Motherboard Repair

5/26/2018 Motherboard Repair

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How to Fix Your Motherboard for $15

* Solder/De-solder Capacitor From Your Motherboard

* When a Motherboard Fails

* Capacitors - Mysterious Creatures

* When Capacitors Spring Leaks

* How To Recognize Flawed Capacitors

* How To Buy Substitute Low-ESR Capacitors

* Let's Get Started!

* De-Soldering Capacitors

* Drilling the motherboard

* Equip Your Motherboard With New Capacitors

* Conclusion


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Solder/De-solder Capacitor From Your Motherboard

The capacitor is the common premature failure of motherboards, video cards, LCDmonitors, and power supplies of personal computers. An incorrect electrolyte formulawithin a faulty capacitor causes the production of hydrogen gas leading to bulging ordeformation 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.


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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. Whenthis happens, the capacitors no longer adequately serve their purpose of filteringthe 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 computeron again

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

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


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o Spontaneous rebootso In case of on-board video cards, unstable image in some video modeso Failing to complete the POST, or rebooting before it is completedo Never starting the POST; fans spin but the system appears deado Capacitors with high ESR can make power supplies malfunction,

sometimes causing further circuit damage. CPU core voltage or othersystem voltages may fluctuate or go out of range, possibly with anincrease 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 itscontents Unlike the physical signs which are conclusive evidence the capacitorsare 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 hardwareproblems.

Instability, once the operating system has loaded, may indicate a softwareproblem (such as some types of malware, poorly-written device drivers orsoftware), and not a hardware problem at all.If any of these symptoms are experienced, removing the system's case andinspecting the capacitors, especially those around the CPU, may immediatelyidentify capacitors as the cause.If there are no physical signs, an oscilloscope may be used to examine the ACripple voltage across capacitors during operation, or an ESR meter to measureESR when powered down; excessive ripple or ESR is a sign that the capacitorsare faulty.

Cause of the failing capacitorsWhen a faulty capacitor is charged, the water-based electrolyte becomes unstableand breaks down, producing hydrogen gas. Since these types of capacitors aresealed in an aluminum casing, the pressure builds up within the capacitor untileither the flat metal top of the capacitor begins to bend, or the rubber sealing plugis pushed down. Eventually the pressure exceeds the strength of the metal casingand venting occurs, either by blowing out the rubber bottom of the capacitor, orbursting the scored metal vent on the top of the capacitor. When an electrolyticcapacitor bursts, effects can range from a pop and a hissing noise to a smallexplosion. Venting is typically messy, and the corrosive electrolyte must becleaned off

When a Motherboard Fails


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

Not only operating systems or device drivers cause system malfunctions. Not even thelatest hardware such as quad core processors and terabyte hard drives can preventhardware failures. Hardware manufacturers typically define a certain lifetime for everycomponent of your computer or laptop. This tends to be five years for hard drives, butother components may have longer life expectancies. Building blocks such as processors,memory, motherboards or graphics card usually keep working for much longer - ifalways operated and cooled properly. But no crystal ball can tell you precisely how longan electronic product will last.

Electrolytic capacitors on numerous semiconductor-based products such as motherboardsor graphics cards can often cause computer to behave strangely if they fail. What can youdo if malfunctioning motherboard capacitors are the reason for trouble with yourcomputer? If the mobo is under warrantee you can return it for a replacement. If you haveto exchange a faulty motherboard for a new and different one, you may also need newmemory as well as a new processor. There is a considerably less expensive solution. Youcan replace faulty electrolytic capacitors yourself. I will show you how to revive amotherboard or graphic card with the right tools and for very little money.


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Capacitors - Mysterious Creatures


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Capacitors and resistors are the components most frequently used in electric andelectronic circuits. Capacitors are used for duplexers, oscillator circuits, as interferencesuppressors or in the form of electrolytic capacitors filtering of various kinds. Electrolyticcapacitors 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. Broadlyspeaking, a capacitor doesn't work much different than a rechargeable battery. It willrecharge when DC voltage is applied. The capacitor's charge is stored when the voltagesource and the capacitor are disconnected. Filtering capacitors equalize voltages, inpower 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


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voltage is not "smooth", rather it pulsates. The brief voltage drop caused by this pulsationis covered by a capacitor, which functions like an additional voltage source providing astabilizing amount of voltage. Capacitors with lower Equivalent Series Resistance (ESR)are used to make sure that the stabilization works properly and capacitors are able tocover 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, electrolytesused in low ESR capacitors have to be especially conductive. To increase theconductibility of the electrolyte, you add additives. One of these additives is water. Andbecause of this water allotment, the number of free ions and therefore the electronicconductibility increases.

However, unclean water can attack the aluminum body of the capacitor, which causescorrosion. The corrosion process creates gases inside the capacitor, increasing the interiorpressure - you can see a failing capacitor turn lumpy. The top of the capacitor has apredetermined 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. Thesame thing happens in case of extreme overvoltage. The electrolyte still present canpollute the motherboard and cause short circuits, which might even set a computer onfire. Motherboard breakdowns caused a number of problems between 1999 and 2005 forsome manufacturers. Capacitors with improper or low-grade electrolytes were used,causing numerous failures and a drastic decrease in motherboard life.


