Mac reanimieren

Dieses Thema im Forum "How to..." wurde erstellt von Macmacfriend, 27. Juni 2004.

  1. Macmacfriend

    Macmacfriend Active Member

    Kein Startgong, kein Monitorbild, keine Festplattengeräusche - nichts rührt sich ... außer den Nackenhaaren. ;)

    Sofern nicht das Netzteil hinüber ist, hilft hin und wieder ein sogenannter PMU-Reset. Dabei wird das Knöpfchen neben der Pufferbatterie einmal kurz gedrückt.

    Um nichts falsch zu machen, folgt man am besten diesen weisen Ratschlägen:

    <Power Mac G4 (AGP Graphics/Gigabit Ethernet): Resetting the PMU on the Logic Board Three things to consider when troubleshooting the logic board are:

    * the processor module
    * the PMU (Power Management Unit) chip
    * the logic board LEDs

    Read the following information before replacing any modules.

    This article covers repair procedures for authorized service providers on selected Apple products, but we have published them in the Knowledge Base for the general public for educational purposes. At this time, there are a limited number of repairs that a customer can perform and these are covered under the customer installable parts program If you have not been authorized to perform these procedures, please contact Apple (800-APL-CARE in the USA) or your local authorized service provider to schedule a repair.

    The PMU Chip

    The PMU (Power Management Unit) is a microcontroller chip that controls all power functions for the computer. The PMU is a computer within a computer. It has memory, software, firmware, I/O, two crystals, and a CPU. Its functions is to:

    * Tell the computer to turn on, turn off, sleep, wake, idle, etc.
    * Manage system resets from various commands.
    * Maintain parameter RAM (PRAM).
    * Manage the real-time clock.

    Important: Be very careful when handling the main logic board. Remove the battery when handling the logic board so the PMU is not affected. The PMU is very sensitive and touching the circuitry on the logic board can cause the PMU to stop responding. If the PMU stops responding, the battery life goes from about five years to about two days if the PMU is not reset. The PMU chip is located near the battery; refer to article 95035: "Power Mac G4 (AGP Graphics/Gigabit Ethernet): Logic Board Diagram" for the location of the PMU button.

    Many system problems can be resolved by resetting the PMU chip. Whenever you have a computer that fails to turn on, follow this procedure before replacing any modules.

    Resetting the PMU Chip Procedure

    1. Disconnect the power cord and check the battery in the battery holder (BT1). The battery should read 3.3 V to 3.7 V. If the battery is bad, replace the battery, wait ten seconds, and then reset the PMU (refer to the next step). If the battery is good, go to the next step.

    2. Press the PMU reset switch (S1) once on the logic board. Do not press the PMU reset switch a second time because it could stop the PMU chip from responding.

    3. Wait ten seconds before connecting the power cord and turning the computer on. If the computer turns on, go to the next step. If the computer does not turn on, there is something else wrong with the computer.

    4. Run MacTest Pro and return the computer to the customer.

    Note: This entire procedure resets the computer's PRAM. Be sure to reset the computer's time, date, and other system parameter settings before returning the computer to the customer.>

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