When Capacitors Spring Leaks
Electrolyte has leaked from the capacitors next to an AGP connector.
Interior ESR is basically defined by the electrolyte's conductibility. Hence, electrolytes used in low ESR capacitors have to be especially conductive. To increase the conductibility of the electrolyte, you add additives. One of these additives is water. And because of this water allotment, the number of free ions and therefore the electronic conductibility increases.
However, unclean water can attack the aluminum body of the capacitor, which causes corrosion. The corrosion process creates gases inside the capacitor, increasing the interior pressure - you can see a failing capacitor turn lumpy. The top of the capacitor has a predetermined breaking point, so the gas can escape in case pressure gets too high. Yet, from time to time top will not rip open and the capacitor will explode with a bang. The same thing happens in case of extreme overvoltage. The electrolyte still present can pollute the motherboard and cause short circuits, which might even set a computer on fire. Motherboard breakdowns caused a number of problems between 1999 and 2005 for some manufacturers. Capacitors with improper or low-grade electrolytes were used, causing numerous failures and a drastic decrease in motherboard life.
But not only unclean electrolytes can damage capacitors. Like any other liquid, the electrolyte can simply change its physical condition and evaporate. This happens not only when a system is in operation, but can also occur while the system is shut down or the motherboard is stored somewhere. We all know that components such as RAM and CPUs benefit from proper cooling. Cooling also increases the life expectancy of capacitors, since the probability of evaporation correlates with ambient temperature. An unwritten law says that a 10°C drop in temperature doubles the life expectancy of a capacitor.
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Recognizing of broken capacitors is not so simple in some cases.Reply
Sometimes (very often in my case) have capacitor its nominal capacity but it has high serial current. When you connect DC voltage of capacitor nominal value and capacitor have some serial current throught it, then it is broken. Only charging current is allowed (short current peak on connect).
Sorry for my english.
Good article. I have personally made this repair sucessfully many times using only a basic hand held solding iron and hand held desolder pump.Reply
Like you say the motherboard sinks away the heat fast. You need an iron with between 70 and 100 watts and a large flat tip. If it spans both solder points of the cap its really easy :)
Just heat and gently pull the cap out from the other side of the board. Then clear the holes with the heated pin method or use a desolder pump. If you heat the hole on one side and use the pump on the other side it should clear easily.
Only other thing to note is. Be QUICK, practice on some junk board first, you dont want to burn a big hole in your board or lift of the tracks.
Im sure most people don't have a professional solder/desolder station. These cost at least $160 usually more.
Another trick. Assuming the old caps are dead and of no further use. Pull them off thier leads.Reply
If you pull a electrolytic capacitor hard the leads will pull straight out of the body of the cap.
Leaving just the leads sticking up. Its now much easier to remove becuase you can desolder the leads and remove them one at a time.
Just trim the leads sticking out of the bottom of the board then heat one at a time while applying slight pressure to the capacitor towards the other lead. They pop right out. I use thecapking for capacitors online, fast free shipping.Reply
I use the Weller WLC100. It's consumer DIY soldering station, but more than meets the needs for motherboard soldering. Runs about $50. I've done 50+ boards easily with this station, but I use a precision tip instead of the big tip it comes with (usually run about $10). I also recommend Mouser or Digikey for capacitors, though beginners may find these sites overwhelming. TheCapking is a good place to find capacitor kits for common motherboards with faulty capacitors, and the site has diagrams in case you get confused where the capacitors need to go.Reply
ooowowwwwww nice i am verry happy he he he he....... i likedReply
I Turned on a computer that had been working. A short "pop", a fairly intense burning odor, and later I found a capacitor (I presume) on the bottom of my computer case:Reply
Here is a pic of the Asus P5-K. The green arrow points to where the capacitor used to sit.
First of all I'd like to know if it is indeed a capacitor and if not, what it is. Whatever it is, can I get another, solder it in and have any hope of fixing this board? I'm really clueless, if you can't tell. Any help would be greatly appreciated. This could be an opportunity for me to learn something.
I have a MSI mobo which I repaired some months back...replaced 2 caps. Lately, the same symptoms re-occured..pc starts up, fans run, lights light up but nothing else..no sound, no bios, no display. I replaced the same caps again thinking it might be malfunctioning but still nothing and no signs of any other failure. Any advice? My pc is a Acer Veriton M464 duo core.Reply
Once you pull a mother board for any bad caps, you should replace them all. The caps are cheap compared to the down time and frustration. Some caps can fail with no obvious signs from the outside. My advise would be to change all the old caps with new low ESR Caps.Reply