3 - I have another identical computer. Is it safe to remove the power supply from that iMac and put it into my wife's iMac, to see if it works?Safe, if your hands are straight.
3 - I have another identical computer. Is it safe to remove the power supply from that iMac and put it into my wife's iMac, to see if it works?Many thanks...
If its completely dead it may be something quite simple...That was exactly my thinking.
...before you start doing things, since you have another computer, you should try to find the Apple repair docs on that particular model, If you are certain you both have the same machine, look in your "about this Macintosh" The model name should be there...I do have the exact same machine but can't find Apple repair docs in "about this Mac". I also looked a bit online (even before I posted here) but not found the resource, as of yet. I'll look some more.
Try the repair manuals resources listed here in the wiki...I didn't know there was a wiki here... I'll look.
I would NOT at this stage put your other power supply in this machine...That's why I asked. For future reference, is is possible there is something else wrong, which killed the power supply, and I risk killing another power supply with such test?
Yeah, completely dead and silence, most likely is the primary greenchip, mosfet and fuse...I was also thinking that if it was just faulty caps I'd still be seeing/hearing some activity.
the iMac 27 has 4 leds, located at the right of the ram slots...Thanks for this information. After some Googling I found these are called diagnostic LEDs and are on the logic board and I need to remove the screen again to see them, correct? I can't see them through the vent holes at the bottom, so the screen needs to be off. I'll do this tonight.
...you should locate these leds while it works, because they are not obvious, specially when off ...
again, I'm pretty sure now that this is a graphic card failure, like almost of these 2011 imacs. get another one while there are available (and claim by apple because it's a known problem, and it will cost you some $500...) you can find them also on ebay for a not so lower price.We plan to keep both iMacs for quite some time so perhaps it would be good to grab one graphics card, even if this problem turns out to be something else, just to have a "spare tire".
you could also have been in front of a power supply security state, then you must unplug the cord, press the power button for 10s, then wait 10s and plug it again to reset to normal state. it's sometimes simple as this. ( and you can see it with the 1st led is on)I couldn't find any Google results for "iMac power supply security state" but I can understand what you meant. If or when it happens again I'll try this procedure to rule out.
When I go to "About this Mac > Hardware > Graphics/Displays" it says "Chipset Model: AMD Radeon HD 6970M". This is the part and model number I should be looking for, right?yes ... and no, as it is a model specific to the imac 27", you cannot grab any card with that reference
Questions:no, there are no upgrade to these models, although there is a 1Gb and a 2Gb model that fits in these imacs.
1 - Is there perhaps another compatible model that is an upgrade and perhaps does not have the same known problem?
2 - I see some on eBay, most without a heatsink. Any reason why I should avoid buying one without the heatsink?you don't need the heatsink as it is already inside your imacs. but it's a little easier to change if it is already mounted.
3 - Lastly, most that are offered for sale will be used and I guess chances are they had the same problem and they just stuck them in the oven to reflow the solder. Is there any way of knowing if the solder has been reflown?no method I'm aware off to know that . sorry.
We plan to keep both iMacs for quite some time so perhaps it would be good to grab one graphics card, even if this problem turns out to be something else, just to have a "spare tire".
Nov 18 12:38:31 Partenze webfilterproxyd[1404]: isAppleURLString - checking: r5---sn-ab5szn7y.googlevideo.com
Nov 18 12:38:31 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - checking: r5---sn-ab5szn7y.googlevideo.com
Nov 18 12:38:31 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - returning NO
Nov 18 12:38:31 Partenze parentalcontrolsd[1581]: contentFilterPageWasVisited:address: entered
Nov 18 12:38:32 Partenze firefox[259]: CVCGDisplayLink::setCurrentDisplay didn't find a valid display - falling back to 60Hz
Nov 18 12:38:32 Partenze webfilterproxyd[1404]: isAppleURLString - checking: i.ytimg.com
Nov 18 12:38:32 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - checking: i.ytimg.com
Nov 18 12:38:32 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - returning NO
Nov 18 12:38:32 Partenze parentalcontrolsd[1581]: contentFilterPageWasVisited:address: entered
Nov 18 12:38:32 Partenze webfilterproxyd[1404]: isAppleURLString - checking: i.ytimg.com
Nov 18 12:38:32 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - checking: i.ytimg.com
Nov 18 12:38:32 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - returning NO
Nov 18 12:38:32 Partenze parentalcontrolsd[1581]: contentFilterPageWasVisited:address: entered
Nov 18 12:38:33 Partenze firefox[259]: CVCGDisplayLink::setCurrentDisplay didn't find a valid display - falling back to 60Hz
Nov 18 12:38:34 --- last message repeated 3 times ---
