iFixit - Answers With Device "iMac"

iMac G3 Model M5521: iMac G3 Slot-Loader chimes, then turns off.

Tue, 19 May 2026 03:45:44 -0700

Back in January I got this iMac G3 for pretty cheap. It originally powered on but showed nothing on the CRT.

When I connected an external VGA monitor, I saw it did boot to the “No boot device” screen, which was expected since the original HDD was removed due to failure.

Eventually a MacOS install CD got stuck, so I opened it up and removed it manually. After that, the behavior changed. It now chimes with the green power LED, then as the external monitor briefly detects a signal, it shuts off.

If I try again right after, the power LED comes on but nothing else happens. No chime, no video, nothing until I power it off manually. After unplugging for a few seconds and plugging back in, it goes back to the initial state where it chimes and then shuts off when it should show video on both CRT and external display.

What can I do? I replaced the PRAM battery and it made no difference. It also shuts off before I can do a PRAM reset (Opt+Cmd+P+R), and the physical PRAM button hasn’t helped either.

Trickle voltages seem normal, but when it reaches the “power LED only” state, the down-converter board trickle voltages are lower than normal.

I can also hear the high-voltage crackling as it powers off, so I assume the CRT is receiving power in some way. One other thing of note is that either the speakers, or the down converter board make a high pitched sound, I'll attempt to identify the source later today.

⟐ Commented Mai 19, 2026 at 3:45 GMT-7

iMac Intel 20": Wifi says it's connected but the internet

Mon, 11 May 2026 07:45:53 -0700

The wif says it's connected to the router but the internet doesn't work

⟐ Commented Mai 11, 2026 at 7:45 GMT-7

iMac Intel 27" EMC 2390: planning to upgrade my 10 years old iMac, help in choosing the parts!

Thu, 07 May 2026 22:33:43 -0700

Hi,,

I am planning to upgrade my iMac (27 inch - mid2010) which is now 10 years old and running on El Capitan 10.11.6 OS. Since its having a good CPU (i7 2.93) I am considering replacing the stock HDD (1TB) to an SSD, and maximising the RAM from 8GB to 32GB.

is this upgrade worth it? and will I notice a different when using it?
for the RAM upgrade, I think this part is the best option (iMac Intel 27" (Core i5 or i7) EMC 2390 (Mid 2010) Memory Maxxer RAM Upgrade Kit)?
for the SSD, I was reviewing this guide (Mac Intel 27" EMC 2390 Hard Drive Replacement), and I am confused about the parts options. the SSD Upgrade Bundle with Crucial MX500 SSD 1TB, or buying 2 TB SSD Segate Hybrid 3.5" Hard Drive with all the required tools separately which will almost cost the same. my concerns are:
- is the two SSD mentioned having the same performance?
- is the two SSD mentioned having the same certification with my iMac?
- is there any drawback for using Segate 2TB over Crucial 1TB?

This is my first time upgrading my iMac, and I really appreciate if you can guide me in selecting the best parts to get the most performance out of it for the longest period.

Regards,

⟐ Answered Mai 07, 2026 at 22:33 GMT-7

iMac Intel 27" Retina 5K Display 2020: SDD ribbon cable replacement

Sat, 02 May 2026 11:48:43 -0700

I have a bare 820-01779-A logic board and am trying to identify a small ribbon cable connector on the screen-facing side of the board. There are no SATA connectors on the heatsink side as seen on 2019 boards. Can anyone identify what this ribbon connector is and whether it has any relation to SATA storage?

⟐ Answered Mai 02, 2026 at 11:48 GMT-7

iMac M1 24": Horizontal lines over iMac 24 screen

Sat, 02 May 2026 00:54:57 -0700

Hi,

I got horizontal lines over the display! During the warranty period they replaced the board ( it blacked out ) and now this is happening. They refused to replace the device saying out of warranty and asked to replace it :-|. They were not even sure that changing the display will fix the issue. I am hesitant to replace the screen as I am better off to buy a new one rather keep repairing the faulty product.

Is there any way to fix it?

Tried
- Reinstall the OS
- External Display = Works fine
- Reseating those 3 cables

Lines kind of flickers, may be some lose cables?

Please help

⟐ Commented Mai 02, 2026 at 0:54 GMT-7

iMac: Testing motherboard with no display?

Fri, 01 May 2026 15:24:55 -0700

I've got several 27" iMac motherboards. I have at least 2 that power up and have the startup sound, however I don't have a working LCD. I have two external monitors and I have a display port to DVI cable but when I connect up the external monitor all I get is either a black screen or a "check signal" message.

What am I missing? I thought the display port should function regardless of the presence of the LCD panel or GPU?

⟐ Commented Mai 01, 2026 at 15:24 GMT-7

iMac Intel 27" Retina 5k Display: Is Velcro or 3M Dual Lock a good substitute for display adhesive?

