Narcoleptic Aluminum Powerbook Syndrome

Narcoleptic Aluminum Powerbook Syndrome (NAPS), also known as Random Overtemp Sleep Syndrome (ROSS) is a fault inherent to Apple Computer’s Powerbook G4 Aluminum series of laptop computers, most notably the 15” 1.67 GHz model, but has also been known to occur in 12” and 17” models. The symptoms are described as the computer entering sleep-mode at random, and occasionally a deep sleep where the computer is no longer responsive to keyboard wake-up, nor emergency shut down via the power button. The problem is caused by a faulty trackpad temperature sensor that causes the system to believe that it is overheating, thus triggering an emergency overtemp sleep. A similar but unrelated problem exists that is caused by a faulty ambient light sensor.
Signs and Symptoms
The problem manifests itself as a sudden and unprompted sleep whereby the screen goes black, and the white LED on the front of the case pulses, regardless of battery charge or other power-saving parameters. The computer may be woken from sleep by pressing the keyboard, but may then go back into sleep as quickly as several seconds later, or may continue to function for several minutes, hours or days until the next sleep. Occasionally the computer may enter a “deep-sleep” whereby it cannot be woken by pressing the keyboard, nor shut down by holding down the power button for 5 seconds (emergency shut down). The computer may stay in this state for several minutes or hours until it becomes responsive to the keyboard and can be woken again. However, holding down the power button for an extended duration of 10-15 seconds has been found to wake the system in this situation.
Diagnosis
The problem can be diagnosed using the freeware Mac program "Temperature Monitor" and displaying the trackpad sensor as a graph using the "Show History Windows" function. A sensor in working order will show readings similar to the PowerBook's other 5 temperature sensors. A symptomatic faulty sensor will show random spiking of extreme highs and lows, often below 0ºC and above 100ºC, and may also show periods of non function where no data is recorded, mixed with periods of operation where normal temperatures are recorded.
Cause
The problem is caused by a design flaw in the Powerbook G4 Aluminum series of laptops, whereby the trackpad temperature sensor is vulnerable to mechanical stress due to its exposed location between the trackpad and spacebar. Downward forces created by average use are enough to cause the temperature to eventually malfunction. This has been known to happen after as little as one year of average use, but systems typically become symptomatic after extended use, or heavy typing/gaming. After the temperature sensor is damaged, it malfunctions at random; either occasionally, or for prolonged “fits”.
Cure
Several attempts by the general public were been made to edit the Mac OS X kernel so that the system would no longer read data from the faulty sensor, but these failed to solve the problem and risked causing irreparable damage to the operating system, as well as leaving the system vulnerable to genuine over heating. The only solution that has been found to work without fail is the removal of the faulty temperature sensor itself. The temperature sensor is a 2mm long black integrated circuit or microchip with 2 legs on one side and 3 on the other, housed in the area between the trackpad and spacebar on the underside of the keyboard housing and mounted on an orange ribbon. It is removed by opening the computer and freeing the chip leg-by-leg from the orange ribbon on which it is mounted either with a soldering iron or with a precision cutting tool such as cuticle nippers. Care must be taken to remove any excess solder or metal leg afterwards and cover the area with insulation tape to prevent shorting.On restart, the system will list the trackpad sensor as "disconnected" in the Temperature Monitor software.
Official Support
Apple neither officially recognises the problem nor provides any software, firmware, or hardware fix. Typically, an Apple service center or "Genius Bar" will attempt to solve the problem by replacing the entire logic board.

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