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Thread: Blues Pearl Blue Balls Pedal - Pot Issue

  1. #1
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    Blues Pearl Blue Balls Pedal - Pot Issue

    I recently bought a Blues Pearl pedal and the level knob has no resistance; you can move it by pretty much blowing on it. It makes it hard to accurately dial in a setting. It's also only scratchy when passing thru the 10-11 o'clock range.

    Any idea what could be wrong with the pot? It's not just a loose knob cuz the level value does change when turning the knob.

    I'm having trouble finding a schematic to find out what the pot value is, incase it needs to be replaced.

    Thanks.

  2. #2
    Supporting Member The Dude's Avatar
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    Before spending a bunch of time on it, try cleaning it.
    “Yeah, well, you know, that’s just, like, your opinion, man.”

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    Old Timer J M Fahey's Avatar
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    First clean it to kill scratching; if not possible you will have to replace it.
    We have no clue about what a Blues Pearl is, you post pictures and links.

    Pots in general have the value printed or stamped on them somewhere or a small pasted label.
    And you can *measure* them, of course

    Given what a pot costs, just get a new one.
    Juan Manuel Fahey

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    Quote Originally Posted by J M Fahey View Post
    We have no clue about what a Blues Pearl is, you post pictures and links.
    Blues Pearl BB-1 Blue Balls | Effects Database

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    Quote Originally Posted by Mustang Martigan View Post
    I recently bought a Blues Pearl pedal and the level knob has no resistance; you can move it by pretty much blowing on it. It makes it hard to accurately dial in a setting. It's also only scratchy when passing thru the 10-11 o'clock range.
    By "resistance", here you mean physical resistance not electrical resistance correct?

    If this is the case, check the back of the pot to see if the rear cover has been pushed off which will cause a loss of tension on the pot shaft in some designs.

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    Quote Originally Posted by 52 Bill View Post
    By "resistance", here you mean physical resistance not electrical resistance correct?

    If this is the case, check the back of the pot to see if the rear cover has been pushed off which will cause a loss of tension on the pot shaft in some designs.
    Yes, physical resistance. I'll definitely check that out. I looks may need to buy a socket driver; I can see a nut under each knob, and they need to be removed to open the chassis. Is the nut size usually universal?

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    Senior Member Enzo's Avatar
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    The knob must be removed first, of course. They either have a set screw or two, or they pull straight off.

    No, the nuts are not universal. US products like Fender with pot bushings 3/8" diameter mostly used a 1/2" nut. But MANY pots are asian in origian, and have metric nuts. I keep a 1/2" nut driver on my bench along with 9mm, 10mm, 11mm ones as well.

    But if you only need to deal with this, a pair of pliers will take the nut off just fine.

    Regular old slip-joint pliers would be my tool grab.
    j278_mid_res_2.jpg
    Education is what you're left with after you have forgotten what you have learned.

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    Quote Originally Posted by Enzo View Post
    The knob must be removed first, of course. They either have a set screw or two, or they pull straight off.

    No, the nuts are not universal. US products like Fender with pot bushings 3/8" diameter mostly used a 1/2" nut. But MANY pots are asian in origian, and have metric nuts. I keep a 1/2" nut driver on my bench along with 9mm, 10mm, 11mm ones as well.

    But if you only need to deal with this, a pair of pliers will take the nut off just fine.

    Regular old slip-joint pliers would be my tool grab.
    Click image for larger version. 

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    Ya, I'll probably just go with the wrench.

    As far as the value being printed on the back of the pot, I assume it won't say if it's a linear or audio taper. Do most level dials use linear?

  9. #9
    Old Timer J M Fahey's Avatar
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    Oh, usually they *do* say so, although sometimes using a letter or number code, not the full word.
    Typically, and just as an example, 100k linear will be 100k lin or 100kB or B100k ; while if Audio/log: 100 k log , A100k or 100kA .
    Reverse Log would be 100kC or C100k .

    Often numerical value is indicated by a number plus "quantity of zeros" so 100 k might be written 104 (10 0000).

    All because available space is small for full text in any readable size font.

    Absolute worst case, you measure them: set rotation to 5, halfway, what you measure end to end is pot value; if from center to each end both halves measure the same, itīs linear; if one half is 3 to 10 times larger than the othar, itīs Audio/Log.
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    Juan Manuel Fahey

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    Quote Originally Posted by J M Fahey View Post
    Oh, usually they *do* say so, although sometimes using a letter or number code, not the full word.
    Typically, and just as an example, 100k linear will be 100k lin or 100kB or B100k ; while if Audio/log: 100 k log , A100k or 100kA .
    Reverse Log would be 100kC or C100k .

    Often numerical value is indicated by a number plus "quantity of zeros" so 100 k might be written 104 (10 0000).

    All because available space is small for full text in any readable size font.

