Internittent Fault On Input Jack Of Mg50dfx

Discussion in 'The Workbench' started by John Meighan, Oct 2, 2017.

  1. John Meighan

    John Meighan New Member

    Oct 2, 2017
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    Hi All
    New to the forum just got this amp second hand it seems OK but the input is unreliable can anyone offer any ideas on how to fis it. It seems the input jack is soldered direct to the pcb.
    Thanks in advance
  2. ampmadscientist

    ampmadscientist Well-Known Member

    Jun 26, 2014
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    On the wrong side of the tracks.
    The jack can be broken when somebody trips over the guitar lead.
    But soldering can damage the circuit board if you don't have professional equipment.

    Take off the knobs, unscrew all the nuts, unplug all the connectors from the board (mark the connectors so they go back in the right place).
    Then unscrew the mounting posts....and lift the board out.

    But maybe you should have an experienced person do this...because it can turn the amp into a paper weight if you make a mistake.

    The new jack is made by CLIFF UK.
    But make sure the jack says: "UK."
    Because there is a lot of fake CLIFF jacks being sold from China, and these knock off jacks are JUNK.
    (the China jack works for about 2 weeks then fails)

    Make sure you buy UK parts.
  3. myersbw

    myersbw Active Member

    Oct 22, 2015
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    SW Ohio
  4. Matt_Krush

    Matt_Krush Well-Known Member

    Dec 14, 2015
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    Saginaw MI
    What I do, is spin the jack upside down and solder jumper leads from the jack pins to the board.
    So if it fails again, I am not re-soldering to an already flimsy board, and I don't have to worry about of someone steps on the cord, the force cracking the board.
  5. BowerR64

    BowerR64 Well-Known Member

    Nov 23, 2014
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    expect a bit of work on this repair.

    Ive had to fix a few MGs because of this same issue and the work involves removing all the knobs, the insert and line in jacks anf then all the nuts to the pots.

    Once you do that you have to remove the board and flp it over to get to the board. Ive had just the solder breal loose wich was a fairly easy repair but i had a MG250 that had all the trace lines on the board crack and then i had to solder wores from point to point and actually glue the jack to the board so that it wasnt relying on just the solder connections to hold it down.

    It seems cheesy to use plastic jacks but there is a reason for it being the metal chassis and stuff. I tried metal more heavy duty jacks in the past to try and "upgrade" the what i thought was a cheap design and then it cause grounding issues and stuff so even though you may thing a plastic input or output jack is a dumb cheap idea there is a reason for it. stick with the design

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