Official Luthiers Forum!

I taken a short detour to the dark side and I'm trying to solder the ground to the back of the pots and am having a heck of time. So I'm hoping I can be enlightend on these couple of questions.
1) Why solder to the back of the pots anyway, why not just use the ground lug of the pot? All the info I've seen on wiring has you using both the back and ground lug.
2) How do you ever get enough heat onto the back of the pot to get the solder to stick?
Thanks,
Jim

_________________
Jim Watts
http://jameswattsguitars.com

Jim, A good ground is essential to quality signal. In my industry the ground wires are about twice the size of the power wires. Soldering is about getting proper heat transfer in the shortest time so you need an iron that is properly sized and properly prepared (tinning the tip properly before use). A good rosin core solder will help with getting a good solder joint. Practice on an old pot before you do the new one. Heat the work not the solder.

_________________
Wisdom is justified by her children

Good advice from Mark- you definitely need a heavy soldering iron for this job.
That said, I've come across some newer pots that are 'almost' impossible to solder- even with sanding, flux, etc it is a challenge. So that old 'practice' pot may be easier to work with....
Soldering to the pot case is more of a 'guitar tradition' than electronic necessity, I think, though it does avoid the solder lug problem if the locking nut loosens up. Sometimes there's room to have an extra nut on the shaft, just to hold the solder lug secure.

Cheers
John

Soldering on the back can sometimes be a challenge. What I do is before I install any of the pots into the guitar I tin all of the lugs and a spot on the back of the pot. To do this you put some flux on each lug and on the back, it is important to use flux or you will never get it to stick to the back. Then touch your soldering iron to the surface that you wish to solder, make sure the solder iron is very hot, add a bit of solder lift off the soldering iron and let it cool. I find without the flux I couldn't get the solder to stick to itself. You need to do this before any type of wiring.
The reason you soldier the back and the lug is because I believe there is a separation, or a lack of a good connection between the back and the lug. It is all done for noise and safety. To help avoid an electrical shock. I find it more of a challenge getting the ground attached to the bridge on one of the Tone pro's.

I clean up whatever I'm soldering (if need be) with a quick sanding, then put a bunch of flux on, and I usually put the solder directly onto the iron tip. Iron is usually turned all the way up. Dab it in and hold until the joint is made. Things started working a lot better when I stopped relying on 'flux core' solder and started brushing on real flux.

(If doing SMT or something then a lower heat can be necessary, of course, and working with high heat means you need to go faster. But, if you work at the proper speed then a higher heat results in less heat input to the parts)

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Guys, thanks for the replies. I've now got some real flux and will go give it a whril.

_________________
Jim Watts
http://jameswattsguitars.com

It's not absolutely necesary to use the back of the pot, as long as all the ground points that would have been attached to a pot are brought together and connected to the ground lug of the jack with wires. This is called a "star ground" and works just as good.
Personally I find it very convenient to just use the back of the pot, as if you have more than a couple of pots you end up with a lot of wires to solder to ground and it gets to be quite cumbersome. I never have a problem getting the solder to stick to the back of the pot. I use a wide chisel point soldering iron tip and a digital soldering iron set to 650 F and tin all my wires and components. I never have the iron on the work more than a second or two. Heat the back of the pot and touch the solder to the pot, NOT the iron tip, and let the solder melt and flow onto the back of the pot. When the pot is hot enough for the solder to "stick", it'll flow onto the pot all by itself. If your ironis hot enough, it won't take more than a second or two, and the component won't get hot enough to be damaged. Let the components cool before test working them.

_________________
Old growth, shmold growth!

I know this is a little late, but not unlike you, I've made the trip to the dark side (because I'm starting to play Bass).

After studying John Atchley's site (guitarnuts.com) and Star Grounding (as mentioned above), I took a stab at rewiring my PBass. Didn't work because I overheated the pots when I was trying to remove the solder. I just ended up rewiring the whole thing with brand new pots and a new pup. However, I followed Phil D'Eon's Marcus Miller Bass style of grounding and just soldered the ground wires together (not on a washer). Long story short, it works, and after shielding, it doesn't pickup as much of my friend's cell phone hum as it did before. Pretty neat. . .

Star grounding can be simply achieved by a method I've seen in Bartolini preamps. They use wires soldered to locking washers on each pot along ground. Very effective when used along with shielding paint in a control cavity. I prefer to solder to the back of pots though, along with using a shielding paint in the control cavity, and it works well for me.

_________________
http://www.aecustomguitars.com

Good advice up top.

1. Clean your work. Small wire brush.....then acetone on a Q-tip.
2. I like to use rubber bands on a needle nose pliers as a clamp to help hold the wire in place prior to soldering.
3. Heat the pot and the wire together for a few seconds and add the solder to the other side of the wire.
4. Use thin rosin core solder.
5. As soon as the solder melts take the heat away - it's done.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic