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Capacitor Replacement

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June 3, 2009 7:02:50 PM

Hello, can anyone provide tips and tricks for replacing old caps with new ones? Any tips and tricks at all. Feel free to post. Hehehe...

How do I know if a capacitor is suitable to replace another capacitor? Do they have to be exactly the same? The only specs I know there are are voltage, uF (microFarads), size/dimensions, and heat tolerance...

The capacitors I'm gonna change are the ones near the CPU; they're five of them lined up.

More about : capacitor replacement

a b V Motherboard
June 3, 2009 7:17:37 PM

i wouldn't recommend it, you will probably just damage the motherboard (though if it is already not working or you don't care, then why not try it)
June 3, 2009 10:59:29 PM

Low ESR, same voltage, capacitance can be slightly higher if you intend to use the motherboard for extreme clocks benchmarking.
Keep in mind motherboards are multi-layered so you have to make sure you don't create a dry joint in between layers (not visible). Use flux to prevent it happening.

I had to replace about 15 caps on my EPoX 8RDA+ back in the days due to the leaking cap era (clones from China). The board gained more stable vcore under high voltage.

[EDITED]Make sure the diameter of the cylindrical capacitors are the same. So that it'll fit snugly on the PCB. Height can be taller or shorter, doesn't matter.
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a c 98 V Motherboard
June 3, 2009 11:21:41 PM

This doesn't look like the site when I visited it several years ago, but it sounds like the right one. Give it a read, it should have some info for you.

http://www.badcaps.net/
June 3, 2009 11:22:29 PM

In order to change the capacitors of ANY given electrocal circuit,one must be certain that ALL capacitors are empty of electric charge,or you're risking damage to hardware.So,first of all ground(manually to be sure) all the large(in size) capacitors you can find.


In order for 2 capacitors to be the same they must have the same capacitance(ex 5 uF) AND be able to withstand the same voltages(carefull on the last one)

One more thing to look after is what kind of capacitors you will take.There are some(called electrolytic) which can ONLY be placed in a specific way:The + part of the capacitor must go to a higher voltage and the - to a lower voltage,or you will have a very shiny explosion next time you try to boot ur pc.However,other types of capacitors can be placed both ways,so be sure to get the right ones.

Then there are the technical part,which i cant really explain it to you cuz there are a million parameters to think:o verall inductance on the PCB,speed and any electronic automation circuits etc etc etc....

Your best bet is to find exactly the type of capacitor used by the manufacturer.Unplug a capacitor and write here any specs printed on,and then maybe i can help you more.
a b V Motherboard
June 3, 2009 11:41:23 PM

Don't forget to fit the replacement capacitor the right way around. :ouch: 
June 4, 2009 11:40:39 AM

Thank you... All of you guys. Hehehe... What's ESR btw?
a b V Motherboard
June 4, 2009 11:11:38 PM

soft clamp the motherboard onto something as to hold it and not damage it, and use either a heat gun or sharp tip soldering iron to soften the solder and pull it out from the opposite side (up, or where everything is on etc) without bending the board too much

to get them back in same deal but adjust the wires to there going to go into the holes, heat up the opposite side and push them in, and if needed perhaps a touch of solder etc

easy
a b V Motherboard
June 4, 2009 11:13:33 PM

Do I sense some insane OCing just around the corner? :D 
June 5, 2009 9:42:56 AM

How can I tell if a cap is low ESR?

Quote:
soft clamp the motherboard onto something as to hold it and not damage it, and use either a heat gun or sharp tip soldering iron to soften the solder and pull it out from the opposite side (up, or where everything is on etc) without bending the board too much

to get them back in same deal but adjust the wires to there going to go into the holes, heat up the opposite side and push them in, and if needed perhaps a touch of solder etc

easy


That method won't create a cold joint? I don't have to take out all the solder at all?


If anyone else has any suggestions, feel free to post... :) 
June 5, 2009 10:18:14 AM

When I did it I used the 'steel needle through the hole' method after removing the old caps to retain some solder between the layers before inserting new caps in for soldering.
June 5, 2009 10:25:57 AM

Quote:
When I did it I used the 'steel needle through the hole' method after removing the old caps to retain some solder between the layers before inserting new caps in for soldering.


Did you apply any additional solder?

