I've got a board from a Mackie powered sub I'm repairing for a friend, and the 15-year old PCB is putting up a fight. I'm trying to desolder two big electrolytics, and I just can't seem to get the joints hot enough with a Radioshack 45W solder sucker (the one with the iron and bulb on top) to be able to pull the solder out. I had one that worked perfectly, but the other three aren't cooperating.
I haven't tried using braid yet, but if you guys think I'll have better luck with that, I'm all for it. I tried heating the joints up with my Hakko iron, but even at 800deg, it seemed like it didn't want to melt.
Kind of at a loss here.
Thanks
I haven't tried using braid yet, but if you guys think I'll have better luck with that, I'm all for it. I tried heating the joints up with my Hakko iron, but even at 800deg, it seemed like it didn't want to melt.
Kind of at a loss here.
Thanks
Actually, you don't need to remove the solder to remove the component. Large caps sometimes have crooked tab-like connectors instead of wires and these actually add mechanical strenght to the connection. Sometimes they are hard to remove, and perhaps that's why your cap is still in place after you removed the solder
My suggestion would be to use your iron and melt the solder on the pad one leg at a time and gently try to pry off the component as the leg loosens. Be careful not to force the junction, you might peel off the solder pad. Do the same for the other leg, even if it's just 1mm at a time, until the component is completely loose. Patience is important because if you damage the board traces, it's a mess to repair!
Afterwards, use the solder braid, or your sucker to remove the remaining solder and you'll be all set to put the new cap. Make sure your replacment has the same (or somewhat similar) physical size and leg spacing because it's often hard to find a cap that has the same specs as the one you're replacing.
Good luck and happy hobbying!
Robert
My suggestion would be to use your iron and melt the solder on the pad one leg at a time and gently try to pry off the component as the leg loosens. Be careful not to force the junction, you might peel off the solder pad. Do the same for the other leg, even if it's just 1mm at a time, until the component is completely loose. Patience is important because if you damage the board traces, it's a mess to repair!
Afterwards, use the solder braid, or your sucker to remove the remaining solder and you'll be all set to put the new cap. Make sure your replacment has the same (or somewhat similar) physical size and leg spacing because it's often hard to find a cap that has the same specs as the one you're replacing.
Good luck and happy hobbying!
Robert
Robert's comments above are pretty accurate in my experience. My technique is similar:
First get yourself a real solder sucker. It's a tool that's worthwhile having. It doesn't have to be super fancy and expensive. But a spring loaded sucker is worth having. Depending on the size of the tip of the sucker, you can somehow get a little more suction by cutting a small notch in the tip to allow it to fit around the component pin and soldering iron a little better.
Heat the solder joint until the solder flows freely. For a double-sided PCB remember that you need the solder to flow on both sides so it'll require a few seconds of heating time. If the solder won't flow, wet the joint with some new solder or apply flux.
Once the joint is heated through, approach with the solder sucker (soldering iron is still heating the joint). Suck the solder away with one or two pumps with the sucker. Remove soldering iron and allow the component pin to cool.
At this point there's usually a little solder left in the hole - especially if the PCB is through-plated. By gentle prying/pushing the component lead with a small flat blade screwdriver, it's usually possible to break the remaining solder so you can remove the component.
If above isn't enough, reapply solder to the connections and use Robert's method of heating one joint, pry component a little bit, heat the other joint, pry the other way. Repeat until component is free. Some times if I fail to get all the solder out on the first try, I'll resolder the component completely with new solder and try the removal process from the start. If the second attempt fails, I'll resort to the heat&wiggle process.
Remeber that the PCB tracks are glued to the PCB and too much heat will destroy the glue. Don't heat any solder joint for more than 10 seconds before allowing it to cool. 700 degrees (380 C) should be plenty provided that the tip of the soldering iron has enough contact area to get the joint heated up.
~Tom
First get yourself a real solder sucker. It's a tool that's worthwhile having. It doesn't have to be super fancy and expensive. But a spring loaded sucker is worth having. Depending on the size of the tip of the sucker, you can somehow get a little more suction by cutting a small notch in the tip to allow it to fit around the component pin and soldering iron a little better.
