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HELP: Mini Tone Pot?

Discussion in 'Pickups & Electronics [BG]' started by OmegaZ27, Jan 17, 2006.


  1. OmegaZ27

    OmegaZ27

    Sep 18, 2005
    California
    Alright. I just recently bought a Fender Prophecy (which I love a lot) and I accidentally broke part of the shaft on the tone pot. It's no biggie and it still plays with no prob. It just annoys me because the knob still stays on but it's all crooked.

    I'll post some pics later, but I was wondering if anyone knew where I could get specifics on what type of pot it is or where I can get one? I found mini tone pots on Guitar Electronics, but I'm not sure what I should get because I dont have the specific pot specs. Plus, this Bass was made in 1994 and I have no parts list. So... can anyone help?:meh:
     
  2. OK, lets go at it this way: assuming your bass has passive electronics, which I suspect it does considering your mention of a single tone pot. What you're going to want to do is open up the control cavity, either by removing the plate on the back, if there is one, or removing the pickguard or control plate on the front, whatever it takes to be able to see the bottom of the pots. Now look at the one that is in need of replacement and it should have either "250k" or "500k" or some variation thereof stamped on the bottom. Its either going to be a 250 or a 500 on there. Then go down to any guitar store that does in-house repairs (and even some that don't) and buy yourself a new one of the same value (250 or 500 kilo-ohms). They're only a couple bucks. After all that, go home, take out the old one by heating the solder joints with your soldering iron, and then put the new one in exactly the same as the old one. It may help to make a little diagram before you start changing anything so you know how the thing should be connected in the end. Or if nothing else, have a shop do it if you don't feel comfortable with your skills. Good luck.
     
  3. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    I had a set of Prophecy III pups/harness/preamp once but don't recall details. Typically Fender pre's have PCB's mounted to the pots and if thats the case, you probably either need to locate a competent tech or think about looking for another pre if you don't have a backup bass, as the PCB would need to be removed from that pot and resoldered to another - NOT a beginner project.

    If there's no PCB (printed circuit board) on the pot, the pot should have all the specs you need written on the side or potback. Fender pots usually have short stems and large diameter threads, so if you buy a pot, ideally you want the same. If it's a taller stem smaller diameter thread, it will work but require some makeshift shimming and a spacer.
     
  4. OmegaZ27

    OmegaZ27

    Sep 18, 2005
    California
    Well, yes, it's active, and it does have a PCB on it, but wouldn't that mean if I canged that PCB, I would have to change the other PCBs on the other pots? That's gonna be a lot for me. I looked at the pot and it looks like a standard mini pot, but it has another pin right on the bottom of the pot.
    [​IMG] Just imagine this pot, with another pin on the bottom.

    I've been looking everywhere for a wiring diagram and I'm still unsuccessful. I also was looking everywhere for different pots and still unable to find that specific one. :help:
     
  5. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    don't understand what you mean by another "pin" on the bottom of the pot - a wire, contact into a main PCB?

    I was refering to a PCB that is actually soldered to the pot - like an EMG BTC (see emg site). If the pot has no PCB soldered to it then just replace that pot with the same. If it does have a PCB soldered to it, you'd have to transfer that PCB to a like pot (or solder the new pot to a main PCB). Nothing else would need to be changed.

    Another thing you might be able to do if you've got the piece that broke off is get some contact cement and glue it back in place.

    If the knob has a set screw in it, maybe you've got the set screw set into the broken side of the shaft and if you can get it to contact an undamaged portion of the shaft it, may align correctly. If it's a press on knob, maybe you can find one with a set screw that will work.

    Try the Fender site for a diagram. They have probably 30 or more of their basses diagramed there.
     
  6. OmegaZ27

    OmegaZ27

    Sep 18, 2005
    California
    Alright. I finally realize what this extra pin is. The whole pot has pins/contacts that go into the pcb. In the pic above, you see there are 3 pins. These pins would stick straight out and not be angled. This goes into the PCB. This pot is replaceable, but it's an unusual pot because there is another contact on the bottom that goes straight into the PCB also. I'm assuming that this is a ground contact??? Can I just get a replacement mini tone pot and solder a ground wire to the body of the tone pot?
     
  7. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    In all probability it is a ground and a ground is a ground.

    I would NOT attempt to remove that pot from the board yourself - unless you could as easily take waffle head framing hammer to the entire premap.

    You need experience and some solderwick (or the equivalent) or you can trash that board. I would find someone whose competent and get a price.
     
  8. OmegaZ27

    OmegaZ27

    Sep 18, 2005
    California
    Alright. So I assume that I could replace it with a standard mini tone pot right? All I would need to do is put the pot on the board and then just solder a wire from the body of the pot to the board.

    I read the pot and it reads M20k. I've seen 25k, 50k, 100k, 250k, and 500k on GuitarElectronics.com. Will it really matter with which one I go with for TONE?

    I don't need to worry about soldering because my dad can solder with no problem.

    BTW, thanks so much for your help!
     
  9. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    25K audio (which even music stores usually stock) would be close enough and get the job done.

    These previous comments bare repeating:

    Fender pots usually have short stems and large diameter threads, so if you buy a pot, ideally you want the same. If it's a taller stem smaller diameter thread, it will work but require some makeshift shimming and a spacer

    I would NOT attempt to remove that pot from the board yourself (or your dad unless he's done it successfully before) - unless you could as easily take waffle head framing hammer to the entire premap.

    Anybody can desolder and solder a lead to a pot lug. Quality soldering of a ground to a pot back can be a challenge and virtually impossible without a hot enough iron. Common sense will tell you removing a multiply connected component from a PCB is not for the inexperienced.

    How are you going to remove a soldered lug from board while you still have two lugs connected or heat up a second lug (let alone a third) before the first one sets, all the while there's heated contact with that board the more probility there is for damage to it?

    Ask your dad the same thing. If neither of you thought of that in advance, you might want to find somebody else that not only knows that in advance but has done it successfully on numerous occassions.

    I'm not joking about the hammer. You don't go into a Casino without as easily setting the money on fire and you don't try to remove components from a PCB without being willing to accept that it may be destroyed in the process rather than fixed. At this point, the PCB is not broke, there's nothing wrong with it.

    In fact, the bass apparently functions fine - it just has a crooked knob.