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  1. #1

    1/4 phono plug component

    My son's electric guitar amplifier has a mono, 1/4" phono plug for the input, and that receptacle is soldered to a circuit board. The jack is broken, and missing the metal sleeve insert, so I think I need to replace the jack.

    I found a replacement part at Radio Shack and it has 2 tabs as I would have expected.
    (signal and common)
    http://www.radioshack.com/product/in...ductId=2103415

    I haven't removed the existing receptacle from the board yet, but it seems to have four contact points with the pcb.

    Why four?
    Any insights?

    Other suggestions?

    Thanks,
    Nate

    Broken input jack:
    input..jpg

    Good headphones jack:
    (even more contact points on the pcb!)
    headphone..jpg

    Input jack soldered to pcb:
    phonoPlugBoard..jpg

    Input jack from the topside:
    phonoPlugTop..jpg

    Replacement jack from Radio Shack:
    phonoPlug..jpg
    Last edited by n8Leon; 28th Feb 2010 at 07:24. Reason: Added link/pic for Radio Shack component

  2. #2
    Senior Member SC358's Avatar
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    Hi Nate,
    The extra tabs are just to secure the housing of the connector. At least one of the four tabs should be connected to ground while the fourth is the hot or circuit signal. Just desolder them all to remove the connector. Hopefully your new connector's circuit tabs fit properly to the board.
    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

  3. #3
    That's a durn loverly shot of the PC board. Usually, when there are more than 2 connectors on a mono jack, there's a switch that is either used as a feedthru or a shorting circuit (to prevent noise) when no plug is inserted. That's what I would have guessed, but the PC board shot shows that in this case, the multiple tabs are used for physical sturdiness as previous post said. The line-shaped PC trace in the middle is signal and the surrounding metal is ground.

    Your new jack won't mount to the board, so you're going to have to put little jumpers in. Hope you're ok with that. You may get some hum you didn't get before, because the old jack was insulated from the front panel and the new jack won't be. You may get a ground loop. If so, check back here. There's a way of reaming out the hole and using insulating washers. One nice thing - the new jack is going to be harder to break than the old one cuz of the metal shank.

    The headphone jack probably has more tabs because it's likely a stereo jack, wired in mono, so a stereo headphone can be used with it.

  4. #4
    It turns out the replacement part does exist!
    e.g.
    http://www.mojotone.com/amp-parts/Ja...-PC-Mount-Jack
    http://angela.com/fenderstandardampl...noampjack.aspx
    http://www.tubesandmore.com/scripts/...XP?item=S-H506

    I ordered one from Mojotone so hopefully it will be a drop-in replacement.

    Thanks for the replies!
    n8

  5. #5
    Senior Member SC358's Avatar
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    Well, that's great news - certainly a no-brainer at this point. Happy soldering!
    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

  6. #6
    Mojo shipped the jack out Tues, and it arrived today.
    My son helped me solder it up this evening,
    and we were playing guitar before the night was out.
    soldered..jpg

    Yes, I did clean the excess flux off the board after taking this picture. :-)

    Thanks again for the info!
    n8

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