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Logitech G51 Speaker System Repair

Discussion in 'Troubleshooting and Repair' started by Teal, Jan 9, 2013.

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  1. Teal

    Teal

    3
    0
    Jan 9, 2013
    I have a set of G51 5.1 surround speakers hooked up to my PC that are well past their warranty and suddenly stopped working.

    The speakers are set up like this: 4 audio leads are connected from the sound card on the back of my PC to the subwoofer (centre, rear, sub etc..). A control box (which sits on my desk) is also connected to the subwoofer via some sort of serial port. The control box has headphone and microphone inputs on it. Each of the 5 speakers connect via a single cable into the sub as well.

    Now, when I have my headphones plugged in to the control box, the speakers are automatically muted (I do this at night so I don't disturb my neighbors). When I unplug the headphones everything reverts. There's even separate volume levels the control box stores for headphones and speakers.

    Now, when I unplugged my headphones today my speakers put out no sound, not even a hum. The indicators on the control box indicate the headphones are unplugged, so there isn't anything stuck in the jack. The headphones in the meantime, still work fine when plugged in, which means to me that the output from the sound card is A-okay. All the levels on my PC read normal as well. Tapping on any of the leads yields nothing.

    Now, obviously, 5 speakers don't fry at the same time usually, so I'm thinking it's a blown fuse, and I'm ready to tear apart the subwoofer to find it, but I'm posting here first for further consultation in case I missed something obvious.

    Anyone have a similar experience?
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
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    Jan 21, 2010
    Failure of all 4 channels would be indicative of a common fault. The fact that the device seems powered up (you say it indicates the headphones are not plugged in) would mean that the entire power supply has not failed (and I would expect a fuse in the primary and its failure would stop everything).

    Is it mains powered, or does it have an external power supply that plugs into it?
     
  3. Teal

    Teal

    3
    0
    Jan 9, 2013
    The power supply is internal since it plugs straight into the wall (and into the sub), and everything with it seems fine. Of course there could be a fault that's preventing power getting to the speakers, but since there's no indicators on the speakers I can't tell.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Do the speakers have their own amplifiers in them?

    If not, can you test them with something else?
     
  5. Teal

    Teal

    3
    0
    Jan 9, 2013
    Tested each of the speakers this morning by plugging them into something else. They are working it seems.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    OK, I think that opening *something* may be in order.

    If you can, the control box might be a good start. It is possible that the switching on the headphone jack uses a different method to turn on the light, and to switch the audio.

    It's a long shot, but best to eliminate the possibility of some sort of mechanical failure or contact resistance problem.
     
  7. quantumtangles

    quantumtangles

    152
    3
    Dec 19, 2012
    Speaker Plug Issue?

    When you push the headphone jack into the headphone socket, this mutes the speakers.

    Why? Because it is a continuously 'on' switch...at least until you push a headphone jack in, at which point the speakers are disconnected...(off) and only the headphones are connected to the audio source.

    You use the headphones regularly, so metal fatigue inside the headphone socket is a real possibility. The switch still works for headphones, but it no longer springs back into place when you remove the headphones, preventing the circuit to the speakers being completed.

    Thats why, when you pulled the headphones out, the speakers did not work...but the headphones still work if you put them back into the socket. Which is to say, the audio signal is still there, but the speakers are no longer connected to it.

    For these reasons, I think the culprit is the headphone socket. It works like any other switch...disconnecting the main speakers whenever the headphone jack is plugged in. But now, because of metal fatigue, or lack of springiness, no reconnect happens when you pull out the headphone jack.

    If this is correct, it should be an inexpensive repair. Open the case where the headphone socket is at...have a look at it...see how it connects...repair or replace the headphone jack socket.

    Likely there will be 4 screws at the back of the little handheld unit (is the headphone socket input inside a sort of rectangular handheld box linked via an extension cord....at the end of which (inside the box), a volume control, bass boost, line in and headphone socket?). Pop the screws off and have a look. Lets face it, taking things apart can be a lot more fun than using them (my precise line of thinking moments before I took my iphone apart). Sigh.
     
    Last edited: Jan 11, 2013
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
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    Jan 21, 2010
    Remember that Teal reports that there is some sort of indication that the headphones are present, and that it works.

    Whilst the problem could be as simple as you suggest, but I fear there is more to it.

    Agreed though, excellent if it is something this simple.
     
  9. quantumtangles

    quantumtangles

    152
    3
    Dec 19, 2012
    Yes I agree it could be something else Steve.

    The failure rate of this type of control unit (where the headphones etc are attached) is high after 3-4 years of continuous use. If it is not the headphone socket, I would put my money on it being the cable leaving the control unit.

    Fatigue in the wire (connecting control unit to main unit) varies with user behaviour. Fine if the control unit is stationary, (e.g. on a desk and not moved around)...but people who routinely move the control unit about cause wire fatigue over time. Most of the torque or rotational force applied when moving the control unit is soaked up by the cable just as it exits the control unit.

    So the fault could well be where the cable exits the control unit, possibly shorting the audio signal to the speakers but not to the headphones. Slightly more complicated...higher chance of not repairing it perfectly first time...but well worth looking at as these units are worth repairing :D
     
    Last edited: Jan 13, 2013
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