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How do I replace a compact disc player transformer??

Discussion in 'Electronic Basics' started by [email protected], Mar 11, 2005.

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  1. Guest

    I have a CD player that stopped turning on. Inside the cabinet I found
    that the transformer looked corroded/generally suspicious so I
    industriously ordered a replacement (read: I don't know what I'm
    doing). I unscrewed the brackets of the existent xformer and
    discovered that it is attached to the circuit card below it. Turning
    the whole thing to the side, I can see that the posts from the
    transformer are inserted into the card, and at each point of insertion
    there is a rounded metal nub (melted solder?) on the other side (the
    side the posts would exit were they to poke through).

    Here's my problem: I cannot remove the bad transformer from the card.
    It seems to be held in by the posts that are stuck into the card (are
    they soldered in?). How do I remove the old xformer and install the
    new one???

    I realize that I should probably take it to a professional; aside from
    that, can anyone talk me through this?


  2. mike

    mike Guest

    Repair rule number one: If it ain't broke, don't fix it.

    Before you risk breaking the circuit board, verify that the transformer
    is bad. All it takes is an AC voltmeter to determine if it's putting
    out volts. If you don't have or don't know how to use a voltmeter,
    STOP immediately and befriend someone who does. You'll learn more in
    10 minutes with an expert than you will trying to sort thru all the
    inputs you get on the web.

    FWIW, the transformer wouldn't be the first or second or third or fourth
    place I'd look for a bad part.

    Return address is VALID but some sites block emails
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  3. Jamie

    Jamie Guest

    Blow torch ? :)
  4. Art

    Art Guest

    Unless you are adept at repair techniques and have the appropriate tools you
    will need to have it done for you. The Blow Torch Technique will remove the
    part, and overheat the circuit board in areas that you will not prefer.
  5. Jamie

    Jamie Guest

    LOL!, some people are gullible! :)
  6. Forget the blowtorch, except for grins.

    Assuming you do replace the transformer:
    Get a soldering iron and a solder removal
    means, such as a mechanical sucker or
    wicking copper braid. Melt each joint
    and try to clear the space between the
    side of the hole and the transformer pin.
    Finally, wiggle each pin with some pliars
    to break the (hopefully) slight remaining
    bond between pin and hole. After doing
    the last pin and then removing mechanical
    fasteners, lift the transformer out. Solder
    the new one in with the same orientation
    as the old one. (You can find soldering
    tips on the web.)
    I second Mike's advice about getting a friend to
    help. But taking it to a pro will probably cost
    more than the equipment is worth. As Mike
    suggested, an AC Voltmeter will tell you whether
    the transformer is working. Here are a few tips
    on how to do that with a multimeter:

    Unplug the player, open the case, and get the
    circuit board exposed enough to permit you to
    safely probe the power supply. Be sure that it
    is on an insulating surface and that the arrangment
    of things is stable and does not create any circuit
    other than what was there with the case closed.

    With the player unplugged, use the Ohms setting
    to discover which terminals of the transformer
    connect to the line, hot or neutral. Be careful
    to avoid touching those during the next steps,
    with either yourself or your probes. It would
    be prudent to mark them with masking tape
    or something unless you have good memory.

    Put on a pair of clean rubber-soled shoes and
    get a completely wooden or plastic chair to sit
    on for the next few steps. Or, if you are steady
    on your feet, prepare to stand in those shoes.

    Plug in the player and set the power switch to
    the on position.

    Grasp the probe tips carefully on the insulated
    part, well back from the metallic tips.

    Use the AC Volts measurement setting on your
    multimeter to measure most or all pair-wise
    combinations of the remaining transformer
    terminals, the ones not marked or noted in
    the unpowered step above.

    Unplug the player.

    If you saw at least 5 VAC on any of those
    combinations, then it is very unlikely that you
    have a transformer that needs replacing.

    If you saw little or no AC, then be sure there
    is no blown fuse in the line side of the supply.
    If there was a blown fuse, replace it. Otherwise,
    replacing the transformer is indicated.
    You're welcome.
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