Home › Forums › Help/Technical Questions › Big Muff Pi – No Sound With Effect but Sound Audible when Bypassed

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  • May 9, 2019 at 11:15 am #85746
    nickhellyeah
    Member

    Hi

    I have an old well loved/used Big Muff Pi.

    The issue is that the pedal doesn’t emit any sound when the effect is activated but does allow the input signal to be heard when the effect is bypassed.

    I have tried swapping over to brand new 9v batteries and yet it still doesn’t produce any sound when effect is activated.

    I understand that a band mate who borrowed it a while ago claims he used a ‘ehx compatible’ PSU.

    I’m not sure if the problems happened while he had it but it’s not working properly now with a battery or with my Diago PS04 jack attached to my PSU (a combination that works fine with my Small Stone phaser).

    Sorry for the ignorance, but would using a PSU of the wrong polarity cause the pedal to simply not work or would this be detrimental and cause circuitry to fail?

    I’m no electronics expert so haven’t inspected the inner workings of the pedal yet but would value the community’s experience and knowledge to help me sort this.

    Many Thanks,

    Nick

    May 9, 2019 at 11:21 am #125191
    The EH Man
    Moderator

    It’s entirely possible that the power supply damaged the circuit. I would hand it off to an experienced tech for repair.

    May 9, 2019 at 11:59 am #125193
    EHX STAFF
    Keymaster

    Yes it could have taken a hit from a bad supply or the switch is bad. They get corroded and dirty over time and need to be cleaned or replaced.
    Please contact service. They can help you out.
    info@ehx.com

    May 9, 2019 at 12:30 pm #125195
    nickhellyeah
    Member

    Thanks for the replies.

    I’ll contact my local tech shop and see what they think.

    Hopefully the outcome won’t be too expensive or even terminal!

    Nick

    May 22, 2019 at 9:40 am #125251
    nickhellyeah
    Member

    Hi

    I haven’t taken it to my shop yet as they were quoting what seemed to be high prices for the inspection let alone the repair – £50 just to look at it. :-(

    To help me deduce whether I have a should opt for the repair can you please confirm from the photos in my Google Drive (below) whether it is a vintage original pedal?

    https://drive.google.com/folderview?id=1eGDMxWWpqmRWKrV0rmYa2zjJi4mo9hxP

    Looking at forum posts it seems people refer to numbers on the pots but I cannot see anything but an S symbol on the underside of each pot.

    Many Thanks,

    Nick

    May 22, 2019 at 4:48 pm #125253
    EHX STAFF
    Keymaster

    Did you write ehx service dept???
    info@ehx.com

    May 22, 2019 at 5:14 pm #125254
    nickhellyeah
    Member

    Hi

    I haven’t contacted ehx direct only posted messaged on this forum.

    I assume that the service department is in the US and therefore delivery costs would be prohibitive.

    Am I correct?

    Thanks,

    Nick

    May 22, 2019 at 8:43 pm #125255
    EHX STAFF
    Keymaster

    We have a service center in the UK

    May 22, 2019 at 8:45 pm #125256
    EHX STAFF
    Keymaster

    John Williams / Electro-Harmonix
    13 Cwmdonkin Terrace
    Swansea SA2 0RQ
    United Kingdom
    Tel : +44 179 247 3258
    Cell: +44 752 888 6326
    Email: electroharmonixuk@virginmedia.com

    May 23, 2019 at 8:07 am #125257
    nickhellyeah
    Member

    Great stuff.

    I’ve sent an email off to John.

    Many thanks to all that have helped!

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