1. Forum
  2. Usenet
  3. SCI.ELECTRONICS.REPAIR

  • Re: Altec Lansing ATP3 Speaker system transformer failed.

    From Jeff Liebermann@21:1/5 to Bob F on Sun Apr 28 19:57:51 2024
    On Sun, 28 Apr 2024 16:08:57 -0700, Bob F <bobnospam@gmail.com> wrote:

    This speaker system I used on my main computer died yesterday - no power
    at all.

    I traced the problem to the transformer, a 12.5V 2.5 A TP57U25F from Ten
    Pad Industrial.

    Check your typing. The company is Ten Pao. <https://www.google.com/search?q=ten+pao+transformer>
    There is usually a part number on their transformers. Find the number
    and

    Testing the transformer coils, neither the 117V input or
    the 12.5 V secondary show conductivity - they are both open circuit. The
    fuse for the primary circuit was not blown.

    Conductivity? Plug it in and measure the AC voltage produced at the
    output of the transformer.

    My question here is, if both coils are open circuit, does this suggest
    that a major short on the PC board got the transformer too hot so it
    tripped temp circuit cutoffs in both coils, so it is unlikely that
    replacing or fixing the transformer will fix the speaker? Or, is this
    kind of failure common for such transformers?

    I've seen opens on commodity power transformers are when there is
    mechanical or chemical damage to the wires. More common are the
    thermal fuses hidden under the tape covering the transformer windings.

    If I wanted to try a different transformer to test the board, what
    should I want the transformers open circuit voltage to read on my
    Greenlee DM-20 DVM. Should that be 12.5V? I do have a variable voltage >variac I could use to adjust a slightly higher voltage transformer down
    to 12.5 or whatever should be needed.

    I can't answer that without knowning something about the type of power
    supply. Is the bridge full wave, full wave center tapped, or
    something else? Is the 12.5 V before or after the voltage regulator?
    Digging with Google: <https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-audio-equipment/58859-system-dead-atp3-altec-lansing-computer-speak-system-with-subwoofer>
    Looks like you're not the only one with a transformer problem in the
    ATP3. At least we now have the part number, but for the 230 VAC
    version:
    TEN PAO Model no.:TG51219F0
    Input: AC 230V/50Hz
    Output: AC 12.5V/2.5A
    I can't figure out the 117VAC version part number.





    "Hacking an Altec-Lansing ATP3 Subwoofer for Stand-Alone Operation" <http://www.kk4ice.com/?p=570>
    This doesn't answer your question, but might be useful reading. Please
    note the external on-off switch wiring. One a different model speaker
    system, I had a similar "no power" failure that was caused by me
    kicking the sub-woofer enclosure and eventually breaking the on-off
    switch.



    --
    Jeff Liebermann jeffl@cruzio.com
    PO Box 272 http://www.LearnByDestroying.com
    Ben Lomond CA 95005-0272
    Skype: JeffLiebermann AE6KS 831-336-2558

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to Bob F on Mon Apr 29 09:28:59 2024
    Bob F <bobnospam@gmail.com> wrote:

    [...]
    No output. Ohmmeter resistance shows infinite on primary and secondary.
    2 leads on primary, 2 on secondary, going to 4 diodes on the circuit board.

    Does it look badly burnt or is there no physical sign of stress?

    It would be very unlikely that both windings would go O/C simultaneously
    unless it had failed catastrophically and that would be rather obvious
    from the outside.

    Simple question: Did you measure the resistance between the two ends of
    the same winding or are the terminals laid out in a confusing way, so
    you measured resistance between two different windings?


    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)