Couldn't Desolder a Capacitor...

Jesse69

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I was testing my new Radioshack Digital Solderer - http://www.radioshack.com/product/index.jsp?productId=3132686#

- and I put it up all the way to 842F for the tip but it couldn't desolder a capacitor end off a bad capacitor on my sound card. I put the tip to the solder and it would hardly melt away and through the board so I'd be able to remove the capacitor end. Now is it my desoldering technique that's bad or I gotta a no good Digital Solderer?

According to this web page the solder should have melted easily http://www.rfcafe.com/references/electrical/solder.htm

- Or else do they use ultra high melting point solders on Williams PCBs?

And don't electrolytic capacitors go bad with age so you gotta replace them? They sorta dry out or so?
 
You need to ADD solder when you want to de-solder. The new solder helps to heat up the old solder joint you are trying to remove.
 
So I guess the trick is to add low melting point solder and this will mix with the high temp solder and make it easier to remove?

Gee, desoldering IC chips must be a pain?
 
The old solder oxidizes and that raises the melting point of the solder. Adding a little fresh solder acts as a conductor to get more heat to the solder on the board and flows fresh lead lowering the melting point of the old solder.

Solder can also be affected by environmental hazards as well. Water, battery alkalai, capacitor fluids, beer, cola, etc. can damage the solder and wil require a little patience and some practice. Be very careful not to overheat the solder pad or you may burn the trace or lift the solder pad off the board. Neither is a good thing.

Patience is the key. Wait for the soldering iron to fully heat up. Those RS POS irons can take 15 minutes to fully warm up. They are also not thermostatically controlled so it is very easy to overhead pads and traces which will break the adhesion to the circuit board. This can put cracks in the traces that will need to be repaired later.

ken
 
also rs desoldering braid sucks.. get some good stuff from mcm or some other company.. trust me, youll be able to tell a huge difference.


ALso make sure that your tip is clean and TINNED.. you should also tin your tip after you are done soldering. Itll help that tip last longer...
 
You might want to find a garbage PCB to practice on before you start on something that you want to keep. As far as soldering goes, practice makes perfect. It's not hard.
 
desoldering braid=desoldering wick..


lay it over what you want to desolder, lay the iron on top, the solder melts and is drawn up into the wick, then you remove the wick and iron at the same time..



makes desoldering most things a breeze.. much better then the sucker method imho...
 
Vacuum pump desoldering irons FTW!

Also, look at the cap you are trying to desolder. If there's a big ground plane on top of the board you'll have a hard time heating the pin to desolder it cleanly.
 
Vacuum pump desoldering irons FTW!

Also, look at the cap you are trying to desolder. If there's a big ground plane on top of the board you'll have a hard time heating the pin to desolder it cleanly.

One trick - if you are having trouble desoldering something that you don't want (for instance, a cap that you are replacing), AND you can get to the leads, try clipping the component off first, then de-solder the end of the lead that's left in the board. Without the component sucking up heat, it's sometimes much easier to remove the bits that are left.
 
Vacuum pump desoldering irons FTW!

Also, look at the cap you are trying to desolder. If there's a big ground plane on top of the board you'll have a hard time heating the pin to desolder it cleanly.


+1. If you are not trying to save the cap, then just cut the lead as close to the body of the cap. You will have less mass to heat. If you are removing it to test it, you only need to lift one side and leave the one on the ground plane alone. For large ground planes, I crack out the "heavy artillery" - my trusty old soldering gun - heats quickly and will melt any solder joint. Great for removing those pesky Pacman / Galaxian audio heatsinks.

If the solder is oxidized (looks VERY dull or has some crust on it), brushing the oxidation off with a brass brush or fiberglass pen can help. Then add some solder to your iron tip to "wet" it before you touch the solder joint.

Bill
 
Desoldering things off professionally produced boards such as arcade boards is next to impossible without a good solder sucker. I use the Goot, which is a japanese brand.

p1.jpg
 
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