Mid-2011 iMac with No Power

[dbdjre0143]

Hi. Was hoping someone here may have some troubleshooting advice for a mid-2011 21.5 inch iMac.

When plugged in, the first diagnostic LED lights up, indicating that the trickle voltage from the PSU is working (which I also confirmed with a multimeter). Otherwise, there are no signs of life. Nothing happens when pressing the power button. This leads me to believe that one of three things isn't working correctly, the power button, the PSU, or the logic board. However, I don't really know how to narrow down the issue without just buying the parts and hoping I'm right the first try. Any thoughts on how to proceed? Thanks for your time!

 

[MBAir2010]

Reset pram, open in safe mode, unplug for 10 seconds, unconnected all usb devices.
Did you hear anything strange like a clinch noise while you used that iMac?

 

[dbdjre0143]

Reset pram, open in safe mode, unplug for 10 seconds, unconnected all usb devices.
Did you hear anything strange like a clinch noise while you used that iMac?

It's not mine, so I wasn't present when it started experiencing the issue.
Can't reset PRAM or open in safe mode because it literally does not respond to the power button (no drive noise, no fan movement, no second diagnostic LED lighting up).
It had been unplugged for multiple days when I opened it to start working on it last night, so unplugging isn't an issue.
Also, already have been trying with no USB devices.

Thanks for your help!

 

[MBAir2010]

Find out if you can hold a screw driver on the motherboard somewhere to jump start the imac, like we can with MacBooks.

 

[Guy Clark]

I would suggest removing the Logic Board and checking for popped capacitors
https://www.ifixit.com/Guide/iMac+Intel+21.5-Inch+EMC+2428+Logic+Board+Replacement/5959

If found there are two options. A replacement Logic Board which can be sourced for around $150 and would would be viable if the rest of the iMac is functioning correctly. The other option is to sell it for spares/repair.

I would go with a replacement Logic Board as the mid 2011 21.5" iMac is a fine machine. Purchasing a new Mac outright should be considered as a last resort as they are a challenge to service. I have a late 2015 21.5" 4k iMac and a mid 2011 21.5" iMac which I continue to use as my daily production machine.

 

[Fishrrman]

After 7 years, might be time to suggest to the owner that he/she start shopping for a replacement...?

 

[Guy Clark]

After 7 years, might be time to suggest to the owner that he/she start shopping for a replacement...?

Not necessarily if the remainder of the iMac is functioning correctly it is viable to replace the Logic Board if that is the issue. A refurbished replacement Logic Board can easily be sourced for around $150 or even less if you shop around which is considerably less than the value of the whole iMac.
The mid 2011 iMac range is worthy of considering repair as it has the outstanding Intel i5 Sandy Bridge Quad Core CPU which set new high standards for processing power
https://www.techradar.com/reviews/pc-mac/pc-components/processors/intel-core-i5-2500k-917570/review

 

[dbdjre0143]

I've priced around and found that I could get a PSU for <$35 and a logic board for <$100, so I'm going to talk to the person and see if they want to jump in. I'll likely replace the PSU first (gambling on the cheaper part), then if that doesn't work out, jump to the logic board.

After 7 years, might be time to suggest to the owner that he/she start shopping for a replacement...?

Haha, my personal Mac and daily driver laptop is still a Late 2005 Powerbook G4. This 2011 iMac is far from ready for the bin. (At least, not with the current price of parts. I realize that sometimes the cost of repair outweighs the cost of replacing the machine.)

 

[dbdjre0143]

Just wanted to post back with the final results of this:
The replacement PSU made no difference, so I ordered a logic board and its back in business. However two of the three fans were running full-blast all the time. I ended up downloading Macs Fan Control and, after confirming that nothing was actually getting too hot (temps were quite sane), using that to automatically manage the speed worked out fine.

 

[Guy Clark]

Just wanted to post back with the final results of this:
The replacement PSU made no difference, so I ordered a logic board and its back in business. However two of the three fans were running full-blast all the time. I ended up downloading Macs Fan Control and, after confirming that nothing was actually getting too hot (temps were quite sane), using that to automatically manage the speed worked out fine.

Glad to hear you got the issue sorted. Were you able to diagnose the fault with the Logic Board? One of the benefits of running an older iMac is they are almost entirely user serviceable.

 

[dbdjre0143]

Glad to hear you got the issue sorted. Were you able to diagnose the fault with the Logic Board? One of the benefits of running an older iMac is they are almost entirely user serviceable.

I did not diagnose the issue with the old logic board. (Got a great deal on the replacement though, $85!) I still have it though so may mess around and see if I can find any dead caps or something along that line. Anything much beyond that is outside my realm of capability.