    Absolute worst case, you measure them: set rotation to 5, halfway, what you measure end to end is pot value; if from center to each end both halves measure the same, itīs linear; if one half is 3 to 10 times larger than the othar, itīs Audio/Log.
    Would those measurements be taken with a Multi-Meter? I own one, but I'm not very experienced with it.. I'd have to google how to set the meter up for an accurate reading.
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    Old Timer J M Fahey's Avatar
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    Ok.
    I bet there are a couple YT videos out there explaining how to use a Multimeter, try to lean because itīs an incredibly useful tool.
    That said and as a micro-course: multimeters can read many things (thatīs what "multi" means ) , so you must first tell it first what are you interested in.
    This is the most generic one and you select what you want with a rotary switch:


    Ideally you should pull your pot from the PCB but sometimes mesuring still mounted (with pedal OFF and without supply or battery, just in case) can give you useful results.
    Pot has 3 legs:


    1) you set multimeter to measure resistance.
    The position you select means you can read "up to" what is indicated.
    In principle I suggest the 2000k position, meaning screen can display "up to" 2000k ohms ... to be more precise 1999 k ohms.

    2) you ut the potentiometer on the table, legs pointing down as shown (towards you) , rotate shaft half way between full left and right, and measure resistance from end to end, or pins 1 and 3 as shown.
    Screen will show some number.
    Suppose it displays "112" ... it means 112k ohms, so the pot is nominal 100k ohms.
    Why?
    Because all ellectronic components have some "tolerance", meaning values are not *exact* (they would be horribly expensive if so) and in any case that is usually not that important.
    Often 20% tolerance is fine , so expect a 100k labelled potentiomener to show anything between 80k and 120k. no big deal.
    You measure actual value and pick which "standard" value best describes it.

    3) as of Lin/Log stuff:
    measure from center leg to left one, then from center to right one.
    * if both roughly 50k: linear.
    * if left somewhere around 10k (in some Fender pots might be as high as 20k or 30k) and right what is needed to complete 100k, itīs Log/Audio.
    * if high resistance is on left and low resistance on right (always with legs oriented as shown) itīs Anti Log , Reverse Log, quite unusual but needed in some Distortion or Boost pedals (MXR Dist+) or some SS Fender preamp gain controls, so itīs not impossible to find it.
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    Juan Manuel Fahey

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    Quote Originally Posted by J M Fahey View Post
    Ok.
    I bet there are a couple YT videos out there explaining how to use a Multimeter, try to lean because itīs an incredibly useful tool.
    That said and as a micro-course: multimeters can read many things (thatīs what "multi" means ) , so you must first tell it first what are you interested in.
    This is the most generic one and you select what you want with a rotary switch:


    Ideally you should pull your pot from the PCB but sometimes mesuring still mounted (with pedal OFF and without supply or battery, just in case) can give you useful results.
    Pot has 3 legs:


    1) you set multimeter to measure resistance.
    The position you select means you can read "up to" what is indicated.
    In principle I suggest the 2000k position, meaning screen can display "up to" 2000k ohms ... to be more precise 1999 k ohms.

    2) you ut the potentiometer on the table, legs pointing down as shown (towards you) , rotate shaft half way between full left and right, and measure resistance from end to end, or pins 1 and 3 as shown.
    Screen will show some number.
    Suppose it displays "112" ... it means 112k ohms, so the pot is nominal 100k ohms.
    Why?
    Because all ellectronic components have some "tolerance", meaning values are not *exact* (they would be horribly expensive if so) and in any case that is usually not that important.
    Often 20% tolerance is fine , so expect a 100k labelled potentiomener to show anything between 80k and 120k. no big deal.
    You measure actual value and pick which "standard" value best describes it.

    3) as of Lin/Log stuff:
    measure from center leg to left one, then from center to right one.
    * if both roughly 50k: linear.
    * if left somewhere around 10k (in some Fender pots might be as high as 20k or 30k) and right what is needed to complete 100k, itīs Log/Audio.
    * if high resistance is on left and low resistance on right (always with legs oriented as shown) itīs Anti Log , Reverse Log, quite unusual but needed in some Distortion or Boost pedals (MXR Dist+) or some SS Fender preamp gain controls, so itīs not impossible to find it.
    Thanks for the info; gonna open up the pedal this weekend. That multimeter looks exactly like the one I have, except it's red, not yellow.

    Oh ya, one more question.. are any of you familiar with the differences between the original Blue Balls and the reissue? From the pics I've seen online, there are two models that are a lighter blue color and have all three knobs lined up horizontally. Then there's a third model, the one I have, that's a darker blue and the 3 knobs are in a V shape. Is there any kind of sound difference or is it purely cosmetic?

    I played one at a store 8-10 years ago (I can't remember which of the three models it was) and I remember it sounding much more brutal.. more like a straight distortion, rather than that one I bought, which is a kinda harsh sounding overdrive pedal. I don't think the problem I'm having with the level pot is affecting it's sound.
    Last edited by Mustang Martigan; 11-25-2017 at 12:53 PM.

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