Home › Forums › Help/Technical Questions › Big Muff Problem (NYC)

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  • February 5, 2009 at 2:23 am #77687
    CarlosNCambria
    Participant

    Hey all
    I have this problem where the sustain knob doesn’t seem to work, it was working fine last time I used it. What happens is this, if fiddle with the volume and/or tone knob I can notice a LOT of difference between the settings, but if I turn the Sustain knob I can’t hear any difference at all, well…actually I can from about 7 – 8 (clock position) the volume drops a little, then from 8 to 3 I have about the same volume, but no change in tone or anything at all, no more gain, no anything, then from 3 – 4 the volume drops again just like with 7 – 8.
    I opened the back and noticed that the black cable (ground?) was disconnected (broken) from the battery adapter…but I don’t think that’s the problem, I don’t think it has anything to do…does it?
    I have never used a battery with it, just a universal adapter for over a year now and I always noticed a difference while playing and fiddling with all of the knobs, except for today…any ideas on what this could be?
    Shipping it back for repairs is kinda out of the question since I live in Mexico and it would probably be cheaper to just buy a new one…hopefully there is something I can do, any and all ideas are welcome.

    Thanks in Advance.

    February 5, 2009 at 4:16 am #92691
    CarlosNCambria
    Participant

    gutshot added in case someone finds it useful
    photo56ti2.jpg

    February 5, 2009 at 4:37 am #92693
    julian
    Moderator

    Sounds like a broken pot to me

    February 5, 2009 at 4:52 am #92696
    CarlosNCambria
    Participant

    that’s what I thought, do you know what kind of pot it uses?

    February 5, 2009 at 4:58 am #92697
    julian
    Moderator

    not sure, but Ned can probably help you out

    February 5, 2009 at 9:30 am #92709
    Ned Flanders
    Moderator

    100k linear,
    use this one:http://www.smallbearelec.com/Detail.bok?no=688 choose 100k from the drop down menu.

    Although I really doubt its a pot, it could be but its unlikey a new pot just stops working, try it and you’l know for sure.

    February 5, 2009 at 8:45 pm #92729
    CarlosNCambria
    Participant

    I tested the pot with a multimeter today,the resistance did vary, i also did a re-solder of the loose cable….and i get the same results :(

    EDIT:sorry i edited your post, I was meant to quote it.

    February 5, 2009 at 8:49 pm #92730
    julian
    Moderator

    I’d say contact info@ehx.com to see about getting it repaired.

    Or better yet send it to Ronsound or Analogman to get it modded and repaired.

    February 5, 2009 at 9:23 pm #92731
    Ned Flanders
    Moderator
    Quote:
    I tested the pot with a multimeter today,the resistance did vary, i also did a re-solder of the loose cable….and i get the same results :(

    EDIT:sorry i edited your post, I was meant to quote it.

    Did the resistance vary when you didn’t turn it? because if it jumps all over the place its definitely got a problem.

    February 5, 2009 at 9:45 pm #92733
    CarlosNCambria
    Participant

    I’ll look into that, thanks.

    February 5, 2009 at 9:46 pm #92734
    CarlosNCambria
    Participant
    Quote:
    Quote:
    I tested the pot with a multimeter today,the resistance did vary, i also did a re-solder of the loose cable….and i get the same results :(

    EDIT:sorry i edited your post, I was meant to quote it.

    Did the resistance vary when you didn’t turn it? because if it jumps all over the place its definitely got a problem.

    Nope, it only varied when I turned it.

    February 5, 2009 at 10:56 pm #92737
    Ned Flanders
    Moderator

    Well that normal thats what pots are, variable resistors.
    I’d say the pot is fine, i would start looking elsewhere for a problem.
    Post Hi resolution pics of the component side and then the PCB side. By hi res I mean BIG ones, and clear too.

    February 5, 2009 at 11:10 pm #92739
    CarlosNCambria
    Participant

    I will test connectivity between the components on the first phase of the pot just to see if everything is ok, and I’ll look for a camera to get the pic (that would mean later tonight or tomorrow morning), thanks for your time! really!
    (I noticed you post on the HC as well, and that you DO love the Muff ;) that’s really cool)

    February 5, 2009 at 11:27 pm #92742
    Ned Flanders
    Moderator

    Yea, I jump all over big muff threads.LOL

    February 12, 2009 at 1:14 am #93133
    CarlosNCambria
    Participant

    Hello Ned, I finally managed to get a camera to get some decent pics, here are the links since they are BIG
    //http://img22.imageshack.us/img22/6084/001ag3.jpg
    //http://img516.imageshack.us/img516/9823/002di6.jpg
    //http://img19.imageshack.us/img19/6786/003ew8.jpg

    I also tested out some things:
    I soldered the ground cable. (nothing changed)
    I unsoldered (sp?) the pot and tested it with an oscilloscope and a signal generator…it works (I used another pot to see how it affected the signal, the one of the muff did the same thing)
    I tested connectivity on components and cables and it worked (the only thing I might doubt is working is the push button/switch thing, I’m not sure it’s connected correctly but I would say it is, no reason why it wouldnt be)
    Tested the transistors to see there had no connectivity between the legs (none), they are all working, even managed to read the 0.7V of saturation.

    And then… I stopped, I have no idea what might be wrong, I hope the pictures help :)

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