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Random thoughts on soldering

Discussion in 'Shock Brother's DIY Amps' started by King Fan, May 22, 2016.

  1. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Soldering ideas from a recent learner will not do a thing for all you pros here. But being recently schooled by hard knocks and my own ignorance, I'm gonna write down a few t'ings I wish I'd known when I started.

    1. Basics: The big mistake on my first build was setting the iron too low to 'protect' those tiny little components. I've since watched lots of old how-to-solder films from trade schools (the newer videos are about soldering microcircuits, pretty useless to us). They point out you need your iron hot enough and big enough to do the typical flow in 2 seconds. Two seconds. Cooler = longer = more time to overheat components. With my inexpensive 40w solder station, solder temp is about 9.5 on the dial and desolder is 10. Works fine. Also, use a tip big enough to contact both the work and the leads; most modern tips are made for work on micro pads and wire. Do flow a tiny microblob of solder between tip and work to facilitate heat transfer -- but then immediately move the solder away from the iron to the work. The work, not the iron, should melt the working solder. And yeah, make sure the wires and leads already hang together by bending, shaping, crimping, or twisting -- solder should anchor things that are already in contact, not fill the void between things that are nearby.

    2. Details: I really like eutectic 63/37 solder. Melts all at once, then sets up at once when you remove heat. Handy for all those parts that wanna wiggle. I like to have both .031 and some .05 or .06 on hand. The fine stuff is great for tacking leads in place, the fatter stuff for filling turrets or eyelets. You can get Kester .031 in 1-oz packs on Amazon if somehow you don't need a 1-pound spool, and Radio Shack has the fatter type in hobby-size reels. Also, get some acid brushes (dead cheap from any solder or amp-building source) and an upright alcohol dispensing bottle -- Amazon has plastic ones, like we guitar types see at the plasma center :D -- and some 100% isopropyl (not drug store rubbing alcohol) to clean joints before and after soldering. Plus, a flux pen (Kester makes one) is superb for big, crusty, or old components. And I found some thicker flux in a blunt-needle syringe that's great for tough or big jobs, like 12 ga wire or Switchcraft plugs.

    3. Turrets v. eyelets: People with a lot more experience than me often strongly prefer one or the other. (Slightly more often turrets?) I've tried both now, and for the early-on builder I'd say:
    • they both work well and they both have advantages
    • turrets are probably easier for attaching multiple leads, and to 'fly' components or arrange at different altitudes
    • turrets are a bit easier to revise *if* you put on the components you might change with no more than a 190-240° wrap, and if you put wires in the center hole with only a short (1/8") straight segment.
    • eyelets work surprisingly well, though, and have one big advantage for the hobbyist: they heat up nice and fast, which makes it way easier to get in, solder, and get out, without swamping your heat sinks (you are using heat sinks, aren't you?)
    • eyelets aren't all that hard to revise, since you can clip the old component, grab the wire stub with small pliers, and pull it as soon as the solder heats; then a solder suction cleaner can totally clean the eyelet from the front while you heat the back -- OTOH sucking solder out of turrets, well, sucks
    • a lead bender (or precise jeweler pliers) can easily form leads to fly components above eyelets too
    • if you're methodical, you can fit a surprising number of leads in an eyelet; there are spots on my PR board with 7 wires in an eyelet, and they weren't that bad. For that matter, it ain't fun doing 7 on a turret either
    • eyelets are actually a bit easier to tack lightly as components get attached -- a very slight tack job can hold things in place during assembly

    4. This brings up another eyelet trick. Crowding all sorts of heat sinks around a turret and then soldering with them there can take a big, hot iron, and just getting the iron into the turret becomes a challenge. Well, you say, at least a turret's not flat, like an eyelet. *But* with an eyelet it's easy to flip the board (on a 3rd-hand-stand, say) with the heat sinks totally out of the way on the front, then solder from the back of the eyelet. Although it's true you can bring backside wires into a turret very nicely and solder them there, good luck attaching 7 things to the front while soldering from the back.