Heat the solder joint until the solder flows freely. For a double-sided PCB remember that you need the solder to flow on both sides so it'll require a few seconds of heating time. If the solder won't flow, wet the joint with some new solder or apply flux.
Once the joint is heated through, approach with the solder sucker (soldering iron is still heating the joint). Suck the solder away with one or two pumps with the sucker. Remove soldering iron and allow the component pin to cool.
At this point there's usually a little solder left in the hole - especially if the PCB is through-plated. By gentle prying/pushing the component lead with a small flat blade screwdriver, it's usually possible to break the remaining solder so you can remove the component.
If above isn't enough, reapply solder to the connections and use Robert's method of heating one joint, pry component a little bit, heat the other joint, pry the other way. Repeat until component is free. Some times if I fail to get all the solder out on the first try, I'll resolder the component completely with new solder and try the removal process from the start. If the second attempt fails, I'll resort to the heat&wiggle process.
Remeber that the PCB tracks are glued to the PCB and too much heat will destroy the glue. Don't heat any solder joint for more than 10 seconds before allowing it to cool. 700 degrees (380 C) should be plenty provided that the tip of the soldering iron has enough contact area to get the joint heated up.
~Tom
1) Flux the solder joints!
2) Heat soldering iron and de-soldering iron up
3) Try to loosen any adhesive holding the cap on from the top side
4) Deflate sucking bulb, place de-soldering iron over lead. Some of the larger components (including most main reservoir caps) require a larger amount of heat transfer to get the solder joint melted thoroughly. I usually put the tip of the soldering iron on the pad simultaneous with the de-soldering iron to help melt it.
5) Once it melts, wiggle the de-soldering iron + cap lead in a circular motion a few times then allow the bulb to inflate.
If you come close to sucking it clean, but not quite. Sometimes you can gently wiggle the lead side to side and it will come loose. If you didn't even come close to sucking it clean, it can sometimes be helpful to add solder back to the joint before attempting to de-solder it again.
2) Heat soldering iron and de-soldering iron up
3) Try to loosen any adhesive holding the cap on from the top side
4) Deflate sucking bulb, place de-soldering iron over lead. Some of the larger components (including most main reservoir caps) require a larger amount of heat transfer to get the solder joint melted thoroughly. I usually put the tip of the soldering iron on the pad simultaneous with the de-soldering iron to help melt it.
5) Once it melts, wiggle the de-soldering iron + cap lead in a circular motion a few times then allow the bulb to inflate.
If you come close to sucking it clean, but not quite. Sometimes you can gently wiggle the lead side to side and it will come loose. If you didn't even come close to sucking it clean, it can sometimes be helpful to add solder back to the joint before attempting to de-solder it again.
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First, contaminate ROHS solder with old fashioned leaded rosin core 60/40.
That will make it a million times (and a hundered degrees) easier to suck or
wick the holes clean without scorching the board or causing the pad to lift.
Lead will penetrate into a ROHS blocked hole and soften it, don't you worry...
Use a heat gun to warm the ground plane around the hole if one refuses to
get hot enough with an iron alone. Use aluminum foil to mask off any plastic
parts or electrolytic caps that might get burned by the heatgun.
If you don't care about the bad part, you can cut the body away from the
leads (but leave some sticking above the board) to pull them one by one...
This will also give you access to apply lead and flux on both sides of the hole...
That will make it a million times (and a hundered degrees) easier to suck or
wick the holes clean without scorching the board or causing the pad to lift.
Lead will penetrate into a ROHS blocked hole and soften it, don't you worry...
Use a heat gun to warm the ground plane around the hole if one refuses to
get hot enough with an iron alone. Use aluminum foil to mask off any plastic
parts or electrolytic caps that might get burned by the heatgun.
If you don't care about the bad part, you can cut the body away from the
leads (but leave some sticking above the board) to pull them one by one...
This will also give you access to apply lead and flux on both sides of the hole...
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You want one of these:
Edsyn DS017
Anything less is a waste of money. And many things that cost much more don't perform much better.