When I take out the old caps, do I leave the soldering iron tip on the spot until the capacitor comes off?
June 5, 2009 10:48:02 AM

Soldering capacitors to the motherboard is a difficult process and requires a good extend of precision and soldering skill. I wouldnt do it unless there is no way arrond it or i have money to throw away on a new mobo in case of damage
June 5, 2009 10:58:19 AM

army_ant7 said:
Quote:
When I did it I used the 'steel needle through the hole' method after removing the old caps to retain some solder between the layers before inserting new caps in for soldering.


Did you apply any additional solder?

When I take out the old caps, do I leave the soldering iron tip on the spot until the capacitor comes off?


Just a tiny bit, the legs of the old cap removed some during the desoldering process.

About what slo said, I guess the basic skill is to not leave the soldering iron in contact with the joint for too long (less than 4s for 18/25W iron, I use a temp. controlled one) and do not use excessive force to pull the old cap out when desoldering. Let the solder melt entirely by applying enough heat before pulling.

I've been soldering stuff since being 6yrs old so I guess those stuff comes naturally to me. It's still just a hobby tho of course.

The hotair rework station I purchase last month has made so many small jobs far more easier, I love it!
June 5, 2009 12:05:16 PM

I don't know how long the leads are on the old capacitors. If they are too short, you can't do this, but If the leads are long enough, I would cut them as close to the old capacitors as possible, and solder the leads of the new capacitors to the leads of the old capacitors.

It won't look as nice, but it's a lot easier, and you are a lot less likely to ruin the motherboard. If you try to do this, and the leads turn out to be too short to splice the leads of the new capacitors to them, you can still try to remove them, and solder through the board.
June 6, 2009 2:47:43 AM

Quote:
I've been soldering stuff since being 6yrs old so I guess those stuff comes naturally to me. It's still just a hobby tho of course.


Jesus! Really? Wow! How? Isn't it kinda dangerous for a young child holding a soldering iron?

Btw, how do I determine if a cap is low-ESR?
June 6, 2009 3:56:28 AM

You can read the datasheet of the capacitors you're buying (please don't let us tell you to use Google again...) to get every bit of detail of it.
If I remember correctly I used mostly Panasonic FM series which are made in Japan and have some of the best spec. around.

Quote:
Jesus! Really? Wow! How? Isn't it kinda dangerous for a young child holding a soldering iron?

*shrugs* I think even a child know its hot and you don't go and touch it...
a c 98 V Motherboard
June 6, 2009 6:20:12 AM

Some children know this better then others. With my parents permission, I've been carrying a pocket knife of some sort on my since I've been 10. (might have been 9, don't really remember) I wasn't the kind of kid who fights, or would use it in a bad way. My parents wouldn't let my younger brother get one until he turned 18. Some kids handle things better then others.
June 7, 2009 11:30:54 AM

LOL! Hehehe... Does anyone want to talk about the heat resistance of a cap? Any tips about it?

BTW, I can't seem to find the manufacturer of my caps. I bought them by piece.
June 14, 2009 6:17:11 PM

OMG! I started desoldering my capacitors ok? So... The first capacitor removal went ok, but the next 4 (I need to replace 5.) I was able to remove the negative cap leads with ease, but the positive was a different story. I tried taking them out but the tin just won't melt so I kept the soldering iron on the spots and tugged a little on the capacitors. The thing is the capacitor lead broke of on that part from the lead still embedded in the motherboard. So I thought, "That isn't a problem. I'll just try using the heat a pin through the hole trick." And so I did, but the lead just won't come out. So I have 1 hole ready for a replacement and 4 holes with only their negative holes ready for replacement. How do I take those leads out?

What should I do?! Anyone, please help! Wahahaha... T_T
June 14, 2009 10:34:38 PM

Take a photo of it and post it here. I'll see what can be done.
June 15, 2009 12:32:00 PM

Ok, it might take a while though. I don't have camera on hand though; I'll have to borrow one. I just have to note that I'm lacking also in materials. I only have a 100W 200+V soldering iron, a manual solder sucker(the one with a spring you push down on), a steel needle, maybe a dentist pick that was prescribed in www.badcaps.net, an anti static packaging plastic which I place on top of my legs in an Indian sit position (cross legs) where I work on. Hehehe... This may hilarious for some, and it really is, but I'm trying to find others.

Can anyone tell me what I'm missing, and where I can buy them?
a b V Motherboard
June 15, 2009 5:33:30 PM

100W??? I believe that's too much for this kind of work?
June 15, 2009 8:25:01 PM

What should it be? It's the only one I saw? What's wrong if I use 100W; is there any danger?
June 15, 2009 8:39:46 PM

Here, it didn't take so long after all:



My whole motherboard. You may notice that it looks old.