    5. Backside soldering on eyelets is actually a breeze after a little practice to get a feel for how much solder to use. Done right, it makes a gorgeous shiny dome on the front and ... no ugly flux collar. Some people like to do this over a mirror, but I found it hard to light and unnecessary once I got a feel for the X mm of .06 solder that it takes to fill an eyelet and form a dome. Still, practice -- an eyelet with 7 leads fills faster than one with 2. And: there are places (frontside wires that insist on dropping out of place, with only a few, easy heat sinks) where soldering on the front is still easier.

    6. If you want to practice before working on either turrets or eyelets, lots of makers (Doug Hoffman or Watts Audio, for example) will sell you a very inexpensive small board with either turrets or eyelets -- a 5f1 or 5f2a works well. If you don't have extra resistors, wire, and caps from a prior build, you can order a stash very cheaply from any source. It doesn't hurt to order some extras of the actual parts, sizes, colors you'll be using on your build...

    7. Still with me? I find it useful to have at least 3 kinds of heat sink; 4 or 5 of the inexpensive flat silvery spring-loaded kind, a few red-plastic-dipped fat boys, and one or two fine to medium hemostats

    8. A little planning will let you attach heat sinks more easily. Resistors that float 1-2 mm above the board are easier to grab. Try to make sure that components approaching a crowded junction have some lead between body and bend -- this may mean one end has a longer lead than the other. See if some artful offsetting helps you get to both a resistor and its cap -- this is good for heat dissipation too.

    9. Speaking of planning, to put first things last, check and recheck, take a break, and then check again that things are in the right place, are the right things, approach from the correct side (backside wiring needs quadruple checking), and are *all* of the things that go to a turret or eyelet before you fill / finalize. Remember what I said about hard knocks?

    10. Watch those old training films on YouTube and read all the helpful posts about soldering here on TDPRI!
     
    James Knox, xafinity, 6942 and 2 others like this.
  2. Plan9

    Plan9 Tele-Meister

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    Good tips; haven't built an amp, but I'm a fan of the eutectic solder. Any preference on flux type (no clean, RA, RMA, etc); do you use a flux pen?

    Also, what amp kit(s) did you build? Sounds like you're a fan of the eyelet boards.
     
  3. Thin69

    Thin69 Friend of Leo's

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    I'd stay away from RA (rosin activated) as it is much more corrosive than RMA (rosin mildly activated). RMA should be adequate for working inside a chassis. I personally do not like the no clean fluxes.
     
  4. Thin69

    Thin69 Friend of Leo's

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    Nice job King Fan!
     
  5. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    I'll defer to the next post about rosin, but you missed my love note to my flux pen! My vast experience (heh) runs to a 5F2a (built on a Watts turret board) and the PR. Since the Mojo PR came eyelet, I thought I'd try 'em. I like vintage looks and function, but I've been pleasantly surprised, as you mostly hear about turret advantages. That's why I spent more time on eyelets here. I would build with either one in the future depending on several factors.

    Thanks for fielding that. I do like the Kester 44 rosin, but I clean residual flux off everything.

    Thanks for that; I'm no pro, and I'm definitely hoping others will weigh in
     
  6. clintj

    clintj Friend of Leo's

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    Another use for alligator clips/heat sinks: you know those pesky flying leads that never stay still when soldering eyelet boards? Clip them to the board to hold them in place while you work.

    For joining wires, the Western Electric splice is an old proven favorite. Bend and wrap, then flow solder into the wraps to fuse everything together.

    [​IMG]
     
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  7. Plan9

    Plan9 Tele-Meister

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    One more q: what's wrong with no-clean flux?
     
  8. Thin69

    Thin69 Friend of Leo's

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    I spent many years manufacturing high reliability life support electronics. When Freon cleaning processes were phased out we were forced to look at fluxes and develop alternate cleaning processes. No clean fluxes require the activators in the flux to evaporate out of the flux during the soldering process. Unfortunately it was determined that the activators did not always completely evaporate out of the flux residue. Rosin based fluxes yielded better looking solder joints and contamination residues could be completely removed with alternate processes using alcohol solvents followed by a deionized water rinse.

    No clean fluxes are probably fine in a guitar amp but I still have a preference for rosin based fluxes since I have been using them since I learned how to solder in the early 60's.
     
