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A2116 / 2019 / 3.6 GHz quad-core i3, 3.0 GHz 6-core i5, or 3.2 GHz 6-core i7 processor. Released March 19, 2019.

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iMac boots up but no display after replacing HDD with SSD

My iMac 4K Retina Display will NOT power on at all: No backlight, no LCD (as far as I can tell, with a flashlight shined on it). It will boot up to an external display.

The internal display doesn’t even appear in System Report when looking at the list of displays.

I was extremely careful removing the LVDS cable. Thinking that I may have damaged it, I ordered a brand new one, which hasn’t helped at all. Of course I’ve also tried an SMC reset, NVRAM reset.

ALL I did in the original repair was:

  1. Remove original HDD
  2. Install new SSD
  3. I was careful to make sure the iMac wasn't plugged to power when disconnecting and reconnecting the internal display

The fan also runs at full speed when the machine is powered on, which I suspect is just because it can’t see the internal display.

Apple’s diagnostics shows two issues:

There may be an issue with the System Management Controller (SMC).

Reference Code: PFM006


There may be an issue with the display.

Reference Code: VFD001

I've also peeked inside when powering on the unit with the internal display connected, and LED1+LED2+LED3 light up. LED4 lights up but is faint. LED5 does NOT light up at all.

Any idea on what I could try out next?

Update (04/13/23)

@danj I've attached the pictures of the logic board + new eDP cable

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Answer this question I have this problem too

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2 Answers

To be clear, the fourth & fifth LEDs won’t light until you have the display plugged in. Without a cable extension set it’s just hard to see it without stressing the logic board display connector.

FYI - The displays ribbon cable in the newer retina systems is either eDP or iDP or custom as in the case of the 5k systems as Apple was ahead of the industry! We just call it the Display Cable in all of these cases. LVDS became popular as that was the signaling used in the older Unibody systems.

Did you follow the steps in our guides and use the special pizza cutter?

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Absolutely I was extremely careful! I used the pizza cutter to remove the adhesive. And yes, I ordered the eDP 4K replacement cable.

Any other advice? And thanks for your help!


@macfan66 - Let’s get some pictures of the logic boards display connectors and the cable end. I think the connector was yanked.


@macfan66 - Is it possible you flipped the cable over? Look at the circuitry around the display connector do you see any discolored or burnt components.


@danj I double checked that as a possible problem. The cable has a "key" in the form of a notch/dot on one side of the cable, which match the holes on either side of the logic board connector. Like I said, I'm at a loss as to what could be wrong.

Tomorrow, a friend of mine is bringing his iMac 4k 2019. He's upgrading the NVMe and SSD drives on his, and will test his display on mine.


@macfan66 - I’ve seen people forcing things, not saying that here just making sure.

Yes, trying a different display is what I would do.


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@macfan66 did you manage to solve the rpoblem on your friends imac?

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macfannd will be eternally grateful.
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