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Diode identification?

Discussion in 'Electronic Components' started by DaveC, May 10, 2006.

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  1. DaveC

    DaveC Guest

    From Japanese SMPS, looks like regular 1A rectifier diode. Labeled B320219
    (the "02" is larger type than the others).

    Can't find cross-reference. Any help would be greatly appreciated.

  2. Any chance of reverse-engineering the bit of the circuit it is used in,
    and producing a bit of a circuit diagram?
  3. Pooh Bear

    Pooh Bear Guest

    It's probably not too tricky to acertain it's likely rating and speed by
    judicious examination of where it lies in the gubbins.

  4. DaveC

    DaveC Guest

    Thus spake Palindr☻me:
    Not very good at this... just a component-test monkey (c:

    But it (and its partner) seems to be across a c.t. winding of the SMPS
    transformer. Electrolytic filter caps "downstream" from these are rated at

    There are a dozen more of this type of diode in this SMPS, across other
    trans. windings.

    This is a multiple-voltage ps inside a 240v ac motor controller in a Japanese
    printing press.

  5. Arfa Daily

    Arfa Daily Guest

    If it's on the secondary side, it will not be a 'normal' 1A diode. It will
    be a high speed Schottky type. If you try to use a standard silicon
    rectifier diode, it will run very hot and fail, in short order.

  6. ian field

    ian field Guest

    If testing it shows slight reverse leakage - it could be a Shottky-barrier
    type, Most DMMs have a diode forward voltage test if the Vf is less than
    about 0.4V and more than 0.1V it almost certainly is SB, if its glass
    encapsulated - consider the possibility it's a zener, these show Vf about
    0.7V, regular diodes show about 0.6V and fast silicon types usually
    somewhere around 0.55V.

    But if any of these tests pass - it's probably OK anyway!
  7. DaveC

    DaveC Guest

    Thus spake ian field:
    The other diode ("good" one) in the circuit measures 0.4v in DMM diode test
    (Fluke meter). Not glass, epoxy (black stuff).
    Infinite both directions, according to diode test on the DMM.

    Is SB type used as rectifier in SMPS? Or is vanilla Schottky used in this

  8. ian field

    ian field Guest

    Is "the other one" with 0.4Vf identical to the one you've taken out?
  9. DaveC

    DaveC Guest

    Thus spake ian field:
    Yes, same markings. They're apparently a backward-connected set of rectifiers
    across a SMPS ct transformer secondary.

  10. Pooh Bear

    Pooh Bear Guest

    You mean the anode ( or cathode ) of the diode is directly connected to a
    reservoir cap ? It'll be a rectifier on the secondary side. It needs to be a high
    speed type and from your mention of 25V, I'd probably use a 200V part ( for
    safety's sake ). Current rating - you say it looks like 1A - would suggest a
    UF4003 replacement. Are you sure about the current rating though ?

  11. Pooh Bear

    Pooh Bear Guest

    Not necessarily Shottky actually. ( btw - is it *meant* to have a 'c' in it or
    not ? )
    Oh I don't know. A subcontractor once fitted a 1N4004 where I'd specified a
    UF4004 on a lightly loaded secondary. It ran for many hours before failing !

    They did it second time round too ! I reckon that purchasing looked at the part
    number and reckoned they could substitute. Lovely stuff working with Asians.

    Funny thing was, my colleagues looked glum since it was our first smps design. I
    ( in my infinite wisdom ! ) smelt a rat and went to it almost straight off. It
    was shorted. Just made the thing go into hiccup mode.

  12. DaveC

    DaveC Guest

  13. Pooh Bear

    Pooh Bear Guest

    SB = Shottky barrier. Techy speak for 'shottky'.

  14. Pooh Bear

    Pooh Bear Guest

    Yabbut.... It gave a list of UF400x devices which I didn't find anywhere else
    quickly. You can get the data easily with a bit of common sense. Oh sod it..... get the pdf
    I ask for a reason. Do you know the current draw on the supply ? It pays to fit
    a beefier device if unsure.

  15. The thickness of the wires coming out is often a better indication than
    the size of the body.

    IIUC, you aren't going into production with this thing, just trying to
    get it working. So you can afford to err on the side of safety and put
    in a well over-spec'ed schottky, even though a much lower spec'ed (i.e.
    lot cheaper) device would be fine too.

    Any idea why it failed?
  16. DaveC

    DaveC Guest

    Thus spake Palindr☻me:
    Nope. There are 4 identical controllers. They've all been purring along for
    near 10 years without a hiccup.
    Please, no "Go Google this" replies. I wouldn't
    ask a question here if I hadn't done that already.


    This is an invalid return address
    Please reply in the news group
  17. DaveC

    DaveC Guest

    Thus spake Pooh Bear:
    Not to get too bogged down in terminology, but
    sb = schottky barrier = schottky ?

  18. DaveC

    DaveC Guest

    Thus spake Pooh Bear:
    Like this?:

    I need it today and nte is the only maker available locally over-the-counter.

  19. Pooh Bear

    Pooh Bear Guest

    Stuff gives up after a while sometimes !

  20. Pooh Bear

    Pooh Bear Guest

    Yes. The barrier bit is optional if you like. It's about the junction inside the
    device. Like pn junctions. Except this one is a barrier. If one cares to be
    verbose, ordinary silicon diodes could be called junction diodes.

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