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Soldering ground wire to mini-pots w/o frying them?

Discussion in 'Tele Home Depot' started by V Silly, Mar 17, 2018.

  1. memorex

    memorex Friend of Leo's

    Age:
    68
    Jan 14, 2015
    Chicago
    I don't solder to the backs of mini-pots any more. I use these solder lug washers instead. It works just as well, and I never heat damage the pots. It's also easier if you have to swap out the pot.

    [​IMG]
     
    Zepfan and Humble Pie like this.

  2. OneHenry

    OneHenry Tele-Holic

    Age:
    62
    568
    Apr 16, 2018
    North carolina
    I use a wet cellulose sponge or damp paper towel to clean soldering iron tips. Damp cotton cloth also works well to clean a soldering iron tip. The cloth can't contain a plastic fiber, such as polyester or nylon, or it will melt. A piece of cotton t-shirt, cotton bed sheet, cotton wash vloth, cotton towel, or cotton diaper (no polyester) works well. I have also used red cotton shop rags. Most good soldering iron tips are iron plated, sandpaper will remove the iron plating, which is a Bad Thing. Make sure that you keep a thin layer of solder on iron plated tips so that they don't oxidize/rust.
     

  3. Ronkirn

    Ronkirn Doctor of Teleocity Vendor Member

    Age:
    71
    May 1, 2003
    Jacksonville, FL
    OK, without reading everything, because it's all been said before... punctuated by some plain old incorrect info.. so....

    The makers of the potentiometers know that often the case is used as a ground (earth) point, so all of them are made worth cases that are designed to be receptive to soldering... thus no need to sand, scrape, unless it's one, a really dirty pot case. A few very esoteric pots can have cases made of metals that are not receptive to solder, no amount of sanding or scraping will solve that.

    the next thing is heat hits the pot case much like if you took an "eye dropper" and dripped water into the middle of a paper towel... assuming you needed a spot that was soaking wet... if the drops were small enough or distanced far enough apart, the water evaporating could prevent the towel from ever getting wet enough to accomplish what needed to be accomplished..

    SO if you needed a small soaking wet spot, but could not allow the remaining paper towel to get too wet...the dropper would not be sufficient to accomplish the task.. And a class of water would not be correct either simply because you could not regulate the amount of water to get a small spot soaking, bit keep the edges dry enough...

    Use a tea spoon... it "blasts" the small area, getting it wet enough... while not supplying too much water to make the whole thing soaking....

    Similarly... using a soldering tool that is too small, say 20 watts, can warm the center of the pot's case, but the rest of the case "soaks" away the heat fast enough that the target spot never gets hot enough, in excess of 400 degrees F, to create a secure solder connection./.BUT.. IT does supply enough heat that the case can heat it entirely to a point that becomes detrimental to the internal components of the pot, often plastics.. results.. fried pot.

    If you use a more robust tool it can heat the spot to the necessary temperature to accomplish the molecular adhesion, without requiring you leave the tool in contact long enough to heat the whole thing.

    Nest you do not touch the solder tool to anything until it's hot enough to accomplish the goal..if you apply the "cool tool and wait for it to get hoot enough to melt the solder.. same thing as with the water illustration.. the case is "soaking' away the heat as it is warming.. resulting in a fried case..

    Next thing.. DO NOT touch the solder to the tool tip melting the solder and let it "drip" onto the connection... wrong, wrong, wrong, wrong, wrong, wrong, ... if it DOES stick.. it will be the flux, or resin that is acting as a glue.... it is not solid, it is not permanent, it is not electrically conductive.. The connection will inevitably fail right as the band leader looks at you and says “Take it." while simultaneously the long legged redhead in the black leather mini's eyes meet yours, she smiles seductively… and your guitar utters that enticing sound.. Gruntttpppfpttummmpf... Bzzzzzzpppptttttttt….

    another thing.. use the correct solder... if you found it in the plumbing department.. Wrong.... you need ELECTRICAL solder...

    and do NOT learn on your CS Tele.. find some one electronic junk=, an old power supply supply from an old computer is perfect.... solder and unsolder contacts in that until you feel confident...then throw it away..

    rk
     
    John Nicholas likes this.

