Home Forums GuitarPCB Build Support MKC3 – Sound Sometimes Cuts Out

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  • #3869
    Luckbad
    Participant

    Howdy! I’ve had this issue for a while now but finally got around to trying to figure out.

    Basically, here are the symptoms:

    • Usually, if I turn on the MKC3 with the foot switch and keep it depressed, the light will activate but no sound will come out. Letting go of the foot switch lets sound pass through.
    • Sometimes, no sound comes through and I have to stomp on it twice to get it to work.
    • If I pick the thing up and rotate it  (so the pedal goes from rightside-up to upside-down), I can generally get it to cut out, and it stays with no sound coming through until I rotate it a little bit in the other direction.

    The symptoms made me think it was something physical, so I rotated the heck out of it a bunch of times. Nothing is moving at all in there. The wires are Barry’s hookup wire so they’re nice and solidly in place.

    I tried holding down every individual component while rotating and that never prevented the cutout from occurring.

    Could it be the 3PDT board itself?

    I should probably dig out the probe thing I built according to the instructions (going to search after I submit) to see where in the world it’s actually cutting out…

    Let me know if there’s anything obvious going on. I’ll post if there’s any other useful information after probing.

    #3870
    Luckbad
    Participant

    Okay. That probe really is quite useful.

    When the signal cuts out, it’s right at BI on the 3PDT.

    The I still has a signal, but BI doesn’t have one.

    Does that mean I need to pick up another 3PDT? I might actually have a few more lying around somewhere. Maybe the first step would be replacing that one wire I burned? Could be a problem, but there isn’t any wire showing through.

    Thanks!

    #3872
    Barry
    Keymaster

    Re-flow all solder joints and replace burnt wire. It is probably as simple as that and yes the Audio Probe is a TOOL that I wish everyone would use since it narrows down the possibilities to just a few things in a matter of minutes. There could still be an issue with the Main Board but I would start with a careful re-flow.

    Excellent execution of Pot Condoms, PCB Secure mounts, DPDT Wiring board and sockets!

    #3874
    wilkie1
    Moderator

    I agree with Barry.  The signal probe quickly narrowed down to the area of concern.

    I think you soldering joints all look great including the ones on the foot switch.  Therefore, I suspect that you have a defective foot switch since it also acts weird when you step on it.  Since you loose signal precisely at the foot switch between lugs 2 and 1 and the solder joints there look fine, I think that is the problem.

    #3876
    Luckbad
    Participant

    Thanks dudes. I’ll grab a couple of spare foot switches before breaking out the soldering setup. Maybe I’ll get lucky and a reflow and wire will fix it.

    #3878
    Billy
    Moderator

    Your solder joint at the IN ‘T’ pad on the main board looks a little ball like I’d try reflowing that one in particular

     

    The first thing I noticed was your burnt wire and the exposed bare wire, it’s possible you could have damaged the 3PDT lugs internally with too much heat, to test it continuity check your 3PDT  middle common row with the top row when you get the cutting out happening that’ll at least let you know if the 3PDT is faulty

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