Capacitor Replacement

army_ant7

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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.
 

wuzy

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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.
 

Godhatesusall

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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:eek: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.
 
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
 

army_ant7

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How can I tell if a cap is low ESR?

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... :)
 

wuzy

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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.
 

army_ant7

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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?
 

slo

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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
 

wuzy

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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!
 

Prescott_666

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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.
 

army_ant7

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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?
 

wuzy

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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.

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...
 

4745454b

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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.
 

army_ant7

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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.
 

army_ant7

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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
 

army_ant7

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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?
 

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