Home Forums GuitarPCB Build Support Muffn Low Output (solved)

Viewing 7 posts - 1 through 7 (of 7 total)
  • Author
    Posts
  • #11982
    Marc
    Participant

    Hi Everyone,

    I just wired up my first pedal, a Muffn Civil War.  The pedal works, as in I have bypass and there is output when the pedal circuit is turned on.  However it sounds closer to a fuzz and barely driven tube driver then any muff i’ve heard or played.  That and the clipping switch isn’t working, no change in output regardless what position the switch is in. I did verify all the resistors and capacitor values before beginning the install.  FWIW I tested it using a 90’s MIM strat and 90’s MIA strat with EMG DG20’s fed into a Deluxe Reverb and an Ampeg VL1002.

    Battery Voltage: 9.45v
    BC549C Pulled Out the readings are(E/B/C):
    Q1: 0.00v/1.625v/9.27v
    Q2: 0.00v/1.607v/9.27v
    Q3: 0.00v/1.504v/8.53v
    Q4: 0.00v/1.631v/9.44v

    BC549C Installed the readings are(E/B/C):
    Q1: 57.6mv/0.609v/7.58v
    Q2: 59.3mv/0.601v/7.52v
    Q3: 47.1mv/0.595v/7.26v
    Q4: 0.404v/0.905v/7.94v

    The value of Q3 with the transistor removed looks incorrect, am I right in my assumption?  The same with Q4 with the transistor installed? I did re-flow all of the solder connections, you may notice the pulled pad at the ground connection, I had a wire snap from debugging. I had my led installed on the main board at first, it has been moved to the switch board and is working.  Photos are below. Please let me know if you need any additional information or photos. Thank you very much for any assistance or insight you all might be able to provide.

    Regards,
    Marc

    #11984
    wilkie1
    Moderator

    Your photos show the BC549C transistors inserted as shown on the board.  The Build Notes tell you that these have a different pin out and should be reversed on the board.

    #11989
    Marc
    Participant

    🤦
    Well apparently I can not read data sheets for the life of me because it is functioning perfectly. Fairchild ON Data Sheet
    Thanks for pointing out my error, so glad I put sockets on the board.

    -Marc

    #11997
    wilkie1
    Moderator

    Happy to hear that it works fine now.

    So, what will your next project be?  We’ll be here to help!

    #12056
    Marc
    Participant

    Next project is to build a second one, more mods and I think I’m comfortable with experimenting with different component values.  Not that I’m not happy with the sound of this build, its great, gritty but clear and just dark enough.  Then maybe a modulation or compressor, not sure just yet.

    One last question, when I turn the sustain/distortion knob all the way down the pedal output drops to zero.  Is this normal or a bad pot 100k linear pot?

    Cheers,
    Marc

    #12066
    wilkie1
    Moderator

    Some pots will actually short to the metal frame of the device when turned past the end of the carbon trace on the wiper disc.  That is probably normal for many pots particularly inexpensive ones that we tend to use for most pedals.

    In normal use, you will not likely want to do this.

    #12096
    Barry
    Keymaster

    This proper troubleshoot post is much appreciated as it allows us to actually solve your problem quickly.

    As opposed to the more common:  “I built it correctly but it doesn’t work, anyone know why?”

    End result is Posted on March 29th and Solved on March 29th.

    Thanks for taking the time and enjoy your build.

Viewing 7 posts - 1 through 7 (of 7 total)
  • You must be logged in to reply to this topic.