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I have a ~2009 MacBook Pro (model MacBookPro5,3) with OS X 10.6.8.

I'm trying to use a Apple Mini DisplayPort to VGA adapter to connect to an external monitor. I've tried two different monitors and two different VGA cables so far, and no luck. Both work fine with my ThinkPad; simply plug and (dis)play.

I believe I've already tried every permutation of the order of connecting things, as well as with power on or off. But the MBP just doesn't seem to recognize the monitors.

For example with monitor powered on, when I insert the DisplayPort adapter, the MBP screen turns blue for a second or two ... but then I don't see anything on the monitor or anything change in System Preferences > Display.

I've never tried to connect an external monitor to a MBP before -- I didn't expect it to be this difficult. Is there something dumb/obvious I'm overlooking??

EDIT: Showing System Profiler result for Graphics/Displays when the external monitor is connected but not recognized via the mDP. Note that it shows two adapters:


NVIDIA GeForce 9400M:

  Chipset Model:    NVIDIA GeForce 9400M
  Type: GPU
  Bus:  PCI
  VRAM (Total): 256 MB
  Vendor:   NVIDIA (0x10de)
  Device ID:    0x0863
  Revision ID:  0x00b1
  ROM Revision: 3448
  gMux Version: 1.8.8
Color LCD:
  Resolution:   1440 x 900
  Pixel Depth:  32-Bit Color (ARGB8888)
  Main Display: Yes
  Mirror:   Off
  Online:   Yes
  Built-In: Yes
Display Connector:
  Status:   No Display Connected


NVIDIA GeForce 9600M GT:

  Chipset Model:    NVIDIA GeForce 9600M GT
  Type: GPU
  Bus:  PCIe
  PCIe Lane Width:  x16
  VRAM (Total): 256 MB
  Vendor:   NVIDIA (0x10de)
  Device ID:    0x0647
  Revision ID:  0x00a1
  ROM Revision: 3448
  gMux Version: 1.8.8
Display Connector:
  Status:   No Display Connected
Display Connector:
  Status:   No Display Connected
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up vote 2 down vote accepted

Have you tried a SMC reset? Often fixes crazy port issues.

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Thank you. I reset the SMC but it did not help. I did notice the blue screen would sometimes now last ~3 seconds instead of 1. But no other change. By the way, to reset the SMC I followed the instructions pressing SHIFT+CONTROL+OPTION and power at same time, and releasing all at same time, then pressing power again. But I didn't see any obvious evidence that I actually reset the SMC -- is there supposed to be some indication? – Greg Hendershott Mar 28 '12 at 16:08
Sadly, no. What does System Profiler show in the Graphics/Displays section when you have the external monitor connected? Also, have you run Software Update with the mDP adapter connected, to see if you need to install the firmware update? – da4 Mar 28 '12 at 16:34
1. I'll update my question to show the System Profiler results as they're too long to fit into a comment. 2. Ah, good idea. I ran Software Update with the mDP attached. But it did not recommend an update. – Greg Hendershott Mar 29 '12 at 13:11
Also, I borrowed a mDP->HMDI and tried that with a big screen TV that has HDMI input. It worked! So the mDP itself seems OK. Unfortunately I need to connect to VGA for a monitor I want to use, and also for the case of connecting to a projector or whatever might come my way. – Greg Hendershott Mar 29 '12 at 13:48
OK I borrowed another mDP->VGA adapter and it worked instantly. The original mDP->VGA adapter must be faulty. @da4 thank you for all your help and great suggestions; I'm going to mark your answer as accepted. – Greg Hendershott Mar 29 '12 at 15:13

Under OS X, open and enter the following command:

defaults write NSGlobalDomain AppleFontSmoothing -int 2

Then, reboot your Mac.

This will enable subpixel font rendering on non-Apple LCDs. However, this tweak is known to have all kinds of positive side effects, fixing various random display issues.

I hope it fixes your issue, too! And if not, oh well, it was worth a shot.

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