How to Fix Your Desktop Motherboard capacitor problems

How to Solder/De-solder Capacitor From Your Motherboard

The capacitor is the common premature failure of motherboards, video cards, LCD monitors, and power supplies of personal computers. An incorrect electrolyte formula within a faulty capacitor causes the production of hydrogen gas leading to bulging or deformation of the capacitor’s case, and eventual venting of the electrolyte. In rare cases, faulty capacitors have even been reported to pop or explode forcefully.


How to identify bad capacitors

· Bulging capacitors

· The most common method of identifying capacitors which have failed because of bad electrolyte is visual inspection.

· The capacitance value may degrade to 4% of the original value, as opposed to an expected 50% capacity degradation

· Bulging of the vent on the top of the capacitor.

· Sitting crooked on the circuit board as the bottom rubber plug is pushed outbr>

· Electrolyte (a crusty brown substance) leaked onto the motherboard from the base of the capacitor or vented from the top

· High equivalent series resistance (ESR) can easily be measured without disconnecting capacitors (in-circuit) with an ESR meter if available.

· Failed Tayeh capacitors both of which have vented through their aluminium tops.

As the capacitor ages, its capacitance decreases and its (ESR) increases. When this happens, the capacitors no longer adequately serve their purpose of filtering the direct current voltages on the motherboard, and system instability results.

Some common symptoms are:

o Not turning on all the time; having to hit reset or try turning the computer on again

o Instabilities (hangs, BSODs, kernel panics, etc.), especially when symptoms get progressively more frequent over time

o Memory errors, especially ones that get more frequent with time

o Spontaneous reboots

o In case of on-board video cards, unstable image in some video modes

o Failing to complete the POST, or rebooting before it is completed

o Never starting the POST; fans spin but the system appears dead

o Capacitors with high ESR can make power supplies malfunction,

sometimes causing further circuit damage. CPU core voltage or other

system voltages may fluctuate or go out of range, possibly with an

increase in CPU temperature as the core voltage rises

This failed capacitor can explode and blown its casing off

Failed capacitor from a PC power supply can blow off the board and expelled its contents Unlike the physical signs which are conclusive evidence the capacitors are failing, many of the operational signs may be caused by other factors, such as a failing power supply, dust clogging a fan, bad RAM, or other hardware problems.Instability, once the operating system has loaded, may indicate a software problem (such as some types of malware, poorly-written device drivers or software), and not a hardware problem at all. If any of these symptoms are experienced, removing the system’s case and inspecting the capacitors, especially those around the CPU, may immediately identify capacitors as the cause. If there are no physical signs, an oscilloscope may be used to examine the AC ripple voltage across capacitors during operation, or an ESR meter to measure ESR when powered down; excessive ripple or ESR is a sign that the capacitors are faulty.

Cause of the failing capacitors

When a faulty capacitor is charged, the water-based electrolyte becomes unstable and breaks down, producing hydrogen gas. Since these types of capacitors are sealed in an aluminium casing, the pressure builds up within the capacitor until either the flat metal top of the capacitor begins to bend, or the rubber sealing plug is pushed down. Eventually the pressure exceeds the strength of the metal casing and venting occurs, either by blowing out the rubber bottom of the capacitor, or bursting the scored metal vent on the top of the capacitor. When an electrolytic capacitor bursts, effects can range from a pop and a hissing noise to a small explosion. Venting is typically messy, and the corrosive electrolyte must be cleaned off

When a Motherboard Fails


Hardware failures can have mysterious faces – computer crashes, display anomalies or read/write errors when accessing a hard drive. Usually, what you do is install new drivers, then you look at adjusting settings within your operating system, you search BIOS for relevant options or go the whole nine yards and exchange components such as the main memory. But your computer just won’t run smoothly.

Not only operating systems or device drivers cause system malfunctions. Not even the latest hardware such as quad core processors and terabyte hard drives can prevent hardware failures. Hardware manufacturers typically define a certain lifetime for every component of your computer or laptop. This tends to be five years for hard drives, but other components may have longer life expectancies. Building blocks such as processors, memory, motherboards or graphics card usually keep working for much longer – if always operated and cooled properly. But no crystal ball can tell you precisely how long an electronic product will last. Electrolytic capacitors on numerous semiconductor-based products such as motherboards or graphics cards can often cause computer to behave strangely if they fail. What can you do if malfunctioning motherboard capacitors are the reason for trouble with your computer? If the mobo is under warrantee you can return it for a replacement. If you have to exchange a faulty motherboard for a new and different one, you may also need new memory as well as a new processor. There is a considerably less expensive solution. You can replace faulty electrolytic capacitors yourself. I will show you how to revive a motherboard or graphic card with the right tools and for very little money.

