Need help tracking down a transformer

Discussion in 'General Electronics Chat' started by Zetrox2k, Apr 8, 2010.

  1. Zetrox2k

    Thread Starter New Member

    Apr 8, 2010
    7
    0
    Hey guys. My beloved Dreamcast console has recenly suffered from a transformer failure on the PSU circuit, and seeing as I've just recently picked up a new hobby, electronics, I've decided to fix it. I've de-soldered it from the circuit but Im unsure what type of transformer I need to replace it with.

    The info I've been able to pull of it are as follows:

    On top, 3 separate codes:

    SY33BJ2

    BE128A

    903GA

    On the bottom, one code:

    FED33110B3H-BD-09

    the base has 9 pins on one side 5 on the other.

    Style of transformer is similar to the one pictured on:

    http://www.allproducts.com/manufacture100/zn907/product1.jpg

    an actual picture of the console with the psu and transformer (upper left) can be found here:

    http://upload.wikimedia.org/wikipedia/en/1/11/Dreamcast-internal.jpg

    Please excuse the n00b explanations! Thanks Guys!
     
  2. Externet

    AAC Fanatic!

    Nov 29, 2005
    758
    57
    Hi.
    From hundreds of switching power supplies failures I have dealth with, only once I found the transformer bad; and had visible melt/burn signs. Not to say yours is good, but chances are poor.
    Measure the DC voltage at the largest electrolytic capacitor, should be 170V for 120VAC mains.
    If there, check the health of the transistor or mosfet nearby held on the aluminium, and come back with findings. There is much more steps to check later.
    These power supplies protect themselves by shutting down if a short develops somewhere else.

    Measure voltages at its output nylon connector disconnected -near left bottom corner- when turned on.
     
    Last edited: Apr 8, 2010
  3. Zetrox2k

    Thread Starter New Member

    Apr 8, 2010
    7
    0
    Thanks for the quick reply mate!

    Just as in your situation there are also visible melt/burn signs on the transformer which is what led me to that conclusion.

    Oh and to add, before the console failed there was a very strong electrical burn smell. No smoke though. Im guessing the capacitors would have released some smoke if they burnt out?

    Will a continuity check suffice to check the health status of the rest of the components, or do i need to go more in depth and check voltages, resistance, etc?
     
    Last edited: Apr 8, 2010
  4. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    If your transformer failed, you can usually bet your bottom dollar that there is another problem. The CAPS would be the next to test. Do you have a capacitance tester?
     
  5. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,750
    759
    Supply doesn't show any sign of major damage.
    Check the diodes on the secondary.
    Most of the time a shorted diode is the culprit in those kind of PSU's
     
  6. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    Good point. :)

    Does it ever occurs to you the photo is a wiki photo and not the actual failed power supply that the OP has?
     
  7. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,750
    759
    wiki or not....OP should show his photo.
    then only we can really comment
     
  8. Zetrox2k

    Thread Starter New Member

    Apr 8, 2010
    7
    0
    Thanks for al the replies guys, ill post some photos tomorrow of my failed PSU. There is no other, not even slight bit of visible damage to the rest of the board, aside from the melt/burn marks on the transformer. The rest of the board seems intact. I've just had a second system fail that my wife bought me for my birthday, and have pin pointed the problem to a faulty third party video lead. both units failed within five minutes.

    sorry bud, no capacitance tester, i migh be able to get a hold of one though....
     
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