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Manu182

macrumors newbie
Original poster
Feb 1, 2022
13
3
Hello all,

I have here a MacBookPro9,2 (Macbook Pro 13 Mid 2012) with the latest Monterey in version 12.6. Currently I have the problem that I get no signal on my external monitor via MiniDP. I have tested two different adapters. The integrated display goes black briefly and comes back again.

I have not used the Macbook on an external monitor for a very long time now. I upgraded it with 512GB SSD, 16GB RAM and WiFi BCM943602CS. Everything works great except the external display doesn't like it.

Processor is a 2.5 GHz dual-core Intel Core i5 and accordingly with the integrated GPU Intel HD Graphics 4000 1536 MB.

Additionally, a Windows 10 legacy is installed. Again, the external monitor does not work. I have done a PRAM and SMC reset.

Anyone else have any ideas? Is it because of OpenCore EFI? However, it only boots my macOS and not Windows.
 

Manu182

macrumors newbie
Original poster
Feb 1, 2022
13
3
Have you confirmed that both adapters and the monitor works with another mid 2012?
Yep, both working. Tried on an iMac 2011 with no issues.
Tried booting from an external drive with an OS supported by your Mac?
Good point!
I just tested a Catalina (last OS which is officially supported) again. Here I have the same problems. Display goes black briefly, but no signal on the external monitor. Now I'm a bit confused where the problem could be.
 
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Manu182

macrumors newbie
Original poster
Feb 1, 2022
13
3
The diagnosis only says that it cannot find wifi. It must be the wifi upgrade. Otherwise everything is OK.
 

Audit13

macrumors 604
Apr 19, 2017
6,563
1,725
Toronto, Ontario, Canada
Does the MacBook seem to boot to the desktop even though the display is blank?

Have you tried shining a bright light on the MacBook screen to see if there is anything visible? You could also try shining a light through the Apple logo at the top of the lid.
 

Manu182

macrumors newbie
Original poster
Feb 1, 2022
13
3
The MacBook display is totally fine. Everything is working perfectly, only this one issue with MiniDP. I have uploaded a Video where you can see that I connect the cable.

 

Manu182

macrumors newbie
Original poster
Feb 1, 2022
13
3
The port recognises something, otherwise the picture on the macbook would not briefly go black. But yes, in the meantime I also assume that it is defective. :(

Thank you very much for your support!
 
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Jesse_Bassett

macrumors newbie
Jan 29, 2021
16
7
Inver Grove Heights, MN
I know how to fix this! So if you open the bottom of the macbook up, there is a little switch on the bottom left side. It curves around and if it is bumped in anyway, the mac will not turn on. Make sure you reset this switch by unplugging it, then plugging it in. It will work! I have done this myself just recently.
 

Manu182

macrumors newbie
Original poster
Feb 1, 2022
13
3
I know how to fix this! So if you open the bottom of the macbook up, there is a little switch on the bottom left side. It curves around and if it is bumped in anyway, the mac will not turn on. Make sure you reset this switch by unplugging it, then plugging it in. It will work! I have done this myself just recently.
What for a switch do you mean? Do you have picture for example?
 

aijil

macrumors newbie
May 29, 2009
3
0
Couple of things to consider:
Try a different cable, or test your cable with another computer.
Try installing Windows via bootcamp and see if the port works in Windows

The port recognises something, otherwise the picture on the macbook would not briefly go black. But yes, in the meantime I also assume that it is defective. :(
Thank you very much for your support!
 

Manu182

macrumors newbie
Original poster
Feb 1, 2022
13
3
I buyer a used MacBook Pro 13 mid 2012 with i7 and only switched my harddisk to the new one. External Display now works as it should. So yes, it’s a hardware issue.
 
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