To solder on Alpha potentiometer surface

[Ichabod]

Hello, I have a weird issue with an Alpha pot.
I always used CTS pots, but a friend of mine asked to me to save some money for a cheap guitar, so I bought an Alpha pot.
This: https://www.banzaimusic.com/alpha-gtr-kn-us-500k-log.html

I noticed it is hard to solder wires on its surface.
I soldered on it a solid core, it was strong but the soldering looked like a ball. So I heat up again the iron and try to melt better the tin, but the tin rolled up on itself and detached from the surface. It's like the surface was "tinproof".

I'm not new with iron solder, on gutiar and PCB, but this never happen to me with other pots.

I don't want to mess up this potentiometer, now the soldering is solid, looks shine even if a bit rounded than I usually used to make.

What's exactly the problem with this potentiometer?

Thank you.

 

[GuitarStv]

Take a pocketknife or something and scratch the back of the pot up a bit. Sometimes there are oils left on them from the manufacturing process that prevent good adherence of solder. Scratching down a bit seems to let your solder grip better.

 

[GuitarDoc]

I routinely "scratch" the surface of pot backs before soldering to them. Like GS said, manufacturing leaves oils, etc on the surface that can't just be wiped off. Also, it helps to use soldering flux paste or liquid, even if you are using rosin core solder.

 

[DCikes88]

^This.
It is always good practice to scuff up the top of a potentiometer a bit for the solder to adhere better thus giving a better and long-lasting connection.
Not all pots are created equal certainly, but this is a good thing to do, especially on cheaper pots which are more prone to having oily residue from manufacturing.

 

[Securb]

Like others have said, I hit mine with a bit of sand paper before soldering them it gives a better bond.

 

[Wattage]

I'll even wipe them with some denatured alcohol first then scuff them, no need to grind the oil into the surface, but yeah a quick scuffing makes the difference

 

[Mincer]

Yes, the alcohol trick works well. I used to get so frustrated when my beautiful shiny solder joint would just slide off.

 

[Ichabod]

For my second attempt I tried to scratch a bit the surface with a sandpaper, but it didn't help too much, maybe that spot was kind of "compromised".
Next time I need to use Alpha pot if I wipe it with alcohol and scratch it a bit and clean it again it'll be better.

Anyway, it's never been a problem with CTS, nor with even cheaper pots. It was just this Alpha. Probably the solution are all the things you suggested, and thanks to all. But did you never try an Alpha pot in particular?

 

[ErikH]

I use Alpha pots a lot actually. Been having quality issues with CTS that shouldn’t happen. Never had a problem with an Alpha. I put one in one of my Strats last night. Scuffed the back up good and no problem soldering. Used a small wire brush from my soldering tool kit.

 

[GuitarStv]

I use alpha pots all the time and have never had problems, but I've always scuffed the back (the guy who showed me how to solder told me to do it).

 

[ErikH]

And don't forget to scuff up the lugs a bit too. For the same reasons.

I have Alpha pots in my SG Jr kit guitar that were put in 11 years ago. Not one issue ever. I've been going through CTS pots more than I should be. They get noisy, they cut out, stuff that should not happen. I don't know what's going on or if I'm getting bad batches but I can't have that.

 

[GuitarDoc]

I've used probably over 100 Alpha pots and never had the severity of this issue with them. I've also used many CTS and Bournes pots as well as others and never noticed any consistent issues like this with any one brand...but then I always scratch the backs and use flux paste. I use flux on every contact and when I'm tinning the stranded wires as well. I just don't want there to be ANY potential issue with any of my solder joints and have to go through the process of finding out where the problem is and then resoldering it. Just do it right the first time and have peace of mind.

I'm wondering if there may be other factors involved, like maybe your soldering iron doesn't have enough power/watts to keep the tip hot enough soldering to all of the metal involved with wires to backs of pots. The only time I had that kind of a problem was many, many years ago when I was using an underpowered iron.

 

[Ichabod]

Probably I have to scratch the surface.
The soldering iron should be enough good for this stuff, I used it of some guitars wiring, with other pot. This is the first Alpha pot and is the first issue like that.

Thanks!