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Bass Potentiometer

Discussion in 'Pickups & Electronics [BG]' started by the_observer, Oct 3, 2013.


  1. the_observer

    the_observer

    Oct 3, 2013
    Hey guys,


    I was wondering if there are anyone out there that can help me with this issue.

    This bass that i've got doesn't produce any sound, and i have a feeling that there's something wrong with the pots. I've tried measuring them with a multimeter and the results produces are weird?


    Anyways,

    500k A pot @ 4M resistance shows: 0.010 on multimeter
    50K B pot @ 400K resistance shows: 29.1 on multimeter
    other 50K B pot @ 400k resistance shows 29.8 on multimeter


    :/


    help please!
     
  2. RadioRob

    RadioRob

    Dec 15, 2012
    We have questions for you.
    What kind of bass?
    Did it just happen?

    Well if you have the wires exposed just by pass the pot with a short temp jumper wire.
    This will make it full volume. Then you will know. You might have to jump both depending how its wired.
     
  3. mrbell321

    mrbell321

    Mar 26, 2012
    N. Colorado
    I don't really know what you're trying to say...
     
  4. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    What setting is the multimeter set to? Are the "at 400K" or 4M your settings, in the DC resistance section?
     
  5. davens

    davens

    Jan 24, 2005
    Stoney Creek, ON
    Your readings indicate 10K, 29.1K, 29.8K on the 3 pots respectively. I assume you're measuring between the two outside pins of each pot, in circuit. My guess is this is an active bass with passive pickup(s) since there are 50K pots? You can't accurately measure the resistance of a POT while it's in-circuit since the pickups and other components will greatly affect your reading. My best recommendation is to connect the pickup directly to the output jack and disconnect any other circuits to make sure the pickups are OK.
     
  6. mrbell321

    mrbell321

    Mar 26, 2012
    N. Colorado
    OH!
    I know what he's saying...
    500k is the pot rating. Multimeter is set to 4M Ohm range and it's reading 0.010 or 10k Ohms
    50K is another pot rating. Multimeter is set to 400k range and is reading 29.1 or 29.1k ohms
    another 50k pot reads 29.8k

    And, just to make sure, you're reading across the outside terminals?
    It sounds like your 500k pot is toast. Shorted out.
    The 50ks are reading low too, but significantly less bad than the 500k.
     
  7. davens

    davens

    Jan 24, 2005
    Stoney Creek, ON
    mrbell321,
    500K pot is not necessarily toast. If this is a volume pot, still connected to a pickup with DCR of 10~15K, with volume up, the reading will come out to 10K. You can only accurately test individual components when they are isolated from the circuit.
     
  8. mrbell321

    mrbell321

    Mar 26, 2012
    N. Colorado
    OH, that's a good point. I assumed they were isolated. They should be isolated :)
     
  9. eddododo

    eddododo Supporting Member

    Apr 7, 2010
    wait...
    wouldnt there be some parallel resistance, what with the pickups themselves and the rest of the circuit?

    edit:
    read the last posts, ed.. :rollno:
     
  10. the_observer

    the_observer

    Oct 3, 2013

    Yeah. that's what i meant.

    It's a yamaha rbx765a.

    I did not isolate it. It was soldered on to a small circuit board.

    photo.

    I acquired this bass from a mate and apparently its been like that for a year and he just never got around to fixing it.


    so, how do i go about trouble shooting?
    do i have to de-solder every pot and test it? or is there another way around?
     
  11. No sound is very rarely an issue with pots. Sounds like there is a cold solder joint, or a preamp issue.
     
  12. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    That's a good point actually--all this business about the pots and the multimeter was kind of missing the boat.

    OP, have you changed the battery? Does it really make "no sound" or is it very quiet, or is there a hiss or hum? If you wiggle the various wires and parts while the bass is plugged in, are there any crackling, popping, or other intermittent sounds? Any noises when you plug the cable in/out?
     
  13. the_observer

    the_observer

    Oct 3, 2013
    Haha. Please excuse my noob-ness. First time i'm dealing with these electronics. :(

    I put in a new battery, and plugged it in. And there isn't a sound at all. Shook the wires and components a little, still nothing. There is that normal pop you get when plugging it in and out.
     

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