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Logitech x-540 repair

Discussion in 'Troubleshooting and Repair' started by davidjk, Oct 2, 2014.

  1. davidjk

    davidjk

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    Oct 2, 2014
    i have a 5.1 surround system that is playing up. it will be playing at normal volume then gets really quiet, then after an unspecified time returns to normal, or can change constantly quieter then louder.
    I have managed to figure out it is something in the electronics of the amplifier rather than the volume knob or the input.
    i think this because if i turn the volume up high it still does the same and doesnt crackle ruling out the volume knob.
    if i plug it into another device it still does the same thing.

    my question is. how do i track down the faulty component?
     
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,266
    Nov 28, 2011
    Hi David and welcome to Electronics Point :)

    This is a pretty recent product and I doubt that technical information will be available anywhere. I've looked on elektrotanya, a good source of service manuals, but it's not listed there. If you can get any service information on it, that would be great.

    I guess you should start by opening up the subwoofer - I assume all the amplifiers are in the subwoofer enclosure - and taking some photos of it, so we know what we're dealing with. Start with an overview of what's inside the enclosure, then take some close-ups of the individual boards. See https://www.electronicspoint.com/resources/how-to-take-photos-of-circuit-boards.6/ for guidance, and also https://www.electronicspoint.com/resources/photos-with-phones.27/ if you're using a phone to take the photos.

    Are you using all of the speakers? When the volume varies, does the volume from all speakers vary together?

    What are you driving it from? Have you tried driving it from a different source such as a stereo radio tuner? If not, can you do that? The unit has some smart processing inside it that will vary the volume, and it could be getting confused by certain characteristics of the signal you're feeding it.
     
  3. davidjk

    davidjk

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    Oct 2, 2014
    hi, thank you for replying, the volume does indeed vary on all speakers at the same time. i have tried using it from a different source, not just pc input.
    it has worked fine for years but recently started playing up.
    i will get the pictures uploaded asap. many thanks
     
  4. forest

    forest

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    Sep 14, 2018
    My Logitech X-540 just developed the same problem. @davidjk Did you manage to solve it, or even narrow it down further?
     
  5. kellys_eye

    kellys_eye

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    Jun 25, 2010
    The OP last posted 4 years ago and hasn't been back since - I very much doubt you'll be hearing from them.
     
  6. forest

    forest

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    Sep 14, 2018
    I saw the date. It's always worth a try when you're looking for information, and even if OP doesn't respond, the next person to land here with this problem will see that there's now another person (me) who might have info to share.
     
  7. kellys_eye

    kellys_eye

    4,284
    1,145
    Jun 25, 2010
    Well the OP was asked to upload pictures and expand on the issue but failed to do so.

    If you started your own thread on the subject and did what the OP 'should' have done we might be better placed to assist you in fixing YOUR problem.....

    or we could wait for the OP to reply!
     
  8. forest

    forest

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    Sep 14, 2018
    To whomever next arrives here with the same problem, try this before mucking about with subwoofer disassembly or PCB photos:

    Pick up a can of contact cleaner spray, open the volume control housing (there are three screws hidden behind the foam feet), and spray the cleaner into the volume potentiometer while repeatedly turning it up and down for a while. Consider cleaning the other pot, too, as a preventative measure.

    After several days with no more of the erratic volume changes that were happening every few minutes, I think it's safe to say that the cleaning fixed it. (Lesson: Don't rule out dirty pots as the cause of a problem just because they don't crackle or fix themselves when you turn them.)
     
    Last edited: Sep 18, 2018
  9. forest

    forest

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    Sep 14, 2018
    In case cleaning doesn't fix it, the pot in question is a 50k ohm linear taper snap-in style. Bourns PDB12-M4201-503BF looks like a perfect replacement, and CTS Electrocomponents 296XA253B1N or 296XF253B1N look close enough. I couldn't find those available in small quantities, but the Bourns PDB12-H4251-503BF works well if you cut the shaft down a bit.
     
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