many hits to even TRY wading through on
    "St", most dealing with - you guessed it - catholic saints, but none (of
    the 6 pages or so worth of results that I bothered flipping through)
    related to electronics.


    And in the spirit of "teaching me to fish" instead of just giving me
    one, if you know what this critter is, it would be appreciated if you'd
    enlighten me as to how and/or where you found the information.

  2. -------- <------
    ST Microelectronics (SGS-Thomson).
    You guessed it - Transient Voltage Suppressor. It should normally be
    open-circuit, I believe.

    Try googling for "SMD codebook" for help identifying the markings on
    it. Yes, I could give you a URL, but I'm teaching you to fish, as per
    request :)
  3. Don Bruder

    Don Bruder Guest

    ST Microelectronics (SGS-Thomson).[/QUOTE]

    Time for a heartfelt "D'OH!!!!"... I knew I recognized the logo. Just
    couldn't dredge the name that went with it out of the rubble-filled
    crater that is my memory!
    Wow... MASSIVELY lucky guess! Also the only thing I could come up with
    that made even a little bit of sense.
    Smart-aleck! :)

    Thanks a bunch. I'll check the st page and try to find this little
    widget. Maybe it's supposed to be "open", maybe not... Need to find out
    for sure before I continue chasing traces. It MIGHT be the
    "deal-breaker" part that I need to fix. Or, there might still be more
    trouble further "upstream"... That's the joy of lightning hits... You
    never know WHAT might have cooked off.
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