Wednesday, 12 September 2012

Heat



The battery life of a laptop is a major marketing tool for manufacturers.  When laptops are designed, makers probably use every technique possible to maximize battery life.  The cooling fans fitted to laptops are probably set to cut in and run at speeds which meet both the competing requirements of adequate heat removal and maximum battery life.  The designed in fan cut in temperature and fan speeds are thus probably the result of  a compromise that works ok when the laptop is young and when it is used only within certain environmental conditions. 

Many people over the years have expressed the view that laptops would last longer if heat removal was improved by one means or another. For Mac computers and particularly Mac laptops, there is a program that allows the user to dial in a lower than standard fan cut in temperature and higher than standard fan speeds.

The program is called SMC Fan Control and is available here: http://www.eidac.de/

I use it all the time.  SMC Fan Control displays a temperature read out on the upper task bar. Even if you keep the fan cut in and speeds standard, you can see how hot your Mac is running.

People discuss their hot Macs in this forum thread: http://forums.macrumors.com/showthread.php?t=433732


While the Intel CPU is protected by a thermal cut out, the constant heat inside a laptop case impacts on the life of other components. Especially, in my opinion,  the tiny capacitors which pepper the circuit boards. As the fluid inside modern capacitors may be mildly corrosive,  the life of these capacitors is greatly shortened by hot environments. But that’s just my opinion.

Some suggestions for reducing the temperature of the Macbook are discussed here: http://timemanagement.cgpgrey.com/5-ways-to-cool-down-your-hot-macbook/

The Macbook is a plastic bodied machine.  The components inside the Macbook, including the logic board and heat sink, are attached to the plastic base by screws threaded into metal inserts inside plastic mounts. 

When plastic, even polycarbonate, gets hot, it becomes less rigid and more flexible.  Proper heat removal from the CPU depends upon the proper mounting of the heat to the CPU. Thermal grease, applied to the top of the CPU conducts heat from the CPU to the heat sink.  Briefly, the airflow caused by the fan  is supposed to adequately remove the heat from the heat sink.

If the heat sink is loose or if the thermal grease is old and inefficient, a macbook will run hot. And sometimes it will cut out. Its life span is being reduced by poor heat removal.

 If you have the Apple Macbook take apart and service manual you will be able to read the specified manner in which new thermal is applied. You will also see the specific manner in which the heat sink is secured to mounts and thus clamped to the top of the CPU. 

Apple does not release its service manuals to the public. They can be found at a few sites on the internet however.  Too much thermal grease is as bad as not enough. You must use the right sort of thermal grease. 

Here is IFixit’s guide to replacing thermal grease:


Please research this whole issue further before deciding on taking any action on your MacBook. If your heat sink is not loose and if the SMC temperature read out shows an idle temp of 40 – 50 degrees Celcius in a room temperature of about 25 degrees Celcius, I would do nothing.  But that is just my belief.  

Capacitors

Wikipedia reports the infamous period during which bad capacitors flooded the electronics supply chain in, particularly in years past:

“The capacitor plague (also known as bad capacitors or "bad caps")[1][2] is a problem with a large number of premature failures of aluminum electrolytic capacitors with non-solid or liquid electrolyte of certain brands, especially from some Taiwanese manufacturers.[3][4][5]

