HELP! Need to know what pots to buy!

Discussion in 'Pickups & Electronics [BG]' started by Stu_Bacca, Dec 25, 2014.

  1. Stu_Bacca

    Stu_Bacca Guest

    Dec 25, 2014
    Hello guys,

    First time Post here. My bass has been playing up on me for a long time now. All the knobs give a crackling sound when your turning them and hiss and pop. As well as this the sound completely cuts out now sometimes as well, with the resolution being a hefty whack on the back of the body! All i can tell is that there is only one volume knob from what I can tell. Im guessing the other 3 just are tone knobs of some kind. My worry is that its already been Frankensteined! No readable info on the pots! Wiring looks a bit dodgy! The bridge and saddles and machine heads are oxidised so it was obviously Stored somewhere damp at some point!

    I bought this bass with a hard case for 120euro as my first to learn on, and its still my only bass. I love the action and the feel of it and would love to get it 100%!
    It's a 5 string Active Dean Bass. No model number anywhere on the bass! I think its a PJ bass!? I use it to play slap bass mostly. Les Claypool Would be one of my biggest influences.

    Now.... Ill attach photos of my bass, I cant figure out what parts I need as there are just too many options! I have no idea if I should go passive instead for slapbass? Either way it needs gutted and sorted! Any help would be most greatly appreciated. I am not used to working with basses but I am used to working with soldering irons etc so I should be able to handle this project! I need help to know what parts to buy. I would be willing to replace the pick-ups and all if I was told it was worth it! Is the oxidation on the bridge be affecting the sound badly?
    There is literally no good shop anywhere near me at all here in Donegal.
    Last edited: Dec 25, 2014
  2. I can't tell for sure from the pictures, you might have one volume pot, a balance pot, a bass pot, and a treble pot. Now it seems you have a couple of different issues. The cutting in and out that you fix by whacking it hard--probably a cold or broken solder joint. That battery connector looks cobbled together too. You might even have a capacitor with a broken leg.

    The crackly could try getting a spray can of Deoxit and spraying inside them. That often can help crackly pots. If you need to replace them, though--well, how good are your soldering skills? What test equipment do you have?

    If I had that bass here on my bench, and needed to replace the pots, I would start by physically measuring each one--the new pots must match the body diameter, the screw thread size and length, and the shaft size. They must match the pin configuration too, to connect into the PCB. Then I'd determine the electrical value for each pot. Are they audio taper, 500K pots, for example, and is one of them truly a balance pot.

    Another option would be to do away with that preamp and convert it to a passive setup. You could make it V/V/T/T with those four knobs.

    Oh, and shield that control cavity.
  3. walterw

    walterw Supportive Fender Commercial User

    Feb 20, 2009
    +1 to first spraying de-oxit into the pots to clean them up, that's often all that is needed.

    then, check and maybe replace the jack and that battery clip.
  4. bassbenj


    Aug 11, 2009
    Ok. Bass electronics lessons!

    1. First thing to try with crackly pots is spray pot cleaner. The poof can comes with a long tiny tube and the place to try to get it into the pots is hopefully there is a gap just above the contacts on the phenolic board with the 3 terminals. Otherwise you might try the indent on the back of the edge of the case. Often there is an opening there.

    2. This is an active bass and pots are mounted on the circuit board. This means that standard pots are not direct replacement. It also means that the pot values may not be standard values. Best would be be a replacement set of pots from bass maker, otherwise you'll need an ohm meter to measure the value ONCE the pots have been REMOVED from the circuit board. Scratch the Ohms on each pot back. Note value is the ohms between the two OUTSIDE terminals.

    3. Don't just guess. Figure out what each pot does. You do this by taking a small screw driver or paper clip to tap on the pickups. Doing that figure out which pots are volume and if they are volume/volume or volume/blend. Since this is a P/J configuration it's doubtful that you only have a single volume pot. The other two pots will be "bass" and 'treble" controls. The way you figure those out is by plucking the G string with your fingernail and seeing which pot rolls off the highs or boosts them. The bass is the other one, but it might be easier to test by plucking the B string (or E string you have a string missing) and seeing which pot makes the lows louder and softer. Write down which pot does what in a diagram and scratch it's function on the back (maybe even put labels on the circuitboard near the pots.

