Q: Is there a list of "APPROVED REPLACEMENT HDD" for the 21.5 late 2009 iMac that has the built in temperature sensor?
iMac EMC 2308
Apple OEM HDD - Barracuda 7200.12 1000Gb
ST31000528AS
P/N: 9SL154-040
FIRMWARE: AP24
DATE CODE: 10124
APPLE P/N: 655-156A
REPLACED WITH - BarracudaLP 2TB 32MB INTERNAL KIT 5900
ST320005N4A1AS-RK
P/N: 9JB1AT-573
BACKGROUND
After 13months of ownership I started to notice significant system slow downs and what appeared to be pauses (spinning pizza cutter) as the OS accessed the HDD. I performed a "Disk Verify" using Disk Utilities and received the S.M.A.R.T Drive Failure detected, Backup your data and replace HDD. I replaced my OEM 1TB HDD with a 2TB model following the replacement instructions at iFixit. The step-by-step guide was flawless, until I re-started the iMac. After approx. 2-3 min the HDD Fan began to increase in speed from ~1100rpm to ~5100rpm (over a 10 min period).
Right now iStat is reporting 5127rpm and HD temp of 108degF
I've performed all the easy stuff ... SMC Reset ... PRAM Reset ... verified Temperature connector was reinstalled as removed etc.
There does not seem to be a definitive solution/fix on any of the other "solutions pages".
1. Other sites suggest that the cause is in the proprietary firmware (AP24) that Apple uses on it's HDD to control the temp. Is this true? If so how do you get a copy?
2. Has anyone tried replacing the Thermal connector that plugs into the drive with the older "stick on" thermal sensor? If so does it work?
I was all set to buy a new HDD from Apple, but when the "tech" at the "Genius Bar" looked up the price -- $506. His first response was ... "WOW that is the most expensive HDD I've ever seen, even by Apple Standards."
tech-Do you know how to use a screw driver?
me-YES
tech-Then do it yourself, it's very easy, use the instructions at iFixit.
me-are there any limitations?
tech-just buy the same kind of drive...you have a seagate, so just go to BestBuy and pay $100 bucks, and you can even upgrade to a 2or3TB.
Thanks for the help
iMac, Mac OS X (10.6.7), EMC-2308
Posted on Jun 9, 2011 1:37 PM
Thanks Roger. I'll contact OWC
It sounds like the only current solution is to replace the HDD thermal sensor connection with the older external Thermal Sensor that sticks to the outside of the drive. I also found this recommendation from another post confirming this.
THANKS TO ALL WHO RESPONDED I HOPE OTHERS WHO DARE TO VENTURE INSIDE THEIR iMACs FIND THIS HELPFUL
As mentioned above, installing a replacement hard drive does not allow the HD temperature sensor to work correctly. The original Apple drive has a unique firmware that allows the factory sensor connector to work as the logic board expects. Any drive without Apple firmware will not feed the temperature info to the motherboard and the internal fan speed will eventually crank up to its max RPM. Even installing a new drive that matches the brand of the original factory drive will not stop this from happening. I tried putting a Seagate 7200.xx drive in place of the original 7200.xx drive and the fan still went full tilt boogie.
So, I decided to buy an optical drive sensor (Apple part #922-9141) and use that in place of the original HD sensor. It plugs into the logic board where the old HD sensor did and sticks to the hard drive with an adhesive that is already on the sensor. After installing this and reassembling the computer, the system's fan behavior was normal.
A VERY important detail regarding disassembly of the computer...
Before you lift the LCD panel out of the system, it is critical that you ONLY lift the display panel a few inches at the top edge. Then, you need to gingerly undo the small ribbon cable (that is for display sync), which is located in the upper left corner of the computer:
I specifically call out this part of the process, because this cable is very fragile. It's a horrendous design where the contacts are essentially copper leaf glues onto a thin piece of plastic. If the connection is pulled at the wrong angle, or perhaps even inserted/removed too many times, the copper will separate from the backing. And I suspect that this cable is not easily replaced, as it appears to be hard-wired to the display panel.
The service instructions at a popular fixit site show the removal of the LCD panel, in order to replace the hard drive. I did not find this to be necessary. After disconnecting the aforementioned sync cable connector and perhaps one other, I was able to simply prop up the top of the display panel to a sufficient height ( about 8 inches) to allow full access to the HD. I propped the display with an inverted plastic DVD-R spindle (saved after I used up the 100 discs). I did this in order to avoid disconnecting any connectors that I didn’t have to. I was worried about the fragility of the other connectors and felt it was best to avoid pulling apart anything that I didn’t have to. You may want to do the same.
Chris Hart, Independent Mac Computer Consultant in Connecticut, Mac OS X (10.6.4)
Message was edited by: dMac16
Posted on Jun 10, 2011 4:52 AM