Capacitor plague

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The capacitor plague (also known as bad capacitors) involved the common premature failure of certain brands of electrolytic capacitors used in various low quality electronics equipment, and particularly in motherboards, video cards, compact fluorescent lamp ballasts, LCD monitors, and power supplies of personal computers. The first flawed capacitors were seen in 1999, but most of the affected capacitors were made in the early to mid 2000s, and while news of their failures (usually after a few years of use) has forced most manufacturers to fix the defects, some bad capacitors were still being sold or integrated into designs as of early 2007^[update].^[1]

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. Although modern manufacturing techniques normally ensure they vent safely rather than explode, manufacturers have been known to omit the key safety features that allow this.

A serious quality control problem is that good and poor quality electrolytic capacitors will often have identical electrical performance when newly fitted. Only extensive accelerated life testing involving abnormally high ripple currents and high operating temperatures can identify inferior components. This contrasts strongly with most electronic components which are much less subject to spontaneous failure after assembly.

Contents 1 Incidence 2 Symptoms 3 Cause of the failing capacitors 4 See also 5 References 6 External links

[edit] Incidence

This section may contain original research or unverified claims. Please improve the article by adding references. See the talk page for details. (May 2008)

Faulty capacitors have been discovered in motherboards as old as Socket 7 and have affected boards manufactured up to the present day. The motherboard companies assembled and sold boards with faulty caps sourced from other manufacturers (see below). The Apple PowerPC^[2] line of the iMac G5^[3] computers and some eMac computers'^[4] motherboards and power supplies were also affected.

While capacitor plague largely affects 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.

Early signs of the capacitor plague began when Taiwanese manufacturer Craven Insurance produced low-quality motherboards as a side profit to prevent liquidation of their Australian insurance company. Craven Insurance has since declared bankruptcy.

Some early brands of surface mount aluminum electrolytic capacitors suffered from an apparently similar, but actually different problem involving electrolyte leakage. Surface mount soldering is usually achieved by first screen printing dabs of solder paste onto the printed circuit board, gluing the components into position, and then running the board assembly through a reflow oven to melt the solder. In an attempt to ensure more reliable soldering, some manufacturers increase the temperature of the reflow, which unknown to them, damages the rubber seals of the capacitors, causing them to dry out or start to leak after one or two years of operation. Compact equipment such as video camcorders are particularly affected by this problem, in most cases becoming uneconomical to repair.

[edit] Symptoms

The most common method of identifying capacitors which have failed because of bad electrolyte is visual inspection. Such a capacitor will show one or more of these symptoms:

• Bulging of the vent on the top of the capacitor. (The 'vent' is the impression stamped in the top of the can. The impression forms the seams of the vent. It is designed so that if the capacitor becomes pressurized it will split at the vent's seams relieving the pressure rather than making it explode.)
• In the case of Dell Optiplex GX270s often a "Thermal Event" is displayed in white on a black screen when rebooting.^[5]
• Sitting crooked on the circuit board as the bottom rubber plug is pushed out
• Electrolyte (a crusty brown substance) leaked onto the motherboard from the base of the capacitor
• Venting from the top of the capacitor, visible as rust-like brown deposits, or a visible hole in the vent.

Note: the electrolyte is usually wet, not dry. Be careful not to confuse electrolyte leakage with the petroleum-based glue (e.g. Evo-Stik) that is sometimes used to secure the capacitors to the board. This glue is a sandy yellow colour but turns darker (towards black) with heat. A dark brown crust up the side of a capacitor is invariably glue, not electrolyte. A common effect is corrosion of component leads covered by the glue, leading to leakage current or open-circuit. The presence of black glue is a sure sign that the capacitor has overheated due either to internal failure or inadequate ventilation.

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 voltages on the motherboard, and system instability results. Some common symptoms are:

• Not turning on all the time; having to hit reset or try turning the computer on again
• Instabilities (hangs, BSODs, kernel panics, etc.), especially when symptoms get progressively more frequent over time
• CPU core voltage or other system voltages fluctuating or going out of range, possibly with an increase in CPU temperature as the core voltage rises
• Memory errors, especially ones that get more frequent with time
• Spontaneous reboots
• In case of on-board video cards, unstable image in some video modes
• Failing to complete the POST, or rebooting before it is completed
• Never starting the POST; fans spin but the system appears dead

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.

[edit] Cause of the failing capacitors

In some cases, the root cause of the failing capacitors is industrial espionage gone wrong. Several Taiwanese electrolyte manufacturers began using a stolen formula that was incomplete, and lacked ingredients needed to produce a stable capacitor.^[6] (An anti-corrosion ingredient was not documented, reported in comp.risks.^[7])

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 acidic electrolyte must be cleaned off the motherboard to prevent further damage.

IEEE Spectrum covered the issue,^[6] and later estimated that the problem cost US$100 million to fix.^[8]

[edit] See also

• Equivalent series resistance
• Equivalent series inductance

[edit] References

1. ^ "Badcaps.net - Badcaps Home". http://www.badcaps.net/.  070405 badcaps.net
2. ^ Repairing Apple iMac G5 PPC Motherboards DIY How-to Guide
3. ^ Apple iMac Repair Extension Program
4. ^ Apple eMac Repair Extension Program
5. ^ PCs plagued by bad capacitors | CNET News.com
6. ^ ^{a b} Chiu, Yu-Tzu; Samuel K. Moore (February 2003). "Faults & Failures: Leaking capacitors muck up motherboards". IEEE Spectrum 40 (2): 16–17. doi:10.1109/MSPEC.2003.1176509. ISSN 0018-9235. http://web.archive.org/web/20030219071949/http://www.spectrum.ieee.org/WEBONLY/resource/feb03/ncap.html. Retrieved on 2008-03-10. 
7. ^ May 2003 comp.risks
8. ^ Pecht, Michael; Sanjay Tiku (May 2006). "Bogus! Electronic manufacturing and consumers confront a rising tide of counterfeit electronics". IEEE Spectrum 43 (5): 37–46. doi:10.1109/MSPEC.2006.1628506. ISSN 0018-9235. http://www.spectrum.ieee.org/may06/3423.  archive.org copy

[edit] External links

• [1] - Carey Holzman claims to be the first journalist to bring this issue to the public's attention and has worked with lawyers to bring settlements from major manufacturers
• BadCaps — A repair site offering tutorials on proper soldering, repair services and replacement capacitors
• Capacitor Replacement Video Tutorial in HD - Explains the basics of replacement capacitor selection and how to replace capacitors
• Capacitor Lab - Repair and bad capacitor information site
• Motherboard Capacitor Problem Blows Up — An article about capacitor failures
• Identification of Missing or Insufficient Electrolyte Constituents in Failed Aluminum Electrolytic Capacitors; Hilman and Helmold, CARTS 2004