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Anyone else having problems with CTS pots?

petrus61

petrus61

Dec 18, 2011
11,762
14,931
Hudson Valley, New York
#1
Maybe I'm an idiot and I am somewhat new to soldering, but I've just burned out my third CTS pot in a week. I wired an Alpha and a no name brand every time the same way to replace them (tone) and haven't had a problem with them at all. It seems every CTS pot I put in, I somehow cook. I'm willing to chalk it up to inexperience, but why are they burning out so much quicker then the flimsy no name pots that I keep replacing them with?
 
#2
petrus61 said:
Maybe I'm an idiot and I am somewhat new to soldering, but I've just burned out my third CTS pot in a week. I wired an Alpha and a no name brand every time the same way to replace them (tone) and haven't had a problem with them at all. It seems every CTS pot I put in, I somehow cook. I'm willing to chalk it up to inexperience, but why are they burning out so much quicker then the flimsy no name pots that I keep replacing them with?
Click to expand...

What soldering iron do you have, and how long are you leaving it on the pot. I have never had any problems with CTS pots.
 
#3
Quality pots like CTS and Bourns have a thinner coating than the cheapies, and thus require less time at lower heat to reach proper soldering temperature. Your typical Alphas, Nobles, and unknowns tend to have their coating gobbed on and it seems like it takes forever to heat those things. On the flipside, an Alessandro or PEC will hit temp in a heartbeat.

Questions I have for you are: what type of solder are you using; what wattage/type of iron; is the tip properly cleaned and tinned before each use? Any of these being 'wrong' can cause problems.

Rob
:bassist:
 
#4
I'm using two irons: a 40watt Weller and a 30watt cheapie. I am tinning the iron and have had success doing a few CTS in the past. Using 60/40 rosin core. I'm using the same duration on both the Alpha and CTS. That's what's messing me up is that it seems the opposite as described...the CTS are taking much longer then the Alpha to melt the solder when applied. I feel like the longer time on the CTS is cooking its innards, while the cheapo's are heating just right. I'd welcome any tips because the feel/taper of these Alpha's I am not used to at all.
 
#7
OK, everything you're doing sounds right, so my guess- and only that, as I'm not there with you, nor can I see your irons unless you post a pic- is that your tips may be oxidized/dirty. If they are, the heat gets trapped and forces you to leave the iron on the work longer; however, prolonged exposure to 'not as hot' will still cook a pot, as opposed to a few seconds of 'hot hot hot.' If you're sure you're tips are clean as well as everything else? Then the only suggestion I have left for you is to take a safety razor/blade and scrape off the coating on the CTS pots where you intend to solder- it'll make adhesion much quicker and easier. That and make sure you have a dab of solder on the pot, and the wire(s) tinned so all you have to do is quickly heat the pot and place the connection.

Rob
:bassist:
 
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#8
giorob815 said:
OK, everything you're doing sounds right, so my guess- and only that, as I'm not there with you, nor can I see your irons unless you post a pic- is that your tips may be oxidized/dirty. If they are, the heat gets trapped and forces you to leave the iron on the work longer; however, prolonged exposure to 'not as hot' will still cook a pot, as opposed to a few seconds of 'hot hot hot.' If you're sure you're tips are clean as well as everything else? Then the only suggestion I have left for you is to take a safety razor/blade and scrape off the coating on the CTS pots where you intend to solder- it'll make adhesion much quicker and easier. That and make sure you have a dab of solder on the pot, and the wire(s) tinned so all you have to do is quickly heat the pot and place the connection.

Rob
:bassist:
Click to expand...

This might be it. Maybe I'm forgetting to dab the iron in the sponge more often and it's oxidizing the tip. I was convinced it was crap irons or just a new alloy or something on the pots. I'll grab a new tip tomorrow and see what happens.
 
#9
giorob815 said:
OK, everything you're doing sounds right, so my guess- and only that, as I'm not there with you, nor can I see your irons unless you post a pic- is that your tips may be oxidized/dirty. If they are, the heat gets trapped and forces you to leave the iron on the work longer; however, prolonged exposure to 'not as hot' will still cook a pot, as opposed to a few seconds of 'hot hot hot.' If you're sure you're tips are clean as well as everything else? Then the only suggestion I have left for you is to take a safety razor/blade and scrape off the coating on the CTS pots where you intend to solder- it'll make adhesion much quicker and easier. That and make sure you have a dab of solder on the pot, and the wire(s) tinned so all you have to do is quickly heat the pot and place the connection.