Sun, 26 Apr 2026 19:06:35 -0700

I have an early 2015 iMac with a fusion drive setup where the SSD expired. I plan to replace it with an SSD and use the hard drive from the configuration in an external enclosure. This is an aging system, though, and at some point I plan to convert the iMac into a monitor, so I'd like to be able to access to the internals without buying another set of adhesive strips. I saw a guide on using magnets for this, but it doesn't include any good way to attach the bottom of the screen. I'd like to know if 3M Dual Lock (a stronger Velcro substitute) is a viable alternative to the adhesive, and if so, how much do I need of it to hold the screen on well?

⟐ Commented April 26, 2026 at 19:06 GMT-7

iMac Intel: Lots of old parts - what to do with them?

Sat, 25 Apr 2026 05:55:47 -0700

I have several 27" iMacs in various states of disrepair as a result of repeatedly breaking the LCD on mine. What can I do with the parts?

Ideally I'd love to sell them for whatever I can get cause times are hard right? What can I do besides recycle them?

I have parts for 4 complete 27" 2015 iMacs including cases, power supplies, mother boards, speakers, fans, stands, etc....

Most of the electrical components either dont work or I have no way of testing them. I just want to get them off my desk at this point.

⟐ Answered April 25, 2026 at 5:55 GMT-7

iMac Intel 27" Retina 5K Display 2019: Microphone is broken after upgrading ssd

Mon, 20 Apr 2026 15:15:48 -0700

Any idea where i can get that part?

the ribbon is so fragile, looks like it broke

thanks

After changing the microphone for a new one it is still the same problem, no idea what happened, i was being very careful inserting the flex cable on the board.. when removing the original one i pulled it instead of removing the tiny latch because i did not know

Any idea?

Thanks

⟐ Answer accepted April 20, 2026 at 15:15 GMT-7

iMac Intel 27" EMC 2639: Slow Write Speed (2TB Crucial Bx500 SSD) No Matter What

Sun, 19 Apr 2026 12:09:17 -0700

Hello,

I have a late 2013 27" that I replaced the failing HDD with a new 2TB Crucial Bx500 SSD.

Write speeds are an abysmal 20-40MB/s no mattter what.

I have also replaced the SATA cable AND enabled Trim.

I have tried also formatting the drive to exFat and then back to APFS with a clean install of Catalina, and then migrated the data again with migration assistant.

Originally, I thought the drive or cable was bad, so I replaced both again.

The issue persists. Write speeds hover from 20-40 MB/s.

Thank you for your consideration and help. I will be sure to respond as promptly as possible.

⟐ Commented April 19, 2026 at 12:09 GMT-7

iMac Intel 21.5" EMC 2428: iMac 2011 only #4 diagnostic LED is lit problem after upgrade

Thu, 16 Apr 2026 07:05:48 -0700

Hi everyone, I am kind of new here so here is my little story which I am having at the moment.
I have been diagnosing my iMac 21 mid 2011 for about a month, and I cannot get it to start back up no matter anything that I've tried and diagnosed, I only get #4 diagnostic LED to lit which is for LCD panel/inverter, nothing else.

First I thought it was the PSU on it's way to failure from age, but purchasing a new replacement didn't made any difference.

Then I've thought the internal connector which goes from power supply to the mb (motherboard) which gives it power and it may have been damaged while I disconnected it from the PSU, and I may have to get it, nothing changed.
But, one interesting thing is that both PSU's giving high pitched noise and "clicks" one or 2 per 3 seconds or so. I can record it as a voice memo if needed.
After that I thought the iMac's chassis may shorting components inside, so I measured voltages with the beeper on multi, everything is fine on that side. (no beeps)

As motherboards rarely fail, I also purchased a replacement, which also did no difference.

I think I have verified everything that could come to my mind, and I simply cannot get it power on no matter what I have tried. I am mostly specialist in laptops, so this is my first attempt and experience on getting inside an iMac.
I really hate throwing electronics away, I always try to diagnose them in every possible way. I have no one to ask and who could assist me in helping with this, as everyone who I know are always with their stuff.

If any more info is needed or I may have something missed during diagnostics, please please let me know, I will very much appreciate it.

⟐ Commented April 16, 2026 at 7:05 GMT-7

iMac Intel 27" EMC 2429: How to get rid of iCloud lock?

Fri, 10 Apr 2026 20:06:02 -0700

I have a 2011 iMac but It was iCloud locked and when I go to do a clean install it has an EFI lock. How Can I get rid of this?

⟐ Commented April 10, 2026 at 20:06 GMT-7

iMac Intel 21.5": Replacing my ssd drive

Sun, 05 Apr 2026 10:21:47 -0700

My drive is dead. How easy is it to replace (or is it worth replacing)? If I do replace it, can I restore my system from a backup of the drive or do I need to install a new operating system on the new drive? It is a 21.5 “ 2.7GHz Intel i5.

iMac: I have no sound in chrome on my iMac

Sat, 04 Apr 2026 05:38:11 -0700

I currently have no sound in Chrome on my IMAc at startup

⟐ Commented April 04, 2026 at 5:38 GMT-7

iMac Intel 24" EMC 2267: iMac dead. used as a monitor lcd panel

Thu, 02 Apr 2026 23:00:39 -0700

Hello , First sorry for my English . I use google translator to help me :(

I have everything you need (or so I think) to use my imac lcd panel (panel LM240WU2 ( SL) ( B4 ) ) as a monitor for other pc

http://i62.tinypic.com/112e876.jpg

http://i61.tinypic.com/2mwxct2.jpg

also I connect the cable from the inverter to the lcd

this http://i59.tinypic.com/f10dts.jpg to http://i57.tinypic.com/f2itxd.jpg

Connect the power cord from the iMac ( white ) energy to the panel. and I connect the power adapter to the board vga 12V 2A

but does not work , connect via a PC to give vga video signal and does not work

do I wrong ?

