Post by candyflipper7 on Jan 17, 2013 15:44:55 GMT -5
Please explain to me how long to actually heat a lug on a pot without frying it to a crisp? I now understand why I have been going to a tech since the 80's now for literally everything I need done on my guitars.... I am determined to finish this project (HHH) without the assistance of my long time tech. But I have managed to have fried a 1 meg tone pot. Is this the meaning of "Rookie Solder Finger"? Help. I could honestly use the expertise of the members in the forums. I will check back in a few days, after I reflect my crazy idea of building a guitar. Besides, I need more time to prepare wire. Thanks _ Flipper
Well, there's the right way, the wrong way, and the Navy way.
Which means, there is no "right way", and there are many wrong ways. The end results are the dictator of what's right, and you need to keep practicing until you get so good that you can solder a correct joint in your sleep. Only at that point can you say "I'm doing it right".
Practice is the name of the game. Here's what I'd do, were I starting out in this business.
First, you need the right tools. If you don't have now, go out and procure a soldering iron between 25 and 40 watts. Too small, and it won't ever get hot enough for this kind of work. Too large, and you risk burning up your parts. Lots of practice will eventually 'guide' you in how to use higher-wattage irons, without damaging anything, but for now, stick to the suggested range.
And don't be using one of them Weller soldering guns, the kind that look a bit like a pistol, and have 100 watts or more of heat - that thing's gauranteed to kill every component you touch with it! Bad juju!
Now, the solder itself. In recent years, do-gooders have found a niggling resistance to their insufferable ignorance in the electronics industry - we simply have better things to do than spend/waste time trying to educate know-it-alls who can't be educated - their IQ was stunted by too much coffee, or too much weed, or something, and all they have left is a big mouth to shoot off in support of demonstrating just how ignorant they are.
Hence, you're not likely to find the correct solder any more, about all you can buy is Lead-free junk that works, but barely. That's sad, but it's the state of affairs, so we'll just have to live with it.
So, find a roll of solder made specifically for electronics projects - do NOT use anything else, or you will be highly saddened at the results. It should be labeled something like 63/37 or close to that ratio. It will probably be labeled as 'lead free' or RoHS, and that's what we want here. (Well, we don't want it, but we're saddled with it, so.....)
What to practice on? Surely not new components, right? Right. Go find some used equipment, the older the better. You want what somebody else is dumping, or has dumped. Computers are usually not good for this, they're all miniaturized, and have nothing we need for soldering practice. Instead, find old TV's, old radios, old amplifiers, etc. You want something with controls on a front panel, switches and pots, so that you can get pretty close to what you'll be doing to your guitar.
Where to find this stuff? Repair shops, retail places that take trade-ins, second-hand stores like Value Village, that kind of thing. Keep an eye posted for free stuff, particularly on craigslist, but your local grocery store's bulletin board also has the occasional ad too. You might post a 'Wanted' ad, in those same places - you never know who's got stuff they were thinking of getting rid of....*
OK, you've got all the requisite stuff on your bench - time to get your hands dirty! ;D
While there are several good websites with tutorials, and more than a few good YouTube videos, let me cut to the chase here - you don't want to heat anything up for too long a time. You want a higher-wattage iron (within that range) so that you are applying the necessary amount of heat for a shorter period of time. Think about it....
If the iron is 700°(F), and you touch it to somethint that's room temperature, it will cool down, well below the melting point of solder. In effect, it has to heat up the area to be soldered, right? So a higher-wattage iron, say 40 watts, will "recover" it's tip temperature quicker, as the heat spreads from the tip into the component. This quick spread of heat into the component is what allows the solder to melt sooner, thus making the connection before you've heated up the whole component/wire/etc. If it takes the iron too long to 'recover' the tip temperature, then that heat will have spread out much further, and that's when we start seeing damage to wire insulation, the internal carbon track of a potentiometer (pot), etc. There are ways to mitigate that kind of damage, but for the most part, "get in and get out" is the best way - apply your heat, melt the solder, and remove the heat... done.
How long to leave the heat on the part, that's a matter of how long it takes the solder to melt. This is why we say "tin the tip first" - you're applying a tiny bit of solder to the tip to help it transfer heat to the component more quickly. Apply that tiny bit, then before it all goes up in smoke, touch the tip to the component/wire/etc. Try it both ways, with and without tinning - you'll see the difference, it's that obvious. Hence you've reinforced rule #2 - tin your tip first.
(What's rule #1, you ask? Geez, if you have to ask, you're not ready for this.... but what the hell, what are friends for, right? Rule #1 - a hot soldering iron looks exactly the same as a cold one. Need I say more? )
OK, that's it in a nutshell. Only Superman learned how to solder with his X-ray vision, the rest of us had to practice, practice, practice. That's gonna include you too, unless you're wearing a cape under your shirt......
* Obligatory SAFETY warning.... in any old equipment, with or without tubes, you need to be sure that not only is the power off/disconnected, but that any high-voltage capacitors have been discharged. If you have questions about this, ask them here in this thread and we'll address those concerns with another diatribe lesson in safety.
Rule #1: All Lives Are Final. Make sure that the life you have just been issued is appropriate for your needs, before departing the womb.
Rule #2: In case you don't like the life you have, see Rule #1.
There shouldn't be any problem soldering a pot lug, if your iron is suitable. What do you use?
EDIT - what sumgai says - he da man! (posted while i wrote)
Steps I use (others feel free to comment/disagree etc):
Heat the iron thoroughly make sure it is clean (eg wipe it on some wire wool) wet it with some new solder 'tin' the lug, by putting the hot tip on it, and feeding in some new solder to melt on the lug so it flows wetly - 3 seconds Tin the wire end to connect to it place them together with good contact, and melt the solder on each, feeding in a bit more - 3 seconds Pull off iron, holding everything rigidly until it sets - a few seconds
If you find you need much longer than those times, then the iron is not hot enough/clean enough/in contact enough. That is when heat can travel further and damage something.
A more common problem with pots is soldering to the back - it needs a powerful iron, and clean/abrade a small patch on the pot to solder to. then the same procedure - maybe an extra second or two max but not more.
For lugs, wires and components, a 20-25W iron is good. I used to try to use a 25W for pot backs, but never any success. Now I have a neat little chinese iron, 20W with a fine tip, and a handy red button that boosts it to 130W! - for up to 30 seconds (or else you take responsibility for the consequences). Its really good for those pot backs, I can get a neat little wet solder blob quickly, then pull off before everything melts. I'm not sure what power is more normal for pot backs - not 130W!.
Another factor is the new lead free solder - and I'm still using the old lead/tin stuff, which melts much more easily. But Ive noticed that unsoldering things on new RoHS compliant gear is much harder than it used to be, so building with this stuff would also be affected.
Most pots need to be filed or sanded to bright metal, the "tinned" This is crucial. They often have a coating of machining oil, plating or at least some oxidisation. This simple step alone tends to make it all easy. Creat a nice bright tinned connection, and teh same on the wire and tehn just melt the two together. And, always preparpe the parts outisde of the guitar, if not the whole wiring if possible...do not attempt to just poke around in a tight cavity with a hot iron. Switch pots can be hazzardous as the switching element inside is plastic, so avoid excessive heat and file those for grounds...I'll tend to use the side of teh pot muself or the edge as easier to file...
as with most things, prep is the key!
Mr D.I.Y. Sustainer ;-) [/IMG]New Project...'jazz strat' ... Seagull project and mini PA amplification