iMac won’t boot with built-in display connected

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iMac Intel 21.5" EMC 2308

Model A1311 / Late 2009 / 3.06 or 3.33 GHz Core 2 Duo processor

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Barry @ifixanythink

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发帖于: 2018年2月7日

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iMac won’t boot with built-in display connected

It had a damaged 30-pin display connector (torn off by previous owner) on the logic board & also some minor damage to the 30 pin ribbon cable.

I bought a replacement connector and ribbon cable from eBay, just to be sure it would connect properly.

Numbers listed on eBay for the ribbon cable:

Part Number: 593-1006 922-9132

MPN: Y593-1006 922-9132

I reassembled the machine, but it would not boot at all. No startup sound, no beeps, nothing. However it does boot with the display disconnected.

I have ordered an adapter, Mini DisplayPort (Thunderbolt) to VGA/HDMI/DVI, to see if will run with an external display, as a workaround.

But I would much rather fix it properly, so it runs with the built in display. Can anyone shed some light on this?

@danj,

Only 1 LED's is on with all 4 monitor cables which I think is LED #1 as it is a little hard to see through the vent.
All 4 LED's are on with LVDS cable disconnected.
All 4 LED's are on with LVDS disconnected & backlight power cable connected.
All 4 LED's are on with LVDS disconnected, backlight power cable connected & the vertical sync ribbon cable connected. I am also getting a very dull grey illuminated screen/monitor & 3 minutes 10 seconds later screen/monitor goes dark i.e. from the dull grey.

Schematic mentioned below:

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Hold on here!! You need a mini-display port cable, NOT a Thunderbolt cable! While they look alike they are not the same!

由 Dan 完成的 2018年2月8日

What does the built-in diagnostic LED's telling you?

由 Dan 完成的 2018年2月8日

@ifixanythink "damaged 30-pin display connector (torn off by previous owner) on the logic board " post some pictures showing the damage on the board as well as the complete board. That way we can see what you see 在已经存在的问题里加入图片

由 oldturkey03 完成的 2018年2月8日

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Hold on here!! You need a mini-display port cable, NOT a Thunderbolt cable! While they look alike they are not the same! — Dan
@ifixanythink "damaged 30-pin display connector (torn off by previous owner) on the logic board " post some pictures showing the damage on the board as well as the complete board. That way we can see what you see 在已经存在的问题里加入图片 — oldturkey03

Dan @danj 声誉积分: 478.9千 Self employed contract worker 35 329 970 · Answer 1 · 2018-02-09T06:28:03-07:00

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Dan @danj

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@ifixanythink - Barry,

Thats pointing to a short somewhere. Did you get the external display adapter (mDP to VGA/HDMI/DVI) you ordered? I think you'll need to wait until you get it so you can see if the external display works. If it does with the internal disconnected we know the issue is localized within the internal display logic.

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@danj Thunderbolt v1 and v2 use MiniDP, v3 uses USB-C. See http://wikipedia.org/wiki/Thunderbolt_(i...

由 gradientzebra 完成的 2018年2月8日

@gradientzebra - Here's a bit more clarity on the differences: Thunderbolt and Mini DisplayPort : differences and compatibility

The issue here is using the correct cable. This is an older iMac 2010 which is uses DisplayPort to support external monitors. You can't use Thunderbolt cables on it (I know I've tried). The issue is which came first in this case the iMac is older than the thunderbolt standard so it sets what is needed here.

由 Dan 完成的 2018年2月8日

@danj no worries eBay listing said it was mini displayport

由 Barry 完成的 2018年2月8日

@danj A bit confusing. I was under the impression that Thunderbolt was the signal, and MiniDP was the physical cable. I still don't quite get it, but that's okay.

Also, I'm sure I posted the above message as a comment, did a mod move it or something? I didn't mean for it to be posted as an answer to this question.

由 gradientzebra 完成的 2018年2月8日

@gradientzebra - Even I'm confused at times ;-} !!

Basically, they are using the same connector. But, unlike mDP, TB has a front end driver circuit within the cable! This is what messes you up using it older systems. Think Passive - mDP Vs Active TB cable. The target device then sets which cable, As an example a mDP display only needs a mDP cable for either mDP or TB based system. And a TB device can only be connected to a TB system using of course a TB cable. I find that helps most of the time.

I moved it down so I could respond.

由 Dan 完成的 2018年2月8日

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Jimmy @jims2018 声誉积分: 1 · Answer 2 · 2018-04-20T17:34:21-07:00

Jimmy @jims2018

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发帖于: 2018年4月20日

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hi, i tried to remove the broken connector from my 2010 iMac 27" and while removing the excessive solder using the solder wick, i realized that pin 23 to 26 are connected and pin 27 to 30 are connected.

can you let me know if they are actually connected in the circuits?

based on your schematic above, 23 & 30 are NC, the rest 24 to 29 are LED returns 1 to 6. Does this mean they can be connected together?

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The schematic is for a laptop LVDS connection not a iMac.

由 Dan 完成的 2018年4月20日

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iMac Intel 21.5" EMC 2308

iMac won’t boot with built-in display connected

Update (02/07/2018)

Update (02/10/2018)

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