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OS X Tip #82
Is your Mac not powering on or acting strange? Try this.
Resetting Your Mac’s Power Manager (PMU)
This is not really an OS X tip, but more of a Mac troubleshooting tip. Macs have a Power Manager chip (PMU) that controls power for your computer. Sometimes it can get corrupted especially after a power outage or surge. Strange things can happen to your Mac if this occurs, including not powering on, or not waking from sleep. On PowerBooks and iBooks, it can cause them to not even see power adaptors or fail to charge their batteries.
Resetting the PMU
May help resolve some of these issues. The procedure is a bit different for each Mac. Check these links to Apple’s documentation on how to reset the PMU for your model:
iMac G5 (Ambient Light Sensor), iMac G5 (iSight)
PowerMac G5
Xserve G5
Resetting your Mac’s PRAM and NVRAM
Resetting the PMU will cause your machine to loose the date and time settings. So you will have to reset your Mac’s clock after a reset.
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| Tags: mac tips, pmu, troubleshooting