Here is one capacitor I soldered in already with 4 empyt slots in the same row. They have there positive(not white) sides filled with a capacitor lead that broke off. :( 




This is the back side...




This is the underside of the capacitor slots in the 2nd image. It's kinda blurry though.


Please can someone help me? Anything I can do to take the leads out?
a b V Motherboard
June 15, 2009 8:59:06 PM

Quote:
What should it be? It's the only one I saw? What's wrong if I use 100W; is there any danger?

100W is WAY too much for this kind of work (Unless you have a adjustable one?). For sensitive electronics like this usually a 20-45W are usually used. You can use a 100W as long as you don't hold it on a joint too long. 50W+ are used to solder heavy gauge wires, battery terminals,etc.
June 15, 2009 9:05:42 PM

You mean it can actually damage my motherboard? It's kinda weird... No matter how long I leave the iron on the joint the solder doesn't want to melt.

Guys look at the post with the pictures above. I really need help with that.
June 15, 2009 9:23:55 PM

Add a bit of extra solder that contains lead to lower those RoHS solder's melting temperature. Once you have a nice big glob of melted solder you can then precede to remove the old cap's leg. Remove excess solder afterward, I prefer using solder wick over suckers.

And 100W is definitely way too much, which most of those irons have a pretty massive tip to for that purpose. I would estimate mine to be around 24W @320C, it's temp. controlled. The tip I used is pin-like, I sharpened it, so I can use it to solder SMD components. Vmodding a HD2900XT was an absolute pain w/o a proper soldering tip. :ouch: 

Oh and learn how to use autofocus properly on your camera. :p  With pocket cams you have to have a large focal length as they don't do macro. Just crop the focused area (displayed as 1:1) if you want take a pic of something detailed.
I can hardly see the soldered spots in those pics.
June 15, 2009 9:30:59 PM

So I shouldn't use silver tin for this operation? What's RoHS? Where should apply the solder, the component side or the soldering side? I should just apply the solder then heat it up again? Is your soldering iron connected to a machine?

Sorry for all the questions. Hehehe... Can you answer all through quick reply? TY!
June 15, 2009 9:39:24 PM

army_ant7 said:
So I shouldn't use silver tin for this operation? What's RoHS? Where should apply the solder, the component side or the soldering side? I should just apply the solder then heat it up again? Is your soldering iron connected to a machine?

Sorry for all the questions. Hehehe... Can you answer all through quick reply? TY!


RoHS is basically solder with no lead, they met the RoHS environmental requirement. They have much higher melting point and are a PITA to work with for soldering hobbyists.

Read this to get a better understanding of differences between solder contents (and find out what's yours). I normally use the standard 60/40 (Sn/Pb).

Quote:
Where should apply the solder, the component side or the soldering side?

To get things melting I touch a bit of extra solder onto the iron tip which then flows onto the soldering point that needs melting, and form as a bigger blob of solder.

When soldering new components and applying fresh solder, you're meant to heat the component's leg up and let the solder melt onto the leg to be soldered and not onto the iron tip itself. I personally found it easier to apply fresh solder in between the leg to be soldered and the iron tip. Just don't leave solder on the iron tip too long, otherwise flux will be burnt off. Flux is needed to avoid dry joint.

Quote:
Is your soldering iron connected to a machine?

Mine is, as it's temp. controlled. Non-temp. controlled ones with a static wattage don't have one tho.
June 15, 2009 9:53:32 PM

How about my other questions? Thanks.
June 17, 2009 6:45:27 AM

So I can use my 100W just don't leave it on too long? How do the legs come off by the way? Will I use a pin?
a c 98 V Motherboard
June 17, 2009 10:09:07 AM

I believe your supposed to use a 35W iron. These are 1) hard to find and 2) will take forever to use. A 45W is better. (I used a 45W when I did this. It worked, but I only replaced one, and had several more die within a month of me using it.) The "legs" of the cap don't come off. After you solder it, use some snips to cut it short.
June 17, 2009 10:15:44 AM

No man. I was talking about something else. Here's the story. I accidentally broke off the legs of the capacitor. Now the legs are still stuck in the hole. I want to take them out, but I've been trying by applying heat and pushing a metal pin through, but it won't move out. Is it wrong when I de-soldered the negative terminal 1st?

