> > https://www.nytimes.com/2018/05/11/technology/personaltech/mac-smc.html > <https://www.nytimes.com/2018/05/11/technology/personaltech/mac-smc.html> > > The Keys That Might Fix Your Mac > > If your Mac greets you with a black screen, the fan runs constantly or you > notice other power-related issues, a simple home solution might save you a > trip to the Genius Bar. > > May 11, 2018 > TECH TIP > > Q. The other day, my Mac laptop would not turn on when I pressed the power > button, but a technician was able to get it to start by holding down a bunch > of keys. What is this fix? > > A. If a Mac does not respond to its power button after you have checked its > battery, connections and monitor, there might be a serious issue — but not > always. In this case, the computer’s original failure to react when you > pressed the power button was most likely a symptom of an issue with the > System Management Controller (S.M.C.), a microcontroller > <https://electronics.howstuffworks.com/microcontroller.htm> on the computer’s > logic board that handles various power, light and sensor functions for Macs > with Intel processors. > > Holding down the Shift, Control and Option keys while pressing down on the > power button (or Touch ID button <https://support.apple.com/en-us/HT207054>) > for at least 10 seconds is a shortcut for resetting the S.M.C. on MacBooks > with sealed batteries. If this was the case, the laptop starts up normally > again when you press the power button again. > > > If you have tried Apple's other troubleshooting steps and nothing works, > press the Shift, Control, Option and Power keys (all highlighted) for at > least 10 seconds to reset the Mac's System Management Controller.The New York > Times > An S.M.C. reset may help if you notice things like the battery is not > charging properly, the Mac does not recognize devices plugged into its USB-C > port, the keyboard backlight is not working correctly or the sleep function > is out of whack. Other symptoms include the computer fan’s running at high > speed or the Mac’s acting sluggish, even if you are not using a lot of > processor-hogging programs. > > Apple’s support site has a full guide to the S.M.C. reset process > <https://support.apple.com/en-us/HT201295> for all its Intel-based Macs, > including those with removable batteries and desktop models. The guide also > lists a series of things you should try before resetting the S.M.C. While > performing a reset does not generate an alert box or notification, you can > tell if you were successful if the odd Mac behavior stops. (You may also have > to redo any preferences for your display and power-management settings.) > > Resetting the S.M.C. might fix erratic Mac behavior, although it will not > help with a damaged power supply or another major hardware problem. > > Modern Macs also store some settings in an area of the system called the > nonvolatile random access memory (NVRAM); older Macs use parameter > random-access memory (PRAM) in a similar manner. If the Mac is not > maintaining its settings for volume level, display resolution, time-zone > information or preferred start-up disk, information held in the NVRAM may > have become corrupt. > > You can reset the NVRAM <https://support.apple.com/en-us/HT204063> or PRAM by > shutting down the Mac and then starting it up again while holding down the > Option, Command, P and R keys all at once. When you hear the second start-up > tone <https://support.apple.com/en-us/HT202768> (or, on a Mac Pro, see a > second Apple logo appear and disappear), you can release the keys and let the > computer finish its start-up sequence. > > Personal Tech invites questions about computer-based technology to > tech...@nytimes.com <mailto:tech...@nytimes.com>. This column will answer > questions of general interest, but letters cannot be answered individually. > > J.D. Biersdorfer has been answering technology questions — in print, on the > web, in audio and in video — since 1998. She also writes the Sunday Book > Review’s “Applied Reading” column on ebooks and literary apps, among other > things.@jdbiersdorfer <https://twitter.com/jdbiersdorfer>
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