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But not only unclean electrolytes can damage capacitors. Like any other liquid, theelectrolyte can simply change its physical condition and evaporate. This happens not onlywhen a system is in operation, but can also occur while the system is shut down or themotherboard is stored somewhere. We all know that components such as RAM and CPUsbenefit from proper cooling. Cooling also increases the life expectancy of capacitors,

since the probability of evaporation correlates with ambient temperature. An unwrittenlaw says that a 10C drop in temperature doubles the life expectancy of a capacitor.

How To Recognize Flawed Capacitors

Our capacity gauge shows 1000F, indicating that this capacitor retains fullcapacity.

An exploded exterior reveals a broken capacitor. A lumpy top or even an opening at thepredetermined 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 thebottom, gets pushed out by gas pressure inside the body. It is especially difficult to detectbroken capacitors, whose electrolyte drained over time and didn't leave any traces on thealuminum 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 getthese devices for less than $30. We use a Digitek DS-568F, which was sufficient for ourpurpose and at less than $40 it was affordable as well.


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Welcome to the Emergency Room

We found a several year old board from MSI in our shelves. Defective capacitors are aproblem with mobos from just about all manufacturers. So, please don't take our choiceof product as an indictment of MSI. The motherboard just happened to be hanging aroundour lab, so we used it.

Due to its dual processor sockets, we believe that the K7Master is well suited toreanimation. Exchanging this motherboard for another would entail replacing the twoprocessors as well as RAM (registered DDR memory in this case), which would be aneconomic nightmare.

We could not see if all capacitors had deteriorated. However since they were all of thesame kind, we assumed that all of them needed replacement. So we began a search for 26substitute capacitors with equal capacity.


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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 aneye 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 topurchase a new motherboard plus processor(s) and RAM.

We needed 26 radial capacitors with a 1000F capacity, 6.3 V and 105C 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 thepins (anode and cathode) is 3.5 mm.


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These are the capacitors we ordered.

After a little research we placed our order with a small dealer selling capacitors at scaledprices. We didn't get the desired capacitors with 6.3 V, but decided to go with 10 Vmodels instead. Pin distance and diameter are the same on the replacement capacitors, butthe new ones are 20 mm high instead of 16 mm. Depending on the motherboard you'rerepairing, 4 mm can cause some trouble. Before you order any replacement please findout how much space there is between the capacitors and expansion cards such as yourgraphics 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 notincluded.


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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. Werecommend this task only for users who have had experience using soldering tools. Tom'sHardware assumes no liability for any damage to the motherboard, the capacitors or you.

Professional de-soldering tools are essential for soldering work. Neither manual solderingirons nor de-soldering pumps are suitable, since heating and removing the soldering tinhas to take place in a single process. Otherwise, the soldering tin will solidifyimmediately. The motherboard itself absorbs a lot of heat, which makes de-solderingdifficult.

Your de-soldering tools' soldering tip should be 0.8-1.0 mm in diameter, so the solderingtin can easily be sucked away from the soldered spot. In our lab, we used a rather oldprocessor-controlled soldering/de-soldering station called the PLE-9001. Anothermanufacturer of professional level soldering/de-soldering tools is ERSA.


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De-soldering iron with electronic suction pump

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

tight.


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De-Soldering Capacitors

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


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Drilling the motherboard

Sometimes the solder just won't come off the soldered spot, no matter how much heatyou apply and no matter how well you use the de-soldering pump. We need to open asmall 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 withthe soldering iron. If all goes well, you will be able to remove the now liquid solder fromthe small hole in the motherboard. But please be careful when doing so: If you apply toomuch 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 inthe 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.


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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 ourreplacements. Watch the capacitors' polarity. If you confuse plus with minus, thecapacitor will explode and you will have put in a lot of hard work for nothing. Newcapacitors come with a longer-legged plus pole. To make sure you get things right, take aclose look at the capacitor. It is clearly labeled, e.g. with numerous "minus" symbols andan arrow pointing at the associated leg. Both poles are also clearly tagged on yourmotherboard.


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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 afterplacing them on the motherboard.

Soldering the capacitors...


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...and pruning left-over material.

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


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Conclusion

In case of a motherboard failure. This is especially annoying if the costs for substituteparts 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 defectivemotherboards. 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 toreplace the broken motherboard instantly. Reasons might be that he is simply out of spareparts or because he insists on not applying the warranty, since the capacitors were mostlikely intact when purchased. Exchanging your motherboard might entail undesiredadditional 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 byflawed 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 littletalented in handicraft and have access to the appropriate tools, you might as well trysaving that three-digit sum for replacing the board, the processor and the memory. Andthese savings don't only apply to motherboards: Exchanging defective capacitors is alsopossible on graphics cards.

Really talented hobbyists can exchange several capacitors in less than an hour, since thework process is not that complex - provided that you have the right tools. Lessexperienced users might fail because they lack the appropriate tools. In this case, why nottry a local radio and TV technician? If the thought of soldering a motherboard is simplyunbearable for you, just consider one thing: practically, the motherboard is already dead.

Why not give it a try?

Motherboard Repair

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