Apart from the soldering iron, you either need a solder "sucker" or, soldering wick (I prefer the former).
Using the soldering iron (one with a small tip), hold it at an angle and heat up the soldering joint (on the other side of the PCB).
At the same time, hold the solder sucker ready in your other hand.
As soon as the solder starts to melt, quickly remove the soldering iron and place the solder sucker next to (or on top of) the soldering point to "suck up" the melted solder.

The same approach can be followed if there is solder in the "top" part (where the capacitor is).
If you have too much trouble, then you can try to clip off the capacitor and then "open/clean up" the soldering joints with the soldering iron and solder sucker.

This will sometimes require a couple of tries.

jesolo wrote:

Apart from the soldering iron, you either need a solder "sucker" or, soldering wick (I prefer the former). Using the soldering i […]
Show full quote

Apart from the soldering iron, you either need a solder "sucker" or, soldering wick (I prefer the former).
Using the soldering iron (one with a small tip), hold it at an angle and heat up the soldering joint (on the other side of the PCB).
At the same time, hold the solder sucker ready in your other hand.
As soon as the solder starts to melt, quickly remove the soldering iron and place the solder sucker next to (or in top of) the soldering point to "suck up" the melted solder.

The same approach can be followed if there is solder in the "top" part (where the capacitor is).
If you have too much trouble, then you can try to clip off the capacitor and then "open/clean up" the soldering joints with the soldering iron and solder sucker.

This will sometimes require a couple of tries.

On the back of the PCB on the pins there's seems not to be any solder but only the usual old metal pin and it seems to be soldered "inside" not entirely on the back as usual. But I need to buy that tool you're saying and try it.

Yes, you have to remove the old solder as soon as you melt it. Otherwise, it cools off and you're back again where you started 🤣 .

But, don't worry. I'm also fairly new to soldering and de-soldering and, after a couple of retries, discovered this worked the best for me.
There are some videos on Youtube that provides some tutorials on how to solder and desolder, but I'm sure that the more experienced users here on Vogons can also provide you with some sound advice.

In my experience, adding some fresh solder to the joints usually makes the components a lot easier to pull out. After removal, you can clean the pads with solder wick (if there's still solder covering the holes you can use the needle trick).

Some motherboards use lead-free solder. That can be a pain in the ass to remove. Try to mix in some leaded solder.

I sometimes use a stainless steel pick to clean molten solder from the through hole. Faster than a solder sucker.

Could You give us the model number of the board? even a photo, it helps considerably.

People have different ways of doing it, with practice you'll find what works for you.

Soldering irons struggle to deliver heat to exactly the spot where it's needed. Assuming you don't have a very expensive soldering station, one thing to keep in mind is that when the tip makes contact with the joint, it cools off quickly, then has to wait for the heater in the iron to heat it back up again. This is the challenge with heavier joints.
You want the tip on it's own to be able to transmit enough heat into the joint to melt the solder before the tip cools off. Tips with more thermal mass are more effective.

There's a temptation to use a small conical tip, but these do a poor job of conducting heat at that tip. Many people (including me) prefer to use a chisel tip. I have several sizes but use the 2.4mm and 3.2mm chisels on most motherboard caps. I only use smaller sizes if the larger tips don't feel comfortable. I also have a 5.0mm but it feels too bulky for most situations. The general principle is that larger tips have more thermal mass, which helps them to get more heat into a joint.
The quality and variety of tips varies depending what iron you have, of course, but a ~2-3mm range chisel is the most useful tip IMO.

Add 63/37 or 60/40 lead based solder to the joint. This does a couple things - one the flux in the new solder will clean the surface of the joint so it's more receptive to heat. Secondly it increases the contact area and helps conduct more heat into the joint.
On that first point, you can also add flux separately.

Solder suckers and solder braid are controversial. Some people hate or love either of these. It's partly personal preference and the knack that people have learned with their preferred tools, but I think quality of the tools can also be part of it. I can't do anything but the most rudimentary cleanup with braid, but some people swear that they can clear joints with it. I've even seen it on video, but it could have been witchcraft. 😀
I have a large Edsyn Soldapullt that I've been happy with. I bought it basically because it was the most reputed simple solder sucker I knew of, expensive for a solder sucker ($30) but far short of the cost and complication of a powered vacuum sucker.
Most people seem to buy smaller unbranded solder suckers and I'm not sure if they work as well. I would assume the reduced size means they don't generate as much suction, or at least they're obviously not moving as much total air.
At least with the Soldapullt, the tip is designed to withstand heat reasonably well. You can put the sucker right over the joint while the iron is still on it. I haven't had a great experience trying to suck lead-free concrete but leaded solder comes up pretty well.

