Pot switch question

Discussion in 'Pickups & Electronics [BG]' started by Egbert89, Jan 23, 2013.


  1. Egbert89

    Egbert89

    Joined:
    Aug 30, 2012
    Hey guys,
    A guitard friend has a london city comet (a really proper tele copy) with a bad 3-way switch(it doesn't latch anymore) and tone pot(he can turn all he want, nothing happens, he does have sound though no cracks or anything).
    I can solder and I'm discussing with him what pot/cap he'd want for replacement (we will probably end with something standard, 250K lin fender pot and 0.047uf cap).
    In terms of diagrams I'll just make a picture of the before situation and solder the wires in the same positions on the new pot/cap and switch.
    My question: Do you guys have any tips about the soldering in terms of dissipating the heat so that I do not fry something. Or shouldn't I be afraid for that? And maybe share some thoughts on proper soldering techniques. I know I can get the job done but it is always interesting to hear how other people do it. There's always room to learn!
    Thnx in advance!
    Egbert
     
  2. Cadfael

    Cadfael

    Joined:
    Jan 4, 2013
    Location:
    Germany, EU
    Hi Egbert,

    tone pots are normally log. pots!
    The .047µF is okay.

    You can also change the capacitor first and see what's happening. Maybe it doesn't need a new tone pot. A linear ton pot normally works nearly as an ON/OFF switch.
     
  3. Stealth

    Stealth Supporting Member

    Joined:
    Feb 5, 2008
    Location:
    Zagreb, Croatia
    The way I was taught was to mechanically overlap the wire and the contact, let the soldering pen (at least 40 W) heat up to its proper temperature, hold it on the pad/prong/contact you wish to solder to for three or so seconds, then press down with the solder so it melts and flows over the wire and the pad. Blowing into the solder to cool it down after you remove the pen supposedly does harm, so I just let it air-cool for ten seconds or so.
     
  4. Egbert89

    Egbert89

    Joined:
    Aug 30, 2012
    Ok, thanks for the info. Anything I should keep in mind ordering a cap, certain brand or sth?

    And why is it that a lin tone pot works nearly as an ON/OFF switch? Could you explain it on a more technical level?
    Because the way I see it (probably wrong haha) if you'd make a graph of it a linear distribution which goes from the same values (0 to 250K right) as a log scale (both in a straight line).
    The linear graph would just give a linear response so an overall balanced control (that was my assumption)
    Whilst with a log scale, the response would be more touchy in the low figures and less touchy the higher the resistance.
    Or aren't the log pots responses made exactly as logarithmic graphs I had in school? :help:

    Ok, thanks for the info :)
     
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  6. Cadfael

    Cadfael

    Joined:
    Jan 4, 2013
    Location:
    Germany, EU
    Hi Egbert,

    in Germany we call the capacitor question a "hot iron". You burn your fingers, touching it...
    Some say it matters. "Orange Drops" are often mentioned. Other say it doesn't matter (and I belong to the second group). I can only say that Leo Fender definitely used "what he could get cheap". Most bass capacitors had the same value (.1 or .05µF) but the % could vary from 5% to 20% and also -20/80 can be found ...

    I wrote "Cadfael's kleine Bass Schaltplansammlung" (Cadfael's small bass wiring compilation) which has nearly 400 pages with more that 300 examples now. But I am no skilled electronic. So I can not explain the technical background details.
    What I can tell is that the human ears doesn't work linear! Neither with frequencies, nor with loudness. So, to let something "sound / feel linear", I has to be logarythmic ...

    Most people are satisfied with linear volume pots. For volume you can use both. Depends on what you like. But tone pots are normally log pots.
     
  7. Egbert89

    Egbert89

    Joined:
    Aug 30, 2012
    Hey Cadfael
    Thanks for the information, do you by chance have schematics for a london city comet?
     
  8. Cadfael

    Cadfael

    Joined:
    Jan 4, 2013
    Location:
    Germany, EU
    No, I haven't ...
    I know that London City built amps and cabinets.
    Didn't know that they built bass guitars! Or is it another company with the same name?

    Photos appreciated!
     
  9. Egbert89

    Egbert89

    Joined:
    Aug 30, 2012
    Here you go: [​IMG]
    snapped it of my friends facebook haha
     
  10. Cadfael

    Cadfael

    Joined:
    Jan 4, 2013
    Location:
    Germany, EU
  11. Egbert89

    Egbert89

    Joined:
    Aug 30, 2012
    Ah I thought that was clear from the first post haha
    Thanks for the link!!
    Can't seem to download the PDF though
     
  12. Cadfael

    Cadfael

    Joined:
    Jan 4, 2013
    Location:
    Germany, EU
    Which browser do you use?

    Just click the link "F-Telecaster-Schaltungen-263.pdf" at the end of the page. A new window opens and you have to wait a bit because the file had nearly 6MB.
    When the file is downloaded, you can save it on your hard disk ...

    If you still have problems, send me a short PM with your email address. I will send you the pdf via email then ...
     
  13. Egbert89

    Egbert89

    Joined:
    Aug 30, 2012
    I use Google Chrome,
    but oddly enough it did work this time:D
    Thank you very much and might I add: WOW that is an amazing job you did there!!!
     

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