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did I fry my pots?

Discussion in 'Hardware, Setup & Repair [BG]' started by RyanHelms, Nov 17, 2003.


  1. RyanHelms

    RyanHelms

    Sep 20, 2003
    Cleveland, OH
    Here's a wiring mishap (and a lot of frustration) that may have been avoided by getting out the multi-meter first. I wired up my nearly completed P/J (volume-blend-tone) and had weak signal with some fuzziness.

    At first I thought the tone cap was bad, but figured that was remote. Knowing the signal leads were all correct, I started tracing down my grounding. After re-soldering I don't know how many times and moving things around, I finally put the DMM on the volume and tone pots. One was swinging wildly and the other was a dead short. There hadn't been any scratchiness when I did have signal to clue me in here.

    Either I fried the mini pots by putting to much heat on the shells, or I had bad pots to begin with. Which scenario it was I'll never know because I melted everything over and over again before checking with the meter. Moral to the story - get the meter out before plugging in the soldering iron. This is probably old news to most of ya, but maybe someone can save themselves a big hassle. Or get a laugh (more like a groaning laugh....)

    BTW, the new bass is sweet! (now if only I could plug it in) :rolleyes:

    -RH
     
  2. SuperDuck

    SuperDuck

    Sep 26, 2000
    Wisconsin
    I think anyone that solders should have a DMM sitting next to them. Considering how dirt cheap you can get them (and you're not even using all of the functions!), I don't see an excuse not to have one.

    Not to speak of quality, but at the Harbor Freight Tools by my house you can get a DMM for under $5! I mean, come on. :D Now, those are the cheap, credit card types, but still, it's better than nothing. The decent ones aren't that much more.

    Is your new bass a from-scratch project, or a retrofit, etc?
     
  3. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    As an electrial engineer, I have to say that damaging pots by heat from a soldering iron is pretty unusual...in fact I've never seen it done!

    Congratulations :rolleyes:
     
  4. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    I've melted my share of pots. Most of 'em were the cheap plastic kind though. :) But seriously folks, I've seen some bushings get wierd when too much heat is applied to them. As brianrost said, that would be a real accomplishment with an ordinary soldering iron, but who knows, in today's world I wouldn't put anything past the pot manufacturers in terms of cutting corners. Best to be careful. On "ordinary" pots (like the CTS kind), the trick is to use a "reasonable size" soldering iron, not one of those 100 watt jobs. Two things: one is, when soldering to the lugs, use only as much heat as you need to get a good solder joint, nothing more. Second thing, if you're soldering a ground wire to the pot case, use stranded wire and make sure to "tin" it first.
     
  5. Ive fried a pot or two before. Especially when it has a chunky gauge wire on it and it just doesnt want to whet with solder.

    If you are using fairly thing wire it should only take about 3 seconds per solder joint. ;)

    :D:D

    Merls
     
  6. RyanHelms

    RyanHelms

    Sep 20, 2003
    Cleveland, OH
    The pots were quality CEG mini's, no cheapo jobies. A local guitar tech told me the wiper material (?) breaks down from too much heat on the shell. I wonder what watt iron folks normally use. Mine's 25W. I grabbed new pots and used ring terminals to tie lugs/leads to ground on the cavity shielding. No more soldering on the shell for me. :D

    True about not fully using the DMM, I keep it around for continuity and DCv checks. Man, just for that though it's absolutely worth having! For example I found out the aluminum tape I used is not conducting from one piece to the next i.e. sides to bottom. Next one gets sheilding paint.

    Oh yeah, the new bass is a "from-parts" build. I ordered up an alder P body and a maple-ebony fretless neck, added a bridge J pup, and recut the horns and headstock. Start another thread in with pics? :cool: What forum?


    -RH
     
  7. SuperDuck

    SuperDuck

    Sep 26, 2000
    Wisconsin
    Most people stick between 15 and 30 watts. I have a 15 and a 30 and like using the 30 moreso. Someday I'll have one of them new-fangled adjustable temperature soldering irons. Look out.

    You can put pics of your new bass up in the Basses forum.
     
  8. Here's the trick with pots.

    Make sure you tin the legs first and the wire you wish to solder.

    Also, when it comes to soldering the ground wire to the back of the pot (or the top. whatever tickles your toes), grab a small file first. File it back a bit. This roughs it up and allows the solder to whet a bit better. Solder onto it first without the cable. Let it flow and have a blob there. remember. No more than 3 seconds. Let it cool for a few seconds. Heat the blob and bring the wire to it.

    Easy done. ;)

    :D:D

    Merls
     
  9. RyanHelms

    RyanHelms

    Sep 20, 2003
    Cleveland, OH
    Tin first und file de rough shpot ya, das ees goot!

    I'm liking the ring-terminal-over-the-pot-shaft-with-attached-lead approach. Very clean looking (although if you know how to solder to pot shells properly :rolleyes: that looks clean too) And a cinch to change. Cutting half the crimp connection away leaves a great little trough to fill with solder that can easily hold three lines.

    I think I know the one pot I fried fer sure that had the bridge lead, tone cap ground, and both pup grounds all in the same blob. Too much in one spot. A little more though and the ground leads could have been evenly spaced.
     
  10. Its all good experience. ;)

    Next time someone else posts up about rewiring you can say "no! dont do that! i made that same mistake!"

    And it saves me typing. sssshhhh hehe

    :D:D

    Merls