Removing !@$% Capacitors!

[napierzaza]

I recently acquired a G5 iMac that was having issues. I checked inside and happily realized that the capacitors were shot in the unit, which I could easily fix myself. I had already done this to an older eMac that I was also broken down with no issues whatsoever. I even harvested the caps from elsewhere and it cost me nothing.

So, I ordered the replacements and I got them in the mail today. So tonight I giddily tried to remove the caps and ... no dice. They're stuck, I even put my iron up to 400 degrees C and I couldn't even get the caps to budge at all. I even tried ripping the caps from the board and realized that I couldn't even stick the caps on sideways onto the pads that are left.

So it looks like it's using some kind of leadless solder. Does anyone have a suggestion to remove stuff like this? I never encountered such a large, through-hole part that was so impossible to remove. I can't even get it to budge one bit.

[stryd_one]

hard to say, not knowing what the solder is... If for some bizarro reason you can't melt the solder... Cut the leads as close to the cap/as far from the board as possible, and solder your new cap onto the stumps. It's ugly, but it works...

[Goblinz]

If that's not possible then there's the uglier solution of using some jumper wires!

[seppoman]

in some commercial units, the caps are glued to the pcb before soldering. you could try to melt one leg's joint and then apply brute force sideways in the direction of the other leg and so try to tilt the cap in a way that the heated leg comes up a little. then same thing in the other direction and alternate until the cap is lifted.

[napierzaza]

Actually I was trying to tilt the off the board by heating one pin then the other. I busted a cap (hehe) doing this because the legs just gave way. I then used pliers on the remaining pin and applied heat and pulled. I still couldn't do it.

I tried soldering to the stump, IT DOESN'T WORK! My beads just don't stick to the pads! Their like the anti-solder pads or something. Do I have to somehow clean the board first? It doesn't appear dirty, or to have any sort of coating, but I don't know how it's rebuffing my efforts like this. How are they servicing this stuff?

[stryd_one]

Using the right flux would help for sure, but we don't know what the right flux is.... The thing I suggested was not to solder to the pads, it was to leave the existing legs soldered to the pads, and solder to the legs. If the legs are resisting your solder too, sand them back a bit. It's all metal under there :)

[ilmenator]

How are they servicing this stuff?

Well, they are not... they just put in a new mainboard, even for a busted USB connector. This world is crazy. (And sorry for not being of any help in your matter.)

[stryd_one]

Yer, parts are cheaper than labor. Unless you go to a third world country and have someone refurbish them in batches, and that's what happens to the dead ones they pull out, in our countries. Isn't it nice to know that you contributed to slave labour today? (Don't feel guilty, it's not like you have a choice. Just complain loudly)

[TheAncientOne]

I've hit this one quite a few times. The answer is usually a hidden layer ground plane. You simply can't get enough heat into the board to melt the solder, the thick copper for the motherboard's power gridding conducts it all away. The problem is not getting ahot enough iron, but of getting one with enough wattage. I've had 2 irons at once on some boards. Good news is that I've only ever had one not start working again after about 15 cap change jobs. Abit slot 1 boards were notorious: they'd fallen foul of the famous capacitor electrolyte scandal.http://www.dashdist.com/1u2u/company/capacitor.html

Some fancy electrolytics actually have some kind of weird formed aluminium pins, which are pre-tinned. Getting a flux to stick to that bare metal, (and which isn't so corrosive it ruins your boards), is going to be a problem. These are usually only large 'snap fit' ones used in big power units though.

[Goblinz]

wonder if one of those gas powered irons would be any better???

[napierzaza]

Actually I am taking the job of a slave laborer!

I already pulled off about 5 caps and often enough I am not left with enough leg to attach to it. So it's nto a solution for the ones I already did, or the ones in the future that it will happen to me.

It might be the central ground plane, as you mention, EXCEPT that I can't even hardly get the solder around the pin liquid enough. It's still tacky after touch a 400Celcius iron.

I think I go out and buy some flux :-\

[Goblinz]

Actually I am taking the job of a slave laborer!

I already pulled off about 5 caps and often enough I am not left with enough leg to attach to it. So it's nto a solution for the ones I already did, or the ones in the future that it will happen to me.

It might be the central ground plane, as you mention, EXCEPT that I can't even hardly get the solder around the pin liquid enough. It's still tacky after touch a 400Celcius iron.

I think I go out and buy some flux :-\

Could still be the ground plane dessipating the heat

[cimo]

Use a dremel and make a new hole through the board.

[nILS]

...and *poof* goes the plating.

[cimo]

at 30000 rpm you can afford the risk, if he didn t rip it off with all this pulling and prying...

[TheAncientOne]

Do not drill - most motherboards are multi layer, and you might drill right though buried layers and either short or break them.

You need a 40 watt iron, minimum, preferably a bigger one. If you haver a friend to help you can use two irons at once.

Check what type of solder was in use on the board, if lead free you need to be working with lead free.

Add a small pool of new solder around the pin, this will hold heat and allow better flow/contact.

Move one pin a little, then the other. When pulling cut off pins, see if you can get some ceramic tweezers, they don't steal heat from the pin.

Temperature is not the issue here, the actual amount of heat that you can apply is.

One trick to un-block holes you cannot suck the solder out of with a desolder tool, is to find a thin propelling pencil lead and slip it through the hot solder. It can be broken out when the solder cools,

Hope this helps a bit

[napierzaza]

Thanks for the suggestions.

I have to work with non-lead if it is non-lead? I thought they would mix and make the non-lead solder more pliable.

I will check how many watts my iron has. But I think it should be a lot. If not I am borrowing a friend's gas powered one.

[SLP]

One trick to un-block holes you cannot suck the solder out of with a desolder tool, is to find a thin propelling pencil lead and slip it through the hot solder. It can be broken out when the solder cools,

something that is similar to TheProf's proposal is described here:

http://www.ulrichradig.de/home/index.php/tipps_tricks/tipp1

Try to get a hollow needle, you can get them in a drugstore. Try to get one which inner diameter matches your Cap-lead. heat the solder a bit and try to slip the needle between the PCB and the lead. Solder usually doesn't connect to the needle as it's made from noble metal. This way you should be able to remove it if the solder is hard to melt.

But I doubt that this method will work in your case...

[napierzaza]

Gas powered iron is A++, but I won't be using the holes on the board, little ugly!

[/tilted/]

... perhaps you need to get a mac-compatible soldering iron? perhaps the iron you have only works with PCs...  :P

[napierzaza]

Woooooooooooooooooooooooo

Thanks again guys

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[Goblinz]

Yey!

I mean, urghhh, it's a mac.  :P

Did the gas powered soldering iron do the trick then?

[napierzaza]

Whatever man, Macs are awesome.

Yes, it worked, though the possibility of using the old holes was still nil. I have a bunch of caps soldered on at 45 degree angles. But hey, it works.