I find braid is most useful for cleaning up, like when replacing surface-mount things. Braid varies in effectiveness, too. Maybe the flux deteriorates with age, or off-brands just aren't as good.
Edsyn DS017
Anything less is a waste of money. And many things that cost much more don't perform much better.
I find braid is most useful for cleaning up, like when replacing surface-mount things. Braid varies in effectiveness, too. Maybe the flux deteriorates with age, or off-brands just aren't as good.
Adding more solder helps, as this adds fresh flux and the extra solder aids the heat transfer from the iron.
I also keep a cheap unregulated temperature iron for difficult to remove parts. I find that it is particularly useful for removing parts on large groundplanes, or multi layer PCBs (as on a computer motherboard for instance).
If these capacitors have bent over tags, you may need to remove the solder with braid, then heat and straighten the tag using an iron and a small pointed tool. Then add more solder and pull the leads out, then clean up with the solder sucker
I also keep a cheap unregulated temperature iron for difficult to remove parts. I find that it is particularly useful for removing parts on large groundplanes, or multi layer PCBs (as on a computer motherboard for instance).
If these capacitors have bent over tags, you may need to remove the solder with braid, then heat and straighten the tag using an iron and a small pointed tool. Then add more solder and pull the leads out, then clean up with the solder sucker
I'm with Robert here. Heat one leg of the cap until the solder melts, using a regular iron. Rock the cap body away from that leg however far the slack will let you. Then heat the other leg and push the cap sideways to rock that leg out as far as it will let you. Each step will get you more slack. Back and forth a couple times and your cap is free.
THEN worry about cleaning the hole.
Even with all my fancy desoldering stations, I don't always rely on sucking all the solder away to get large parts out
THEN worry about cleaning the hole.
Even with all my fancy desoldering stations, I don't always rely on sucking all the solder away to get large parts out
I'm with Dangus- anything smaller than the full size "Soldapullit" he recommends is useless. I have about 4 of the shorter units from them, RS and others, and they're all inadequate. We have commercial desoldering stations at work and the DS-017 is just as effective, albeit slower to use. I'm not a big fan of wick, having burned myself on it too many times, but for some things it can't be beat. Definitely add flux and solder and be sure your iron tip has a lot of thermal mass, i.e., is big enough for the job.
CH
CH
This is pretty much what I had to do, came out perfectly.
Does anyone have experience with a desoldering gun, like a Hakko 808? I hear good things about Pace stations, but also that they can be a little maintenance-intensive, and I'm not sure I want to make that kind of investment unless I know I'm going to be using it a lot (which I probably won't).
I have the RS WP 45 desoldering tool, it's hollow tip won't transfer heat fast enough to do anything bigger than a TO-92 transistor or DIP IC. For big old electrolytics, that suck a ton of heat into the can, I use a 120W Sears pistol gun. I'm cheap,to suck solder I use scrap wire of about the size I am trying to remove (16 or 14 ga on big electrolytics) dipped in Oatey #5 Solder paste (zinc cloride) from the hardware store, to suck the solder off. I cut the shiny bit of wire off with cutters, strip some more, dip in flux, and keeps sucking until solder is gone. This is cheaper than desoldering braid and much more available in a non-electronic town like this. For heavy work like FP cans using a solder sucker tool risks melting the plastic tip off. The Oatey flux is said by others to be an acid flux, so I wash the area down with a damp paper towel when I am finished. As a previous person said, on a FP type or Aerovox can with ground tabs you will have to suck the solder off and also twist the can tab while hot to get out of the socket or chassis. A lot of times the can tab breaks. When I put the can back on, usually a WP25 iron with chisel tip has enough heat for the wires(not pointed), the Sears gun is put away. Sometimes I have to use the big gun on the can tabs to chassis. I have a WP80 iron which should be big enough, but it doesn't really get hot enough to melt SN-PB solder at all hardly.
Pretty much what the others have already said. Your first mistake is the use of the wrong tool and your second, the wrong technique.
Big power caps have big power and ground traces, or even worse in this case, planes, and they're all excellent heatsinks. A weak iron will just slowly heat up the cap and the board, not good for either of them.