Capacitors – Mysterious Creatures


Capacitors and resistors are the components most frequently used in electric and electronic circuits. Capacitors are used for duplexers, oscillator circuits, as interference suppressors or in the form of electrolytic capacitors filtering of various kinds. Electrolytic capacitors differ from normal capacitors because they use a liquid, an “electrolyte” within their aluminum bodies, conducting electricity when a voltage is applied. Almost all electronic circuits in power supplies use filter capacitors. These deal with electrical peaks transformers or transistors are unable to handle quickly enough. Broadly speaking, a capacitor doesn’t work much different than a rechargeable battery. It will recharge when DC voltage is applied. The capacitor’s charge is stored when the voltage source and the capacitor are disconnected. Filtering capacitors equalize voltages, in power adapters, for example. Transformers will down-transform a power adapter’s voltage to the desired level. Rectifiers generate DC voltage from the applied AC voltage. The freshly generated DC voltage is not “smooth”, rather it pulsates. The brief voltage drop caused by this pulsation is covered by a capacitor, which functions like an additional voltage source providing a stabilizing amount of voltage. Capacitors with lower Equivalent Series Resistance (ESR) are used to make sure that the stabilization works properly and capacitors are able to cover pulsing without being damaged themselves.

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.

How To Recognize Flawed Capacitors


Our capacity gauge shows 1000µF, indicating that this capacitor retains full capacity.

An exploded exterior reveals a broken capacitor. A lumpy top or even an opening at the predetermined breaking point are clear indicators that a capacitor is about to die, if it hasn’t died already. From time to time, the rubber plug, closing the capacitor on the bottom, gets pushed out by gas pressure inside the body. It is especially difficult to detect broken capacitors, whose electrolyte drained over time and didn’t leave any traces on the aluminum body. The dryer a capacitor, the less capacity it has to store electric charge. You definitely need a capacity gauge (see picture) to measure the capacitor. You can get these devices for less than $30. We use a Digitek DS-568F, which was sufficient for our purpose and at less than $40 it was affordable as well.

Welcome to the Emergency Room


We found a several year old board from MSI in our shelves. Defective capacitors are a problem with mobos from just about all manufacturers. So, please don’t take our choice of product as an indictment of MSI. The motherboard just happened to be hanging around our lab, so we used it. Due to its dual processor sockets, we believe that the K7Master is well suited to reanimation. Exchanging this motherboard for another would entail replacing the two processors as well as RAM (registered DDR memory in this case), which would be an economic nightmare. We could not see if all capacitors had deteriorated. However since they were all of the same kind, we assumed that all of them needed replacement. So we began a search for 26 substitute capacitors with equal capacity.

How To Buy Substitute Low-ESR Capacitors


These are simple, radial electrolyte capacitors.

It was more difficult to buy special low ESR capacitors than we thought, since we kept an eye on cost. We think it makes sense to exchange capacitors if the process is inexpensive

– keep in mind that the replacement process itself can go wrong and you would have to purchase a new motherboard plus processor(s) and RAM. We needed 26 radial capacitors with a 1000µF capacity, 6.3 V and 105°C temperature resilience for our K7D Master. You can find the technical data on the capacitor’s case. The capacitor’s diameter is about 8 mm, its height is 16 mm, and the distance between the pins (anode and cathode) is 3.5 mm.


These are the capacitors we ordered.

After a little research we placed our order with a small dealer selling capacitors at scaled prices. We didn’t get the desired capacitors with 6.3 V, but decided to go with 10 V models instead. Pin distance and diameter are the same on the replacement capacitors, but the new ones are 20 mm high instead of 16 mm. Depending on the motherboard you’re repairing, 4 mm can cause some trouble. Before you order any replacement please findout how much space there is between the capacitors and expansion c ards such as your graphics card, among others. We did not encounter any problems with a 4 mm difference in height. We paid 50 cents each for our 30 capacitors, shipping and handling not included.

Let’s Get Started!

Appropriate Tools


This is a processor-controlled soldering/de-soldering station.