Help please :(

⟐ Answered April 02, 2026 at 23:00 GMT-7

iMac 27" 2017: Will an HDD from an existing fusion drive work with a different ssd?

Tue, 31 Mar 2026 12:30:29 -0700

I have an iMac 2017 that is dead, will not power on, and I would assume it's the logic board since power supply replacement didn't help. I have another one of the same iMac that is working, and I want to move the HDD from the bad imac into the the good one. I want to avoid removing the logic board on the new one if possible, so the question is: can I just move the HDD from the bad iMac to the good one without moving over the SSD from the fusion drive? All help is appreciated, thanks!

⟐ Answer accepted März 31, 2026 at 12:30 GMT-7

iMac Intel 27" EMC 2546: Help identify the pinout of the PSU (A1419, EMC 2546)?

Thu, 26 Mar 2026 17:18:53 -0700

Hi all, I am trying to do a monitor conversion and hoping to reuse the PSU. The model number is ADP-300AF T. It has 3 connectors, other than the AC input.

One big 12 pin molex connector connected to the logic board.
One small 2 pin connector connected to the power button.
One small 7 pin connector, connected to the logic board via a flat cable.

The big 12 pin molex connector is apparently the 12V rail. It's also confirmed by the schematic.

The 2 pin connector for power button is probably a passthrough to the logic button. The PSU usually needs a PS_ON pin to be pulled to the ground to keep on, if it's like an ATX PSU.

The 7 pin connector probably has that PS_ON pin, along with some other pins. I'm trying to figure out their functions. According to the schematic, they are:

PWR_BTN_R
GND
SMC_ACDC_ID_R
TSNS_ACDC_N
TSNS_ACDC_P
GND
BURSTMODE_EN_R_L

So, it confirms my suspicion about the power button. Pin 1 must be the power button pass-through. I looked up burst mode, which I probably don't need to worry about. But I'm unclear about the rest 3:

SMC_ACDC_ID_R
TSNS_ACDC (Positive and Negative)

Can someone shed some light on them?

P.S. does anyone know what kind of connector it is? I hate cutting the original cable. Worst case, I can solder wires to the PCB but it's kinda hard to do with the connector in place.

Schematic:

Connector:

⟐ Commented März 26, 2026 at 17:18 GMT-7

iMac Intel 27" Retina 5K Display 2019: Maximum fan speeds and CPU throttled after replacing CPU thermal paste

Wed, 25 Mar 2026 15:53:47 -0700

I decided I needed to replace the thermal paste on my iMac because the temperatures were rising, along with the fan speed.

My iMac is a 2019 5K iMac 27in with an Intel i9 processor at 3.6GHz. (iMac19,1 - EMC 3194)

After putting Arctic Silver MX-6 on the heat sink and reassembling the Mac, when I start it up it is very slow to boot and is very sluggish. The fan is running at full speed.

I have reset the SMC and the PRAM several times, and have checked and re-checked all the cable connections to no avail.

It is running Sequoia 15.7.4.

Has anyone got any suggestions for a fix?

⟐ Answered März 25, 2026 at 15:53 GMT-7

iMac Intel 21.5" Retina 4K Display 2019: Harddrive upgrade > no harddrive nor cables in my iMac?

Wed, 25 Mar 2026 06:10:48 -0700

So, I my harddrive didnt work anymore, was only able to run my imac DGKYKHQ4JWF2 → iMac (21.5" Retina 4K, 2019)
👉 Modell: iMac19,2

by adding on an external drive. So i ordered the kit with and SSD, opened it and to my surprise the slot for the harddrive was empty and I also cannot see any cable where i would attatch the SSD I got to. Does anyone have an idea whats going on and how i can manage to install my SSD as i was planning to according to this guide here: https://de.ifixit.com/Anleitung/iMac+Int...

Thank you!

⟐ Commented März 25, 2026 at 6:10 GMT-7

iMac Intel 27" EMC 2309 and 2374: iMac won't turn on. Only LED four is on in standby

Tue, 24 Mar 2026 12:44:16 -0700

iMac won't turn on. I assumed it would be the power supply but found this when I opened it up (glass and LCD apart and iMac plugged into the wall. LEDs 1, 2 and 3 are off BUT number four is ON. I've replaced power supply just to see but the same situation...any ideas? Thank you

⟐ Commented März 24, 2026 at 12:44 GMT-7