Nov 18 12:38:34 Partenze webfilterproxyd[1404]: isAppleURLString - checking: r5---sn-ab5szn7y.googlevideo.com
Nov 18 12:38:34 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - checking: r5---sn-ab5szn7y.googlevideo.com
Nov 18 12:38:34 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - returning NO
Nov 18 12:38:34 Partenze parentalcontrolsd[1581]: contentFilterPageWasVisited:address: entered
Nov 18 12:38:35 Partenze firefox[259]: CVCGDisplayLink::setCurrentDisplay didn't find a valid display - falling back to 60Hz
Nov 18 12:38:39 --- last message repeated 6 times --- Nov 18 12:38:39 Partenze webfilterproxyd[1404]: isAppleURLString - checking: i.ytimg.com
Nov 18 12:38:39 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - checking: i.ytimg.com
Nov 18 12:38:39 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - returning NO
Nov 18 12:38:39 Partenze parentalcontrolsd[1581]: contentFilterPageWasVisited:address: entered
Nov 18 12:38:39 Partenze webfilterproxyd[1404]: isAppleURLString - checking: i.ytimg.com
Nov 18 12:38:39 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - checking: i.ytimg.com
Nov 18 12:38:39 Partenze webfilterproxyd[1404]: isAllowedAuthURLString - returning NO
Nov 18 12:38:39 Partenze parentalcontrolsd[1581]: contentFilterPageWasVisited:address: entered
Nov 18 12:38:39 Partenze firefox[259]: CVCGDisplayLink::setCurrentDisplay didn't find a valid display - falling back to 60Hz
Nov 19 20:54:07 localhost bootlog[0]: BOOT_TIME 1511142847 0
...If your graphics card isn't clearly at fault, its dumb to buy another one.After I saw how much these graphics cards go for I came to the conclusion that for about $300 more I can just buy an entire used iMac, an identical one, and if it works out then keep the current Mac for spare parts. And it sure beats paying Apple service a few hundred dollars to see if they'll be able to fix anything, or to tell me that for a few hundred more they might be able to fix some more.
the iMac 27 has 4 leds, located at the right of the ram slots,
with a power cord pluged in, you should see one led on, meaning the trickle power is here, so the power supply is good.
the second one lights up when you press the power button, the 4th is when the cpu communicates with the graphic card.
this is the test to do when the mac does not power on.
you should locate these leds while it works, because they are not obvious, specially when off ...
You need to know what the Apple docs say for your unit!Louis did a lot of laptops macbookpro's, but quite no iMacs (I've not found any ?) , and no iMacs graphics cards
Also, look at Louis Rossmann's videos - maybe search on "iMac"?
Did you reset the PRAM? (you know, basic Mac stuff)
that your CPU has difficulties to communicate with the graphic card, so again, the graphic card must be dying.the iMac 27 has 4 leds, located at the right of the ram slots,
with a power cord pluged in, you should see one led on, meaning the trickle power is here, so the power supply is good.
the second one lights up when you press the power button, the 4th is when the cpu communicates with the graphic card.
this is the test to do when the mac does not power on.
you should locate these leds while it works, because they are not obvious, specially when off ...
OK, now I just completed the test with the screen removed, observing the diagnostic LEDs.
The 1st LED turned on when I plugged the power chord.
The 2nd LED turned on at the moment I pressed the power button.
The 3rd LED turned on when I heard the booting sound, then half a minute later the fans started spinning
The 4th LED did not light up after a few minutes, so I held the power button for a few seconds, the computer shut off and the only LED left on is the 1st one.
What conclusion can we draw from this test?
Thanks...
...What about other logs? There are lots of logs..
...power supplies gets bad quite only with overvoltage on mains.That computer is plugged into a heavy duty line conditioner, so there should be no spikes or line noise hitting the Mac's power supply. The only other units plugged into that same line conditioner are 2 external hard drives.
Repairing mac's... :horse:is easier than you think ...
quote]
Looking at the logs is something new to me and I am doing a lot of Googling to get info on how to do this (I want to be respectful of everyone's time and don't want to bother anyone here to spoon feed me, step-by-step).
But just so that I clearly understand what you mean... When you ask about the other logs, are you referring to other logs in that same log file, or other logs that are stored in other files?
I copied the above logs from a file "var/log/system.log". Every day the Mac stores a fresh "system.log" file in that directory. I used Console to access that and I can see there are dozens of other log files and directories that I can access. Some are clearly specific to some applications and some are labeled with names that are impossible to interpret without Googling.
...my Mac laptop, like me, are so old we basically are still living in the past.
You're not alone. I still sometimes boot my old Mac PowerBook G4 laptop, as it has some applications that never got updated and are the only applications that can open certain files that I occasionally have to open.you can use a free program called "sheepshaver" that will let you have a mac os 9 virtual machine in your actuel mac