Again anyone? Any tips to help me out?
a b V Motherboard
June 17, 2009 4:20:48 PM

May be pull it with a bit of force while heating? (might need some one elses help)
June 17, 2009 9:30:32 PM

Snipping off the stub from the top (non-soldering) side then pulling the remain from the bottom (soldering) side is one option.
The hole is a tight fit to the leg so you have to do the snipping very cleanly to avoid getting stuck.
June 18, 2009 12:17:45 AM

I can't snip any thing anymore. When I accidentally broke the legs with ignorance :( , it was left only until a part that is kinda inside the hole. No part sticking out. I also made a fairly clean cut on the solder side. Sorry. :( (
June 21, 2009 1:04:26 PM

Hello? Is anyone still there? Hehehe... My problem really must be that stupid. :p 

BTW, does anyone know what those 2 or 3 holes in the positive semi-circle(half-moon) of the place where you put capacitors? They're filled with solder but no components seem to be in them. What are they for? They get in the way when I try to mix solder. Is it ok to have a solder bridge between the capacitor hole and those holes?
June 23, 2009 6:41:07 AM

army_ant7 said:
I can't snip any thing anymore. When I accidentally broke the legs with ignorance :( , it was left only until a part that is kinda inside the hole. No part sticking out. I also made a fairly clean cut on the solder side. Sorry. :( (

Add more solder to the area to get the hole molten and use a pin to push whatever that's stuck in the hole out is what I'd do.
June 23, 2009 6:51:02 AM

Quote:
Is it ok to have a solder bridge between the capacitor hole and those holes?
Don't bridge them...
Use a solder wick/braid to clean up the mess after you've cleaned the holes out.
June 23, 2009 1:48:16 PM

Quote:
Add more solder to the area to get the hole molten and use a pin to push whatever that's stuck in the hole out is what I'd do. Don't bridge them...
Use a solder wick/braid to clean up the mess after you've cleaned the holes out.
wuzy

What hole do you push out with the pin, the hole that I have a cap leg stuck in or the 2-3 lead holes that are just filled with solder?

So, you really do suggest that I use a soldering wick? Does it have the ability to drain out the rest of the solder like a solder sucker when I take out a component? I hope I could find one here...

What are those annoying holes actually for?

Thanks man for coming back.
February 17, 2010 1:20:00 PM

I replaced 9 swollen capacitors on my motherboard and now the only thing I have power to is the fan and lights on the front. It was my first attempt and I was going to replace the motherboard anyway because the computer was having problems. After checking out everything else I figured it was worth a try. I found that adding solder to the legs and gently pushing on them while wiggling the capacitor worked real well. I also marked the ones I was going to remove first because there are some places with no caps.
a c 156 V Motherboard
February 18, 2010 10:49:33 AM

wuzy said:

The hotair rework station I purchase last month has made so many small jobs far more easier, I love it!

Curious. What did you get?

BTW, do you realize that you can use the braid from shielded wire for solder removal? Just strip the shield out and put a couple of drops of liquid flux on it.
Anonymous
a b V Motherboard
August 2, 2010 2:07:36 PM

army_ant7 said:
OMG! I started desoldering my capacitors ok? So... The first capacitor removal went ok, but the next 4 (I need to replace 5.) I was able to remove the negative cap leads with ease, but the positive was a different story. I tried taking them out but the tin just won't melt so I kept the soldering iron on the spots and tugged a little on the capacitors. The thing is the capacitor lead broke of on that part from the lead still embedded in the motherboard. So I thought, "That isn't a problem. I'll just try using the heat a pin through the hole trick." And so I did, but the lead just won't come out. So I have 1 hole ready for a replacement and 4 holes with only their negative holes ready for replacement. How do I take those leads out?

What should I do?! Anyone, please help! Wahahaha... T_T


The problem is that the motherboard is obsorbing too much of the heat from the iron (the copper leads), thus you are not getting the proper heat from the soldering gun. I have done many boards and had the same problem. Havent found a good resolution for this, usually I crank it up to 900, use a lot of flux and hope it heats the actual solder. I have never damaged a board from heat yet but I have come close. I almost melted the contact once so you have to be really careful. I like the idea of using a heat gun, I am going to try it on my next attempt.
August 2, 2010 3:12:17 PM

HAHA, i think its just time to buy a new motherboard.
April 5, 2014 8:26:31 PM

You can save big bucks if just replace the Caps, I have a $1000 system and replaced my own caps for 2 bucks. By all means replace them, not the motherboard if it's worth fixin. I have pictures of what I did let me know if you need them. I got a bunch of 1000uF 16v 105*C just for this issue.
!