  4. Davecam48

    Davecam48 Friend of Leo's Gold Supporter

    Age:
    70
    Dec 31, 2009
    Queensland Australia
    :lol: Ron I just love your turn of phrase!!!!!! I have made a few posts regarding the correct method of soldering just as you more colourfully describe above, but I guess there are always beginners.
    I used to work in the hearing aid industry and trained a lot of techs to solder looking through a microscope .........picture a printed circuit board about a 1/4" square and having to solder three or four wires to it without shorting out or overheating the board.

    Some could do it ..........some could never do it. One chap I interviewed for a tech job was so hyped up by soldering at that level, his hand was shaking about three inches either side of where the tag was and had a few "dabs" with the iron but never hit it once. He was so nervous I thought he was going to have a stroke.

    DC
     

  5. Ronkirn

    Ronkirn Doctor of Teleocity Vendor Member

    Age:
    71
    May 1, 2003
    Jacksonville, FL
    yep I can recall trying to teach audio "grips" at our TV station how to solder something as basic as a Canon XLR connector to a piece of lo Z Mike cable... jeezus, you would think they were called up to do impromptu brain surgery...they were shaking so bad they were slinging hot solder all over the place...

    rk
     

  6. robt57

    robt57 Telefied Ad Free Member

    Feb 29, 2004
    Portland, OR
    And/or just dirty/contaminated causing same convection short coming.

    Then there is finding really old solder in your drawer when the iron is already tinned with the new stuff. That has got me once or twice over the years. I miss my old real lead stuff sometimes. ;)
     

  7. Zepfan

    Zepfan Poster Extraordinaire

    Nov 30, 2013
    Horn Lake, MS
    I started soldering grounds to the side of pots years ago. Always good to sand/file/scuff the area first. Flux helps.
     

  8. tele_savales

    tele_savales TDPRI Member

    Age:
    52
    16
    Apr 30, 2018
    Brooklyn, Joey!
    I'm seriously NOT an expert, but here's what I've learned after a ton of mistakes and which I'm sure everyone has touched on.

    Start w a brand new tip and tin it. Never sand it, wipe it on a wet sponge between every join. It may help to start w a chisel shaped tip. When you're done soldering and wipe it on the sponge, it should be shiny.

    I sand the back of pots for about 5 seconds w 320 grit paper. It helps.

    I have an adjustable iron that I set at around 325 degrees for soldering switches, and bump it up to around 400 for getting a nice pool of solder on the back of pots. But I am greenhorn and I've torched a few switches so take that w a grain of salt.

    Pre-tin EVERYTHING, pots, lugs, wires and especially if you're trying to solder braided shield to the back of a pot.

    PRACTICE!!! Practice on pots and switches that you've ruined. Try to get on and off every connection in about 2 seconds.

    I've found that mounting all your parts on a small cardboard box helps immensely on keep things from moving around, then mount it in the guitar and finish your connections.

    There are some really great tutorials on you tube, that will help a bunch.

    Have fun!
     

  9. Vizcaster

    Vizcaster Friend of Leo's

    Sep 15, 2007
    Glen Head, NY
    Ok so go back and please re-read Ron's posts. I was already thinking that 'sanding' the back of the pot is outdated and no longer good advice. it's an old-school idea but in our lifetimes new pots will already be tinned so you shouldn't sand.

    If I had anything to add, I'd suggest using a small drop of flux (you can get it in a small tube or sometimes a plastic syringe looking contraption). if you put the flux on the pot, then heat it with the soldering iron tip, it should etch the surface and usually makes it shiny silver colored - then you can continue heating the local area and apply enough solder to make a tiny, shallow blob (not a Hershey's kiss thick cold blob). that's how I pre-tin the pot, just as you would pre-apply some solder to the stranded wire before trying to make up the connection. Then both pieces have some solder and you don't need to add much more solder once you heat the two.

    And always use a chisel-tip for this application; the cone shaped tips are for much more delicate work like printed circuit boards.

    And along the lines of "more gear must be the solution," get a small tin of soldering iron tip cleaner. if the tip is oxidizing then try leaving a blob of solder on it as you put it back into the holder - you want to use the sponge or bronze-wool cleaner just before soldering a connection, not after you're done. it needs to be clean for the connection, but covered with solder when waiting between connections.
     

  10. s_tones

    s_tones Tele-Holic

    788
    Nov 10, 2013
    central CA
    I have read (and implemented) the technique of NOT soldering grounds to pots. Instead I have grounded the pots by having their bodies abutting a “metal housing” which in my case consists of the copper foil cavity lining which serves as a common ground the way a metal component case would. Seems to work just fine
     

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