All that said, I don't think a sucker is that necessary for capacitors. Personally with capacitors I like to melt one joint and gently rock the capacitor up on that side, then alternate to the other side, back and forth until it's free. Solder suckers can also work but with 2 legged devices I think it's usually easier to just rock it out.
For replacement, you might want to clean the holes with a solder sucker (adding solder can actually help with this also), or just use the needle trick (which I think tends to be easier on the harder joints).

shamino wrote:

People have different ways of doing it, with practice you'll find what works for you. […]
Show full quote

People have different ways of doing it, with practice you'll find what works for you.

Soldering irons struggle to deliver heat to exactly the spot where it's needed. Assuming you don't have a very expensive soldering station, one thing to keep in mind is that when the tip makes contact with the joint, it cools off quickly, then has to wait for the heater in the iron to heat it back up again. This is the challenge with heavier joints.
You want the tip on it's own to be able to transmit enough heat into the joint to melt the solder before the tip cools off. Tips with more thermal mass are more effective.

There's a temptation to use a small conical tip, but these do a poor job of conducting heat at that tip. Many people (including me) prefer to use a chisel tip. I have several sizes but use the 2.4mm and 3.2mm chisels on most motherboard caps. I only use smaller sizes if the larger tips don't feel comfortable. I also have a 5.0mm but it feels too bulky for most situations. The general principle is that larger tips have more thermal mass, which helps them to get more heat into a joint.
The quality and variety of tips varies depending what iron you have, of course, but a ~2-3mm range chisel is the most useful tip IMO.

Add 63/37 or 60/40 lead based solder to the joint. This does a couple things - one the flux in the new solder will clean the surface of the joint so it's more receptive to heat. Secondly it increases the contact area and helps conduct more heat into the joint.
On that first point, you can also add flux separately.

Solder suckers and solder braid are controversial. Some people hate or love either of these. It's partly personal preference and the knack that people have learned with their preferred tools, but I think quality of the tools can also be part of it. I can't do anything but the most rudimentary cleanup with braid, but some people swear that they can clear joints with it. I've even seen it on video, but it could have been witchcraft. 😀
I have a large Edsyn Soldapullt that I've been happy with. I bought it basically because it was the most reputed simple solder sucker I knew of, expensive for a solder sucker ($30) but far short of the cost and complication of a powered vacuum sucker.
Most people seem to buy smaller unbranded solder suckers and I'm not sure if they work as well. I would assume the reduced size means they don't generate as much suction, or at least they're obviously not moving as much total air.
At least with the Soldapullt, the tip is designed to withstand heat reasonably well. You can put the sucker right over the joint while the iron is still on it. I haven't had a great experience trying to suck lead-free concrete but leaded solder comes up pretty well.

All that said, I don't think a sucker is that necessary for capacitors. Personally with capacitors I like to melt one joint and gently rock the capacitor up on that side, then alternate to the other side, back and forth until it's free. Solder suckers can also work but with 2 legged devices I think it's usually easier to just rock it out.
For replacement, you might want to clean the holes with a solder sucker (adding solder can actually help with this also), or just use the needle trick (which I think tends to be easier on the harder joints).

That's some solid advice. I do however prefer bevel tips for desoldering (and actually most soldering jobs too), chisel tips have their uses though. But guess that's a question of personal preference 😀

Completely agreeing with you about desoldering braids. They're basically useless if you don't have a station designed for desoldering, with the necessary power. My 80W station won't do the trick unless the conditions are more or less optimal. Choosing a thinner braid than you'd think you need, and adding some flux into the equation helps, but in the end, a good solder pump with a heat resistant teflon nozzle beats the braid in almost any situation. I can see some use for really thin braids when desoldering SM components, but if you're into that, you should really invest in a hot air rework station instead. Nowadays there are cheap ones with adequate performance. Gotta love China 😁

I know I've mentioned here before, but can't hurt to do it again; I usually preheat heavier boards to 130-150 deg C with a hot air gun before desoldering, keeping track of the temperature with an IR thermometer. Heat from the bottom side. Those boards and components are usually wave soldered, and are made to withstand some heat. Just be careful with plastic details and electrolytic caps you want to keep.

kaputnik wrote:

I do however prefer bevel tips for desoldering (and actually most soldering jobs too), chisel tips have their uses though. But guess that's a question of personal preference 😀

I should try using a bevel sometime. I have at least 1 but I don't think I've ever actually used it. At the time I was ordering a bunch of tips I had seen bevels suggested for SMT stuff, but it never occurred to me to try it on anything else.