The first flawed capacitors were reported in 1999, but most of the affected capacitors failed in the early to mid 2000s. High failure rates occurred in various electronics equipment, particularly motherboards, video cards, compact fluorescent lamp ballasts, LCD monitors, and power supplies of personal computers. News of the failures (usually after a few years of use) forced many equipment manufacturers to repair the defects. The problem seems to be ongoing; faults were still being reported as of 2010.[6]….. Problems with "bad caps" have affected equipment manufactured up to at least 2007 and beyond.[9] Many well-known motherboard companies have unknowingly assembled and sold boards with faulty capacitors sourced from other manufacturers. Major vendors such as IBM, Intel, Dell, HP, Samsung, and Apple Inc. were affected.[7][10] Circa 2005, Dell spent some US$150 million replacing motherboards outright and another US$150 million on the logistics of determining whether a system was in need of replacement. HP reportedly purged its product line in 2004. The motherboards and power supplies in the Apple iMac G5[11] and some eMacs[12] were also affected.
While the capacitor plague has affected large numbers of desktop computers, the problem is by no means limited to that category. Bad capacitors can also be found in external power supply adaptors, network switches, audio equipment, flat panel displays, and a wide range of other devices. "Bad caps" can cause a simple failure to turn on, or a wide range of bizarre (often intermittent) behavior of afflicted electronic equipment……”

Visual symptoms 

Direct visual inspection is a common method of identifying capacitors which have failed because of bad electrolyte. Failed capacitors may show one or more of these visible symptoms:[8]
      Bulging or cracking of the vent on top of the capacitor. (The "vent" is shaped by an impression stamped into the top of the can, forming 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 exploding.)
      Capacitor casing sitting crooked on the circuit board, as the bottom rubber plug is pushed out
      Electrolyte leaked onto the motherboard from the base of the capacitor or vented from the top, visible as crusty rust-like brown deposits. The petroleum-based adhesive that is sometimes used to secure the capacitors to the board can be confused with leaked electrolyte; electrolyte is usually wet, adhesive is dry. The glue is a thick elastic covering usually of a sandy yellow color, which darkens (towards black) with heat. A dark brown crust up the side of a capacitor is invariably glue, not electrolyte. The glue is itself sometimes harmful, and can corrode leads and tracks covered by it, causing leakage current or an open circuit; it is not required and can safely be removed. The presence of black-colored glue is a reliable sign that the capacitor has overheated, due either to internal failure or to inadequate ventilation.
      Detached or missing capacitor casing. Sometimes a failed capacitor will literally explode, ejecting its contents violently and shooting the casing off the circuit board. Grayish aluminum foil and shredded paper (the remnants of the capacitor internals) may still be attached to the circuit board, or scattered in the vicinity.
      Surface Mount Device (SMD) packaging is used for ultra-compact electrolytic capacitors instead of traditional metal cans, for components soldered directly to printed circuit boards. Because these devices are so small, a magnifying glass is useful for visual inspection. The only visible clue to failure may be a small leakage of electrolyte from the package, but often a defective SMD device cannot be identified by its external appearance.
Sometimes, electrolytic capacitors fail without any visible changes in appearance of the external SMD or metal can package. Since the electrical characteristics of capacitors are the reason for their use, these parameters must be tested with instruments to definitively decide if the devices have failed.”  Source: http://en.wikipedia.org/wiki/Capacitor_plague

I believe I’m lucky if a modern capacitor in any of the electrical devices I own last more than 5 years.  But that’s just my belief.   To what extent Apple had solved the problem of bad capacitors in the period 2006 – 2009 (the production life of the A1181 MacBook) I do not know. The problem is industry wide. That means, the whole electronics industry, not just computers.

I’ll give Wikipedia the last say:
Quote: “Computer symptoms
Some common behavioral symptoms of "bad caps" seen in computer systems are:
Intermittent failure to turn on, requiring user to press reset or try turning the computer on repeatedly
Instabilities (hangs, occurrences of the "Blue Screen of Death", kernel panics, etc.), especially when symptoms get progressively more frequent over time
Memory errors, especially ones that get more frequent with time 
Spontaneous restarts or resets
In on-board or add-on video cards, unstable image in some video modes
Failure to complete the Power-On Self Test ("POST"), or spontaneous rebooting before it is completed
Failure to even start the POST; fans spin but the system appears dead….” End quote.  Source:  : http://en.wikipedia.org/wiki/Capacitor_plague
Sound Familiar? See my previous post.

Next: Recording TV, audio and video on a budget. 






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