    4. At this point take off the knobs (set screws or if there are none, they pull off) and take nuts off pots. Pull whole board assembly out of bass. See how pots are mounted to board. If they are just tightened on the board with nuts on the shafts this is good. If they are all soldered on the board with tabs, that is not so good.

    5. Buy a solder sucker. (It's a plunger vacuum thingy with a trigger...essential for what you are about to do.)

    6. Remove the four pots (you marked them and where they go right?) from the board. You do this by heating each long pin from the pot where it goes through the board and suck the solder out of the hole in the circuit board until the pin is loose and free. When all 3 are free, remove the pot.

    7. Once you have the pots removed, measure the ohms on each one. Go on line to electronics supply (like Mouser) and try to find pots of same value with PC pins. This may or may not be easy. Usually you'd pick linear taper for all except volume which will be audio. Linear taper for all of them shouldn't be that bad if it's all you can find. Wrong taper will show up as full action of pot over just a limited rotation. I wouldn't worry about that at first.

    8. If you can't find PC mount pots then buy pots with normal solder terminals and you'll have to run wires from the pot terminals into the proper holes in the circuit board for that pot.

    I know this sounds complex but it really isn't. Once you go through it, you'll be ready for anything. If possible I do not recommend switching to passive because this is a PJ 5er bass (sweet!) The P-bass pickups and the J pickup will not balance well in a passive circuit. ( I know since I have one!) Active allows them to balance correctly.

    Consider shielding if cavity does not already have conductive black paint.

    Good luck.
  5. Stu_Bacca

    Stu_Bacca Guest

    Dec 25, 2014
    Thank you for your posts. And so quick at this time of year! ¦0)

    I'm used to soldering motherboards from laptops so you can safely assume my soldering skills are good.
    I have a solder sucker and all necessary tools for that work.

    There was a lot of info there. I'm going to begin by buying a can of this "Deoxit" and see what happens with the crackly pots. (Ordering today)
    I have a feeling that they will need replaced. They feel gritty for lack of a better word. Maybe I'm hoping they need replaced a little.
    In my head I've somehow convinced myself that it will make it so much better!

    Is it worth buying a set of new pick-ups first and working from there? Or is that getting ahead of myself? Or are these Pick-Ups good enough?

    I've now realised that wiggling the battery make the cut-out thing happen so hopefully replacing the battery connector will sort that.

    As for my Bridge and saddles, Will the roughness of them effect my sound much? I'm at the point now (playing 8 years) that I want the
    best sound I can get out of this bass, sustain is important as well? Or will this spray work on them or is that silly?

    Thanks again
  6. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    Westchester, NY
    Don't worry about that yet. Figure out what needs to be fixed before you toss money into it. If you replace the pickups you'll still have the same issue you started with.

    Detoxit is an electrical component cleaner. It will do absolutely nothing for your bridge and saddles.

    -Fix the electronics
    -Get a new set of strings (do you have the 5th string removed for a reason?)
    -Get a setup on the bass

    Once those are done the bass will essentially be the best it's going to be in it's current state (assuming it's a good setup). Then you can decide if you want to bother swapping parts. Me personally? I'd probably sell it and get something that better suited what I wanted from a bass.
  7. Stu_Bacca

    Stu_Bacca Guest

    Dec 25, 2014
    Thank you again for your reply, and sorry for the silly questions! ¦0)

    5th string just broke. Thought I would sort it before restringing. Have the strings here though. Still waiting on Deoxit though!

    Got more info on the pots. After a long time of fiddling and cleaning I managed to read some info off three of the pots.

    When looking at the back of the bass: (Pics 2 and 3)

    (A100K) (??) ---> think this one has "J5 or J6" on its side in black writing?

    (B100K) (B100KA)

    Fairly sure that I could read it well enough to get the three right? Does that seem right?

    Also I have now realised from trying to clean with what I have that three of the knobs have a middle stop point.
    They lock in place at the mid point of the turn. Obviously not the volume pot though!!