Only the first diagnostic led is on when connected to power. Nothing happens when i press the button.

Does this mean my logic board is broken? Cause replacing that is way to expensive.. :(

⟐ Commented Ağustos 20, 2024 at 19:40 GMT-7

⟐ Commented Mart 26, 2024 at 14:55 GMT-7

I need to be 100% sure that if the information it's correct. I want to place a PCIe SSD blade to my Imac but I would like to know if any of the below options works for my IMac, if you agree with the following information please let me know:

1) Apple SM0512F or SM0256F SSD PCIe blades are the same Samsung blades models MZ JPU512T/OA6 (512GB) and MZ JPU256T/OA6 (256GB) respectively.

2) Those blades are used and compatible with the following models:

• MacBook Pro (Retina, 13-inch, Late 2013)
• MacBook Pro (Retina, 13-inch, Mid 2014)
• MacBook Pro (Retina, 15-inch, Late 2013)
• MacBook Pro (Retina, 15-inch, Mid 2014)
• MacBook Air (11-inch, Mid 2013)
• MacBook Air (11-inch, Early 2014)
• MacBook Air (13-inch, Mid 2013)
• MacBook Air (13-inch, Early 2014)
• iMac (21.5-inch, Late 2013)
• iMac (27-inch, Late 2013)
• iMac (Retina 5K, 27-inch, Late 2014)
• Mac Pro (Late 2013)
• Mac mini (Late 2014)

Am I right?

If yes, these blades would work for IMac 21,5" and 27" Late 2013 and 2014.

I just need to be sure before I buy some used pulled from a Mac lap-top

⟐ Commented Mart 07, 2021 at 19:00 GMT-7

⟐ Commented Temmuz 29, 2025 at 22:06 GMT-7

⟐ Answered Haziran 20, 2025 at 12:11 GMT-7

⟐ Commented Ağustos 31, 2022 at 18:46 GMT-7

I have an iMac 2009, 21,5" which has been working well until last week. First there was some flickering and sometimes a black display. Since yesterday the display seems not to work anymore.

I have found the apple technicians guide for this iMac online and tried some of the solutions described there. I did a SMC/PVRAM Reset, but this did not solve the problem.

To determine if it's the gpu I connected an external monitor -> everyhing working fine on the external monitor.

It seems that the LED backlight isn't working anymore, because if you use a flashlight you can see everything on the internal screen.

I asked at a local repair store but they told me (without looking at the device...) that it was either the LCD panel, which would cost almost 500€/650$ to replace or the SATA/Board (Logic board?) which would even be more expensive.

My question is whether it's possible to determine if it is the logic board, ta cable connection, the Backlight controller or the LCD-Panel.

Thanks fpr your answers,

Max

⟐ Commented Nisan 03, 2024 at 2:13 GMT-7

I have an early 2009 24" iMac. It works well but it's starting to get old.

My question is if there is a chance to use it as an external monitor attaching a LCD controller to the screen.

My goal is to make a switch to use the iternal hard (core2duo) or use the imac as external monitor with a DVI plug on the back.

Thanks.

⟐ Commented Ocak 31, 2026 at 14:59 GMT-7

⟐ Answered Mart 30, 2020 at 1:49 GMT-7

⟐ Answer edited Eylül 17, 2025 at 8:59 GMT-7

⟐ Commented Nisan 06, 2019 at 9:02 GMT-7

First part: 970 EVO NVMe with heatsink installed. Recognized @ Link x4 and great speed. SSD installed and MacOS Catalina reinstalled. Very happy so far.

Second part, a day after: Removed CPU, installed i7-7700k. Struggled a bit with heatsink like everyone it seems. But once done I felt confident that everything was done right, so I re-assembled everything. But the power switch didn't trigger anything!

• LED 1 is on as soon as I connect the iMac to the external power cord.
• Power switch cable seems intact and connected to PSU. PSU and logic board cables all disconnected/reconnected with great care and seem intact.
• Tried to short both power switch pin to start up the Mac. Nothing happened.

Does anyone have any suggestions or comments on what the problem may be?

• I've ordered a new PSU for safe measure. I can't find a spare power switch button (the only part available that has it is an entire empty housing!).
• Can't find a spare power supply control cable (between PSU and Logic board) for a 2017 iMac. But there are some for the 2011-2013 iMac which looks the same as for the 2017 version.
  

Tempted to order that. Does anyone know if the 2013 and 2017 use the same power control cable?

After discussing with friends, one plausible explanation could be that my CPU upgrade went bad. Such as static electricity frying the Logic board. Or the CPU is bad. Even though I've been careful all the way. However, if I understand the explanations regarding the logic board LEDs function, it seems that not even having the LED 2 or 3 on would mean my issue isn't yet entirely related to the Logic board or the CPU. Anyone can comment on this?

I would be very grateful for any suggestions (at least it'll boost my morale, as right now if the new PSU doesn't work, I would have probably to sell the iMac for parts!!)

Thanks

Seb

Just received the new PSU (see picture). Installed carefully (making sure I discharge any static electricity from my hands prior). Reconnected all wires, after inspecting them (see picture). And unfortunately I have the same result: the power switch, which seems to be 100% intact (see pictures), doesn’t trigger any response. Fan doesn’t spin. No second LED.

Could it be the main power cable socket (buried under the bottom bezel of the imac housing)??

Any suggestions welcomed!

Disassembled the Mac again. Look very carefully for damaged cables, or sockets… None found! Took a picture of the wires coming from the main power socket (see below). Everything looks fully functional.