  9. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Clint, I'll be using both your ideas. Excellent. Thin, thanks, great info.
     
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  10. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Meant to post an 'ingredients' pic.

    [​IMG]
     
  11. RLee77

    RLee77 Friend of Leo's

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    I've never used additional flux when soldering generic electronic components; the amount of flux in normal rosin core solder is sufficient. It's messy, creates a lot of nasty fumes, and is more difficult to clean up. If a component lead or terminal or whatever is dirty/tarnished, I'll usually clean it by scraping lightly with an xacto blade or fine sandpaper, then tin it before making the connections. I don't depend on rosin to do major cleaning of leads and surfaces. If doing the back of a pot, shine it up with sandpaper first.

    On the subject of heat sinks... they are rarely needed. No components in a tube amp are that sensitive to normal soldering (normal being about 5 to 10 seconds total soldering time). Heat sinks were required in days of old when germanium transistors were used; a germanium device can easily be nuked by normal soldering if you don't use a good sink. Inside of a tube amp, don't worry about it, just make sure your connection is set and secure before you start soldering, and remove heat promptly after you see good flow on all bits. Also, if doing turret/eyelet board stuff, you already have a big sink in the length of the part lead.

    I do always clean off the flux when I'm done. If you want an easy job of it, use acetone and Q tips, it cuts right through flux, much faster than alcohol. Just be sure you have a lot of ventilation/open windows. Cleaning things up allows you to see if the joint is nice and shiny and solid, in addition to preventing any corrosion afterwards (although corrosion is of little concern with standard rosin core solder).
     
  12. xafinity

    xafinity Friend of Leo's

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    Use caution using alcohol and acetone. Reclose the container everytime you use any. Those are as flammable as gasoline.
    Plus just one drop on the finish of the guitar could ruin your day.
     
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  13. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Alcohol -- the other kind -- should not be mixed with soldering either! :)
     
  14. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    I'm the opposite of an expert, as I always say. I'm sure you're right especially if you solder hot, well, and fast enough. OTOH, the learner may want to use 'em for all those reasons. Also, I'm extra careful to use 'em with delicate little polystyrene caps, which are famously not robust, or where leads are ultra-short, or where lots of small components on fat, short leads come into a big ol' turret or chock-full eyelet. Of course, by the Murphy Clause, those are the situations where they're hard to use.

    Again, I think you're right, I don't use it for regular amp work, but I will match to the job. My flux pen is RMA, my flux paste syringe is no-clean (though I still clean up). They help solder flow fast and smooth over the surface -- lugs come out shiny, not blobby. Yesterday I used a 0.5 (?) mm dot of paste on each of some crimp-on rings -- the solder climbed out and all over the crimp and up along the wire in just a second, yielding a shiny fill that looks totally pro. And the smell -- a sweet, only slightly lead-filled jolt right back to my dad's shop. :)
     
  15. Thin69

    Thin69 Friend of Leo's

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    Acetone is considerably more dangerous. It's flash point is -4F as compared to isopropanol which is 54F.
     
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  16. clintj

    clintj Friend of Leo's

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    The fumes can travel along the floor to an ignition source as they're heavier than air. Additionally, acetone can be absorbed through the skin, and can cause injury to the kidneys and liver. Nasty stuff.
     
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  17. dsutton24

    dsutton24 Doctor of Teleocity Ad Free Member

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    Holy smokes, that's a lot of paraphernalia! My entire soldering equipment collection consists of an iron and a small rock.
     
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  18. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Heh, and I didn't even show my solder station, tips, sponge, sponge sprayer, isopropyl sprayer, shop apron, magnifier, etc. etc. You should see my little basket full of guitar picks, my camping shed, or my box of different ski waxes -- even though I use one kind of those things 95% of the time. Simplicity is a true virtue, but good and various tools are kind of fun too. :)
     
  19. RLee77

    RLee77 Friend of Leo's

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    It's an excellent collection of tips, KingFan, great of you to put that together!
     
  20. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Seriously, I value all these other contributions and group wisdom the most. I got almost all my ideas here!
     
    Last edited: Jun 7, 2016
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