Any idea what this mod is?....

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BeardyAndyBeardyAndy Frets: 716
edited June 2019 in Making & Modding
Just bought Cry Baby on eBay and it's arrived with a mod, not sure of it's purpose?

Is it a broken switch??

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Comments

  • FunkfingersFunkfingers Frets: 14321
    Looks like a switch to select between capacitors of two different values.

    Yes, the shaft of the switch is missing. This might be intentional. The switch could act as a preset. Shortening the switch lever shaft avoids unintentional changes on stage.
    Be seeing you.
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  • maltingsaudiomaltingsaudio Frets: 3098
    Looks to me like the switch is DPDT so it puts the filter caps in circuit when activated as possibly hipass and Lopass filters. And yes I think the switch itself has ad it’s shaft broken
    www.maltingsaudio.co.uk
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  • BeardyAndyBeardyAndy Frets: 716
    @Funkfingers @maltingsaudio ;

    Thanks guys. I bought it with intermittent fault so fingers crossed it could be this, a new switch is already on its way!
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  • ICBMICBM Frets: 71956
    It's also wired in the worst possible way for reliability - with the signal passing through both switch poles in series - so even if it isn't broken now there's a good chance it will cause trouble at some point.

    To select two different component values, they only need to be switched at *one* side of the component. That means you can then wire both poles of the switch in parallel instead of series, which more or less eliminates the possibility of a failure.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • BeardyAndyBeardyAndy Frets: 716
    ICBM said:
    It's also wired in the worst possible way for reliability - with the signal passing through both switch poles in series - so even if it isn't broken now there's a good chance it will cause trouble at some point.

    To select two different component values, they only need to be switched at *one* side of the component. That means you can then wire both poles of the switch in parallel instead of series, which more or less eliminates the possibility of a failure.
    So as i'm looking at the image it should really be wired to the upper or lower leads?

    (i'm new to this game if you hadn't noticed!) :)
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  • ICBMICBM Frets: 71956
    BeardyAndy said:

    So as i'm looking at the image it should really be wired to the upper or lower leads?

    (i'm new to this game if you hadn't noticed!) :)
    One wire should be connected to one lead of both caps. The other lead of each cap should then be connected to both outer terminals at one end of the switch, and the other wire to both middle terminals.

    If you're switching cap or resistor values you can even do it better by using combined values, with one permanently in the circuit - failure proof. eg if you want to use .22uF and .47uF caps, use two .22s and use the switch to add the second one in parallel. (.44uF is effectively the same as .47.)

    So much that you see in guitar gear is not designed with apparently any regard for failure modes at all, and very often far more unreliable than it needs to be.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • BeardyAndyBeardyAndy Frets: 716
    @ICBM thanks for the advice, I think I know roughly where your coming from but just in case I’m going to pull the mod out and put a cap back in the board and make it as was from the factory. Once I’ve started to get my head around it i’ll probably have another go.

    PS-When I took the board out there was one of the mod wires un attached so I think Ive successfully diagnosed why it’d stopped working!
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  • BeardyAndyBeardyAndy Frets: 716
    So as a quick fix I used one of the caps off the knackered switch and fitted it to the board, works perfectly!

    Thanks all. :)
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  • FunkfingersFunkfingers Frets: 14321
    Some wah pedals do the cap switching with a rotary switch.

    https://i.imgur.com/Z8YPyLV.jpg

    This ought to be less prone to impact breakages and, in the event of one capacitor failing, you have others to get you to the end of your set.
    Be seeing you.
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