Hello Ronni Thanks for the suggestions.
> I guess you have tried SMC reset on your iMac - restart unplug power line for > 30 seconds, (reset SMC). Yes! But it seemed to take many minutes to power-up, as if some thermal cut-out had operated and had to cool down first. > Have you run the Hardware Test? > Could be a faulty 'Power unit’ or Logic board. I ran AHT in both standard and extended test modes this afternoon. No problems found. Mac had been turned off since last night, so tests were done with a cold machine. It was good to notice that cooling fans seemed to operate from time to time during the memory and logic board tests. So my problem is not with failure of the fans themselves. This Mac is normally silent and cool in operation, so now I know what the fans sound like. AHT did not display a separate sequence for a “power unit” test. So the power unit remains under a cloud - the old leaky capacitor syndrome?? > Require more information as to what you mean by “Mac Failed”? > What happens… does it just shutdown when you are working in a particular > program or does the iMac shut down randomly with no apparent reason? “Mac failed” seemed to be a total internal disconnection from mains power. Data light on attached USB hard drive was not operating. iMac would not start up straight away by pressing the power button after it had shut down. I removed power cable and changed power points which would give enough time for SMC reset. Program running during the first shut down event (Friday) was EyeTV. It was writing a 50 minute HD video to an internal folder (say a 30 minute process) so I was not sitting at the computer at the time. iMac must have shut down just after the processing was completed. Program running during the second shut down (Saturday) was iTunes - shut down happened just a few minutes after the start of the AppleTV video playback. iTunes library is located on an external USB hard drive. Looks like random events rather than a specific program. > iStat Menus help control the speed of fans in your Mac. This app would seem to be useful for Macs that are running hot or have fans continuously running. As my iMac is normally silent, the auto fan speed must be very low. Perhaps iStat Menu would be more useful than Activity Monitor which I find slow to display data if there is a CPU load issue. I will look into this app later. In conclusion I think I will need to monitor operations and carefully note conditions while in use and when it fails. Cheers Alan (Late 2012 iMac 27" Intel Quad Core i5 Fusion 3.2GHz 8G RAM - OSX 10.11.3 El Capitan) > On 11 Dec 2016, at 2:04 PM, Ronni Brown <[email protected]> wrote: > > > >> On 10 Dec. 2016, at 8:57 pm, Alan Smith <[email protected] >> <mailto:[email protected]>> wrote: >> >> How can I find readings (and adjust) the fan speed of my late 2012 27inch >> fusion drive iMac? Is there data log of fan history? >> >> Mac failed yesterday and today. Restarted OK after say 20 minutes after >> trying different power point, cable, etc. Mac case was cool to touch but I >> don't recall any fan sound at all. > > Hello Alan, > > Require more information as to what you mean by “Mac Failed”? > What happens… does it just shutdown when you are working in a particular > program or does the iMac shut down randomly with no apparent reason? > > I guess you have tried SMC reset on your iMac - restart unplug power line for > 30 seconds, (reset SMC). > > Have you run the Hardware Test? > Could be a faulty 'Power unit’ or Logic board. > > If it came with Lion or later, follow these instructions: > Carefully read and follow the instructions, running AHT on a 2012 iMac is > pretty straightforward. > <http://support.apple.com/kb/HT1509 <http://support.apple.com/kb/HT1509>> > > 1. Turn off the iMac and then start it again while holding down D > > > I find iStat Menus very useful monitor. iStat Menus lets you monitor your > system right from the menubar. > Included are 8 menu extras that let you monitor every aspect of your system. > iStat Menus 5.31 > > iStat Menus help control the speed of fans in your Mac. > NOTE: that fans are always controlled by the System Management Controller > (SMC) in your Mac — iStat Menus simply asks the system to increase the lowest > fan speed. > It can’t lower fans below the speed the SMC would normally use. > > https://bjango.com/mac/istatmenus/ <https://bjango.com/mac/istatmenus/> > > Cheers, > Ronni > > 13-inch MacBook Air (April 2014) > 1.7GHz Dual-Core Intel Core i7, Turbo Boost to 3.3GHz > 8GB 1600MHz LPDDR3 SDRAM > 512GB PCIe-based Flash Storage > > macOS Sierra 10.12.1 > >> >> Regards >> Alan Smith >> >> Sent from my iPad > > > > -- The WA Macintosh User Group Mailing List -- > Archives - <http://www.wamug.org.au/mailinglist/archives.shtml> > Guidelines - <http://www.wamug.org.au/mailinglist/guidelines.shtml> > Settings & Unsubscribe - > <http://lists.wamug.org.au/listinfo/wamug.org.au-wamug>
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