You'll almost never get a cap out by cleaning the joint first. They tend to be a tight fit and with the heatsink properties, as the joint clears and you lose thermal transfer from the lack of solder/contact area, it cools what's left and leaves too much in the joint to enable the removal of it. If you try breaking it, you very likely will. You'll have an impossible time reflowing the joint then as well without additional solder.
First step is to reflow the joint and add fresh, leaded solder. If it's lead free solder in the joint it'll turn cloudy with the mix, but that's fine, it will lower the melting point anyway.
I tend to use braid to clean it as much as possible, then wash it with fresh leaded solder, and maybe repeat once or twice so that it flows easily, then lace the solder to it for good heat transfer while I wiggle it out one leg at a time. Keep adding solder to ensure good thermal transfer, as what's there will get sucked through the via by the leads as they pull out.
If you try using braid to clean the joint fully with cap in place it's just adding another heatsink so you really need a hot iron.
I Wouldn't bother with the guns, they're pieces of junk, never reliably heat the tip, and you can get a pencil or butane iron for the same price that's hot enough for the job.
Of course when you use the wiggle technique, since it can start off very slow, it often doesn't hurt to trim the leads a little before you start, and bend them straight.
For smaller caps with a tight lead pitch let the surface tension of the solder bridge the leads, heat both simultaneously while alternating via to via to ensure good heat transfer directly and wiggle it right out in under three seconds with minimal strain.
Extra tip, when doing one leg at a time, hold the cap tilted while you remove the iron and let the joint solidify, don't worry if your finger burns, this is normal. Otherwise you may be going nowhere fast as the cap will resettle in the second it takes for it to solidify.
Big power caps have big power and ground traces, or even worse in this case, planes, and they're all excellent heatsinks. A weak iron will just slowly heat up the cap and the board, not good for either of them.
You'll almost never get a cap out by cleaning the joint first. They tend to be a tight fit and with the heatsink properties, as the joint clears and you lose thermal transfer from the lack of solder/contact area, it cools what's left and leaves too much in the joint to enable the removal of it. If you try breaking it, you very likely will. You'll have an impossible time reflowing the joint then as well without additional solder.
First step is to reflow the joint and add fresh, leaded solder. If it's lead free solder in the joint it'll turn cloudy with the mix, but that's fine, it will lower the melting point anyway.
I tend to use braid to clean it as much as possible, then wash it with fresh leaded solder, and maybe repeat once or twice so that it flows easily, then lace the solder to it for good heat transfer while I wiggle it out one leg at a time. Keep adding solder to ensure good thermal transfer, as what's there will get sucked through the via by the leads as they pull out.
If you try using braid to clean the joint fully with cap in place it's just adding another heatsink so you really need a hot iron.
I Wouldn't bother with the guns, they're pieces of junk, never reliably heat the tip, and you can get a pencil or butane iron for the same price that's hot enough for the job.
Of course when you use the wiggle technique, since it can start off very slow, it often doesn't hurt to trim the leads a little before you start, and bend them straight.
For smaller caps with a tight lead pitch let the surface tension of the solder bridge the leads, heat both simultaneously while alternating via to via to ensure good heat transfer directly and wiggle it right out in under three seconds with minimal strain.
Extra tip, when doing one leg at a time, hold the cap tilted while you remove the iron and let the joint solidify, don't worry if your finger burns, this is normal. Otherwise you may be going nowhere fast as the cap will resettle in the second it takes for it to solidify.
In a pinch, and from the run what you brung department, I just strip some insulation off cheap stranded copper wire, 18 gauge or so. Twist the strands together tight, form a nice u-hook at the end, dip into solder paste, put some solder flux paste on the soldered joint, and place the fluxed wire right up against the soldered joint and apply a hot solder iron tip onto the copper stranded wire. It should fill the wire with the solder in no time. I make a 3" double ended one, leaving the insulation on in the middle so it's easy to hold without feeling heat on your fingers. Works great! Cleans the joint really nice and helps preserve the solder pads on removal of the component. Tilting the soldering iron down to put more surface area of the heated iron helps too. a 45 degree angle works well.
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