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What have I done to my reciever?!?!?

Discussion in 'Electronic Repair' started by Fred Mann, May 27, 2007.

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  1. Fred Mann

    Fred Mann Guest

    I have speakers all over my house, wired to two seperate receivers . One
    speaker is wired to both receivers. This has not caused a problem for years.
    I usually remember to turn one receiver off before turning the other one on.
    But occasionally, I have forgotten to do this -- also no problem. Until last
    night, that is. I powered up my second receiver while the first one was
    still on and played some music through it and burned up something in the
    first receiver. It started making a hum in the speakers and clearly smelled
    of burning electronics. So I turned it off. When I got back to receiver one,
    it too was non-responsive on both sets of speakers. It was still powered on
    but nothing will come out of the speakers now. Not even through the
    headphones. I took the top off and tested the three fuses that I could see
    with a volt meter. All worked fine.
    So ... is there anything obvious I should check, or should I just buy a new
    I hope I provided enough info.
  2. Fred Mann

    Fred Mann Guest

    P.S. - The receiver I care about is a Pioneer VSX 401 .
  3. James Sweet

    James Sweet Guest

    If the fuses are ok then you blew the outputs. Fixable if they're decent
    recievers, but probably not worth it if they're worth <$100 or so.

    Next time install some sort of switch on the output so that only one
    reciever can be connected to the speakers at a time. I'm really surprised
    you didn't blow up one or both amps sooner, even if one was turned off.
  4. Fred Mann

    Fred Mann Guest

    Thanks James!
    Just curious ... what would actually have been destroyed in this scenario? I
    believe every single speaker output was rendered non-functional - even
    outputs that weren't hooked up. Also, there was no burning smell on the
    "good" receiver.
  5. James Sweet

    James Sweet Guest

    Many amps have a protection circuit, if they detect a fault on one output,
    the rest will be disabled until the fault is corrected. There also may be a
    fuse further up the line somewhere, such as in the power supply area, but I
    wouldn't count on it.
  6. jakdedert

    jakdedert Guest

    Fred Mann wrote:
    If you look at the answer again you'll see the word 'outputs'. This
    refers to the output devices in your receiver(s). Different ones use
    different types. Some have discrete transistor devices. If one of
    those, the output transistors and possibly other components associated
    with them are now defective.

    Troubleshooting one of these is more difficult--but not as expensive to
    fix as the other type--that type being a unit with most of the amplifier
    circuitry encapsulated in an epoxy module.

    Those modules are easier to troubleshoot because for the most part, the
    devices which will fail in such a scenario are all within that one
    module. Replacing the one unit will likely fix the problem. OTOH, the
    price for the part is higher than the various discrete parts in the
    first type. Replacement is more difficult in some cases because of
    soldering the number of closely-spaced pins involved. Many of the
    modules are discontinued and difficult to find.

  7. Guest

    How silly. Next time put a couple of 4 or 8 ohm Rs onto your speaker,
    and connect one amp via one of them and the other via the other.

  8. b

    b Guest

    I hate to sound wise after the event, but that was a disaster just
    waiting to happen.

    you will need to troubleshoot the output stages of the amp. Good luck
    - many amps drive even experienced techs to tears!

    try for schematics etc. And if you fix it, then make
    the next thing you do adding a switch box of some kind into this
    harebrained speaker circuit !
  9. Jamie

    Jamie Guest

    A lot of units have a processor reset sequence you need to go through
    when it shuts down like that due to some over load..
    Like holding in a couple buttons when you power it up and so on..
    AS far as the other receiver generating smoke/smell, I'm sure that
    doesn't share the same kind of protection as I just detailed out.
  10. Fred Mann

    Fred Mann Guest

    Thanks for all the replies. I think I'm going to throw in the towel on this
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