Could this be a back Logic Board??

I can finally breath: Removed the new CPU, installed the old CPU and I’ve got the board to boot up. Did not perform a full reboot with the LCD on. I will make another attempt at upgrading tomorrow with another CPU, so I had only the PSU and Logic board mounted.

Is this a Bad CPU or it wasn’t mounted right, I can’t say for sure. But the Fan started to spin at max speed without stopping, so that got me thinking and decided to go for the i7-7700 instead of the 7700k!

Now, I got to improve my tension spring loading technique. I concur with others that the tension produced by this spring is excessive (Judging from the residue of thermal paste which had been completely squeezed out to the sides when I removed the CPU). So I’ve kept a more important gap between the mounting spring and the logic board, than what I had originally measured (<1mm). See pictures.

Hopefully my next post will be about completing this job… Wish me luck.

Final update: Finally got the system to work.

How: The short answer is you have to unbend the metal spring underneath the CPU!

There is way too much tension in this spring, this put so much strain on the CPU that it bends it. Some pins are then no longer connected. When the LED 1 or 1-2 lit up and nothing more it just means that.

I’ve tried a i7-7700k twice, reinstalled the i5-7600, then tried and kept a i7-7700 finally. So I’ve got plenty of trials to figure all this out.

I will now answer questions :)

⟐ Commented Temmuz 15, 2025 at 10:24 GMT-7

By now I have made a try, putting physically close, in the 4 available trays, similar modules (4GB with 4GB, 8GB with 8GB).

This is the configuration I got from system info (RAM modules coupled in the same bank)

BANK0/DIMM0 8GB

BANK1/DIMM0 4GB

BANK0/DIMM1 8GB

BANK1/DIMM1 4GB

Is this correct, or should I insert them physically alternated, so they I have the same modules coupled in the same DIMM?

Thanks for your help

Francesco

⟐ Commented Mayıs 06, 2025 at 15:21 GMT-7

I have two iMac 27's. One has an an Intel Core i7 processor.

The other one has an Intel Core i5 processor.

The speed difference is noticeable, so I'd like to upgrade the i5 to an i7 processor. Can someone please give me the i7 processor model number?

Can it be swapped plug & play, with no other concerns?

⟐ Commented Ekim 03, 2024 at 9:19 GMT-7

⟐ Commented Nisan 25, 2021 at 20:07 GMT-7

⟐ Commented Aralık 27, 2020 at 3:12 GMT-7

I performed the Dual Hard Drive Kit upgrade as suggested in the guide at Installing iMac Intel 27" EMC 2429 Dual Drive Kit (HDD or SSD)

I followed the steps precisely during the whole process.

After the second drive (SSD) was installed, I booted up the iMac and heard loud fan noise after a few seconds. Both CPU and ODD fans are running at full speed.

I have tried resetting SMC/PRAM, but to no avail. I reassembled the logic board twice, with and without the Dual Drive Kit upgrade. It still didn't fix the problem.

So, I believe something somewhere has gone wrong and I need to identify the problem and fix it.

I have also noticed that it is not just the fans that are loud, my game which I play every day at 30fps, is crawling at 6-7fps after the upgrade (still utilizing the HDD though, not the SSD).

Running the Apple Hardware Test revealed failure with TA0P code, which indicates Ambient Temperature sensor/connector failure according to some google search results.

Moreover, Temperature Gauge Pro app reports the following:

ODD 3729 RPM

HDD 1097 RPM

CPU 3917 RPM

Fan Diagnostics: These fans appear to be not working properly : ODD

Sensor Diagnostics: These sensors appear to be not working properly : CPU

Some further Googling has revealed that this person had a similar problem and flipping the LCD Thermal Sensor Cable fixed it for him: http://forums.macrumors.com/showpost.php...

However, I'm not sure which of the cables mentioned in the iFixit guide are the LCD Thermal Sensor Cable, for me to give it a go (I doubt any of the cables can be flipped on this model though).

Any help would be appreciated.

TLDR:

• After installing 2nd drive (SSD) on 2011 27'' iMac,
• CPU and ODD fans are running at full speed, HDD fan at normal.
• Degraded gaming performance at 6-7fps.
• Failure in Apple Hardware Test with code TA0p.
• Something somewhere went wrong in assembling/disassembling (perhaps).

Thanks!

I removed the LCD panel from the iMac and booted it with external Cinema Display. The fans are still loud. So I doubt that the problem is with LCD sensor. Maybe I should pay attention to the Ambient Sensor/connector, since the AHT failure also reported a fault with that.

⟐ Commented Eylül 24, 2020 at 12:39 GMT-7

After taking it off again I noticed I had broken it. So I went to Amazon and bought a new one for $26.

However I can't figure out how to place the connector in and I don't want to break it again. Please help

Damaged one:

http://m.imgur.com/a5TsmDL

New one:

http://m.imgur.com/hEmOw7U

And...

http://m.imgur.com/i5qvX2U

http://m.imgur.com/mwICz0Z

⟐ Commented Mayıs 21, 2022 at 9:54 GMT-7

I did every trick I could find on the web and nothing.

Took it to apple genius bar, my warranty had just expired in may...they tried new power supply and nothing. New logic board, nothing again...so they called corporate and they told them its a "cascading" issue, meaning the power supply/logic board and even the back casing had to be replaced. Anybody even heard of this? it would cost me $1000 to fix it. anybody had the same problem?

⟐ Commented Şubat 23, 2021 at 21:24 GMT-7

⟐ Commented Mayıs 15, 2020 at 16:28 GMT-7