Rob
:bassist:
Click to expand...

This is very good advice.
 
#10
Don't sponge. It lowers the tip temp. too much, then you need to wait for it to heat back up; and then you sponge, it lowers, etc.; ultimately leading to premature tip- and iron- death. If you have a Radio Shack or equivalent near you, get a tip cleaner or Invalid Link Removed. It can be a bit expensive for what you get, but it's worth it.

Rob
:bassist:

Edit: The thing w/ sponging is that the iron temp isn't lowering naturally, so forcing the tip to cool when it's still trying to be hot is what causes the wear and stress.
 
#11
giorob815 said:
Don't sponge. It lowers the tip temp. too much, then you need to wait for it to heat back up; and then you sponge, it lowers, etc.; ultimately leading to premature tip- and iron- death. If you have a Radio Shack or equivalent near you, get a tip cleaner or Invalid Link Removed. It can be a bit expensive for what you get, but it's worth it.

Rob
:bassist:

Edit: The thing w/ sponging is that the iron temp isn't lowering naturally, so forcing the tip to cool when it's still trying to be hot is what causes the wear and stress.
Click to expand...

I wouldn't spend any money on that - I've been using a damp paper napkin for years, and it works really well... Fold it up so that it's thick enough, and move to a different fold when it gets too dirty... You should be able to get several solder jobs out of one napkin - I just put in inside the case with my soldering gun and iron, roll of solder, de-soldering braid, etc...


- georgestrings
 
#12
There is no reason to scrape the coating off the pot. Tin your wire, place the iron on top of the wire pressed down on the pot, and touch the wire with one dab of solder. It should flow onto the pot if you do it right.
 
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#13
Hopkins said:
There is no reason to scrape the coating off the pot. Tin your wire, place the iron on top of the wire pressed down on the pot, and touch the wire with one dab of solder. It should flow onto the pot if you do it right.
Click to expand...

I haven't been scraping the CTS pots because I thought they didn't need it. The Alphas on the other hand did. I've been using a moist paper towel but apparently that's not it because I haven't been dabbing too much. Would a little sandpaper to the tip help? I've been using a silver solder too, I that makes any difference.
 
#14
petrus61 said:
I haven't been scraping the CTS pots because I thought they didn't need it. The Alphas on the other hand did. I've been using a moist paper towel but apparently that's not it because I haven't been dabbing too much. Would a little sandpaper to the tip help? I've been using a silver solder too, I that makes any difference.
Click to expand...


I have always just used lead free rosin core. I don't have experience with silver solder.

What tip are you using? Are you using a fine point tip or a chisel tip? Chisel tips give you more heat transfer to the surface.
 
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#17
I regularly solder using CTS pots, being a guitar tech at a music store. I have yet to cook a CTS or Alpha. Here's a few points I've picked up, and though I'm sure some here will argue it's not necessary, I follow these steps and have no problems.

1) Use the 40 watt, not the 30.
2) Get a tip tinner from Radio Shack, and the brass-plated Chore Boy looking thing to keep the tip clean, also available at Radio Shack. It works better than anything else and doesn't drain heat. DON'T try to cheap out and use an actual Chore Boy. The price of those two items together is cheaper than full retail on a CTS pot.
3) Rough up the back of the pot with a file, and put some flux on the spot, then heat it and apply solder.
4) I use a screwdriver tip, but really you just need anything but the super fine pointy tips. An overly large chisel tip may tax your iron's ability to keep it hot enough to solder.
5) Clean and tin the tip for EACH JOINT. Sounds like a lot, but once you're in the habit it becomes second nature and insures better soldering.

YMMV, but I have yet to burn up a pot since I started following those steps given to me by a much, much more experienced electronics tinkerer.
 
#18
This was from a Strat that our guitarist asked me if I could repair.

uQAOz7z.jpg


Ho much solder do you need on the back of one pot? Pretty bad soldering all round.
 
#19
^ I've had a lot of customers bring in work that looked like that. There's always a back story involving a friend who said they could fix or improve it, and now it's noisy or non-functional. Neatness counts!
 
#20
Wow delta, that is about as bad as I have seen. Not just the globs of solder on the back of the pots, but those lugs couldn't have a worse connection. Look how grey the look. Not to mention that they burned all the insulation off of the wires.
 

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