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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. INCIDENCE Faulty capacitors have been discovered in motherboards as old as . Apple has also introduced an extended free repair program for early iMac G5's suffering from the problem {Link without Title} . with failed capacitors.]] While this article deals primarily with desktop computer hardware, this problem is by no means limited to that area. These capacitors can also be found in some cameras, network switches, audio equipment, DVD players, and a range of other devices. Even some car Electronic Control Unit s have been found to have these same brands of often-failing capacitors. However, computer components are by far the most common location of these capacitors. The fact that these failure-prone capacitors are still being used has angered many people, especially in cases where a motherboard populated mainly with high quality capacitors has one or two of the bad capacitors on it, leading to accusations of Planned Obsolescence on the part of motherboard manufacturers. Indeed, a strong case can be made that these capacitors (which often fail in 6 months or less) are still being manufactured, and are still being chosen over superior components by manufacturers to use in their products. As of May 2005, {Link without Title} some evidence shows that the failing Nichicon capacitors on the iMac, Intel, and Dell boards are due to a different problem (capacitors overfilled with electrolyte) than the one discussed on this page (faulty electrolyte formula). However, both the effects on the system and the physical appearance of the capacitors are the same as the other failing capacitors, as is how to identify them, and the required repair. IDENTIFYING "CAPACITOR PLAGUE" The most common way of identifying capacitors failing due to this cause is physical deformations:
As the capacitor ages, its Capacitance decreases while its Equivalent Series Resistance (ESR) increases. When this happens, the capacitors no longer adequately serve their purpose of filtering the Direct Current Voltage s on the motherboard, and system instability results. Some common symptoms are:
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 voltage on the capacitors, with excessive Ripple Voltage being a sign the capacitors are not doing their job. CAUSE OF THE FAILING CAPACITORS The primary cause of these problems is Industrial Espionage gone wrong, with some Taiwanese electrolyte manufacturers using a stolen formula that was incomplete, and lacked ingredients needed to produce a stable capacitor. 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 Aluminum casing, the pressure builds up within the capacitor until either the flat metal tops 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 capacitors bursts, effects can range from a pop and a hissing noise to a small explosion. Venting is typically messy, and the acidic electrolyte must be cleaned off the motherboard to prevent further damage. Sadly, once the problems with these capacitors became known, there is evidence that motherboard manufacturers continued to use the bad capacitors either knowingly or unknowingly. Only ABIT has admitted to the problems, while other manufacturers have given responses ranging from ignorance to denial. Some have gone so far as to issue legal threats to web sites mentioning their names in conjunction with capacitor failures. IEEE 's Spectrum has an overview of the situation, aptly titled "Leaking Capacitors Muck up Motherboards", after the tendency of the capacitors to leak their fluid onto the motherboard. REPLACEMENT OF FAILING CAPACITORS Some repair personnel are willing to perform the labor intensive task of replacing motherboard capacitors (typically referred to as "recapping"), however the cost of having a technician repair the board often costs more than simply purchasing a replacement board of equal or even greater value, depending on the country. Furthermore, recapping a motherboard does not guarantee its revival as neighboring components can be damaged by leaked electrolyte and can also be damaged by heat during the soldering process, especially if the person attempting the repair is unskilled. Soldering on motherboards, which are typically made of six or more layers, some of which may have Ground Plane s, and may use Lead-free Solder requiring higher temperatures than leaded solders, can be challenging. Attempting a repair without the right equipment and skills can easily destroy an otherwise repairable board. Before replacing the capacitors on a motherboard, research has to be done into the proper low- ESR replacements and best soldering methods for the board in question. During the repair process special care should be taken to protect the hands and eyes as capacitor fluid is Acid ic. Recapping on a power supply unit should NEVER be attempted by a non-professional as dangerous voltages can remain present across the unit's functioning capacitors for as long as days even after being unplugged. As is common with motherboards, it is usually more cost effective to purchase a replacement unit rather than to attempt the repair. BRANDS AND SPECS Bad
Suspicious brands
Admitted
Possibly reformed
Good
SPECIFICATIONS OF CAPACITORS USED ON MOTHERBOARDS Typically, only the capacitors with capacitances over 480 µF fail, since the lower capacitance ones are usually made with a different electrolyte. When motherboards are recapped, only the ones over 480 µF are replaced for this reason. However, some smaller values have been known to fail, so sometimes replacing every vented electrolytic is necessary to permanently repair a motherboard. Any motherboard with these brands of capacitors is very likely to fail prematurely, and due to the possibility of bad capacitors damaging other components, a preemptive replacement of the capacitors is sometimes advisable. CONSEQUENCES OF CAPACITOR FAILURE While failing capacitors typically results in the aforementioned system instabilities, occasionally failed capacitors, especially on certain motherboards, will lead to a failure of the Voltage Regulator s on the motherboard. There are two common theories on why this happens: The first (and simpler) theory is that the failing capacitors can fail such as to form a Short Circuit , or with a very high Leakage current, overloading the voltage regulators and causing them to overheat. The second theory is that as the capacitance decreases and the ESR increases, the Buck Controller for the voltage regulator increases the switching frequency to compensate. Since most of the MOSFET 's heat output is produced during the switching transitions, this causes them to overheat. The most common failure mode of the voltage regulator is for the MOSFET to short circuit, causing the system's power supply (5 or 12 Volt s depending on the motherboard) to be applied directly to the CPU, Northbridge , RAM, or other components, causing widespread damage and destruction. As such, a motherboard with symptoms of failing capacitors should be taken out of service until it is repaired, to prevent further damage. EXTERNAL LINKS
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