Before we start, note that you must conduct all further steps at your own risk. We recommend this task only for users who have had experience using soldering tools. Tom’s Hardware assumes no liability for any damage to the motherboard, the capacitors or you. Professional de-soldering tools are essential for soldering work. Neither manual soldering irons nor de-soldering pumps are suitable, since heating and removing the soldering tin has to take place in a single process. Otherwise, the soldering tin will solidify immediately. The motherboard itself absorbs a lot of heat, which makes de-soldering difficult. Your de-soldering tools’ soldering tip should be 0.8-1.0 mm in diameter, so the soldering tin can easily be sucked away from the soldered spot. In our lab, we used a rather old processor-controlled soldering/de-soldering station called the PLE-9001. Another manufacturer of professional level soldering/de-soldering tools is ERSA.


Desoldering iron with electronic suction pump

In addition, we need solder and electronic diagonal cutting pliers. The latter is smaller than a normal side cutter and is therefore handier for delicate work. A small bench vise with plastic chucks is also helpful to hold the motherboard in a vertical position while soldering. Make sure you attach the vise at an appropriate location and do not pull it too tight.

De-Soldering Capacitors

After chucking the motherboard into the vise, locate the faulty capacitors on the motherboard’s topside and de-solder the capacitors from the bottom side with your soldering iron and pump.




Drilling the motherboard

Sometimes the solder just won’t come off the soldered spot, no matter how much heat you apply and no matter how well you use the de-soldering pump. We need to open a small hole for the capacitor pin at the soldered spot. So, we take a small metal pin (diameter 0.8 mm), hold it at the soldered spot with small pliers, and carefully heat it with the soldering iron. If all goes well, you will be able to remove the now liquid solder from the small hole in the motherboard. But please be careful when doing so: If you apply too much pressure to the metal pin, you might damage delicate adjacent conducting paths.


Clear the soldering spots with a metal pin.

If you’re still not successful in clearing the hold in the motherboard, try drilling a hole in the soldered spot. We advise against this procedure! You should only try it, if neither de- soldering with a soldering iron, nor the metal pin approach works.


Drilling the motherboard – this should only be your last resort.

Equip Your Motherboard With New Capacitors

We have de-soldered all flawed capacitors from the motherboard and can now install our replacements. Watch the capacitors’ polarity. If you confuse plus with minus, the capacitor will explode and you will have put in a lot of hard work for nothing. New capacitors come with a longer-legged plus pole. To make sure you get things right, take a close look at the capacitor. It is clearly labeled, e.g. with numerous “minus” symbols and an arrow pointing at the associated leg. Both poles are also clearly tagged on your motherboard.




Watch the polarity when replacing the capacitors on a motherboard.


Moving the capacitor all the way down


Slightly bend anode and cathode (legs) to the side, so the capacitors won’t fall out after placing them on the motherboard.


Soldering the capacitors…


...and pruning left-over material.


Done! Ideally, at this point the motherboard should be ready for operation.


In case of a motherboard failure. This is especially annoying if the costs for substitute parts are only in the cent-range, which typically is the case with leaked capacitors. Although motherboard makers increasingly use solid capacitors free of electrolyte, flawed electrolytic capacitors are still one of the main reasons for defective motherboards. In a worst case scenario, you should consider your next steps carefully. Even if your product is still covered by a warranty, your retailer might not be able to replace the broken motherboard instantly. Reasons might be that he is simply out of spare parts or because he insists on not applying the warranty, since the capacitors were most likely intact when purchased. Exchanging your motherboard might entail undesired additional costs for the purchase of a new processor or processors and new RAM. But wait – there is another way: If you know for sure that malfunction is caused by flawed capacitors, you can try to revive the motherboard by single-handedly exchanging leaked or broken capacitors. The cost of our project added up to $15. If you are a little talented in handicraft and have access to the appropriate tools, you might as well try saving that three-digit sum for replacing the board, the processor and the memory. And these savings don’t only apply to motherboards: Exchanging defective capacitors is also possible on graphics cards. Really talented hobbyists can exchange several capacitors in less than an hour, since the work process is not that complex – provided that you have the right tools. Less experienced users might fail because they lack the appropriate tools. In this case, why not try a local radio and TV technician? If the thought of soldering a motherboard is simply unbearable for you, just consider one thing: practically, the motherboard is already dead. Why not give it a try?

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