External monitor not recognized!

Question

External monitor not recognized!

I have a Philips 180P2 external monitor hooked up to my iMac 2.8 GHz, 24", which was running fine until my upgradte to SL this afternoon. Now (among other little "quirks") the external monitor can't recognize the signal from the iMac ... or rather, the iMac won't display there...

What's odd is that I had, for example, Safari on the external monitor and, when I start that browser, it won't show as it running on the external Philips monitor ... which isn't running (yes, power is on and cable is plugged in). When I unplug the monitor adapter from the back of the iMac it switches to one-display mode again and Safari is shown on the iMac.

The system preferences show the monitor and its position fine ... what's going on?!

Any and all help is REALLY appreciated. Thanks!

iBook G4 14" & iMac G5, iMac 24" 2.8 GHz, AppleTV 2.0, Mac OS X (10.5.2)

Posted on Aug 29, 2009 5:50 AM

Reply

Answer 1

Aug 29, 2009 7:33 AM in response to Roger Kaufmann

My Mac Mini (latest gen) is hooked up to my Sony KDL 32M4000 (32" LCD TV) and likewise, after installing Snow Leopard the monitor is not recognized. What's funny is that while booting I get the gray screen with the spinning thing in the middle, but then it just goes away.

Kinda hard to trouble shoot when you can't see what is going on.

I used to (with 10.5) screen share from my laptop, but that seems to be broken too, all of a sudden. So I've got a dead Mini now.

Reply

Answer 2

iPud

Level 1

25 points

Aug 29, 2009 7:52 PM in response to puhi macster

same issue, macbook 2.17GHz and a Sharp 37" LCD. No video out.

Reply

Answer 3

Argy77

Level 1

9 points

Aug 30, 2009 12:11 AM in response to iPud

Same for me too, MacPro (early 2008) with ati Radeon HD4870 attached to 24" Cinema via mini display port and a 42" Samsung Plasma Screen attached to the dvi connector. The DVI does not work any more. I get no signal.

Reply

Answer 4

Aug 30, 2009 9:43 AM in response to Roger Kaufmann

Ever since installing Snow Leopard I lost my native screen resolution of 1920 X 1024 on my HP monitor. The highest resolution I get to choose is 1600 X 900. I'm running a stock Mac Pro with an HP w2338h. Very disappointing. Now everything is interpolated, and looks awful!

Reply

Answer 5

Ninike

Level 1

0 points

Aug 30, 2009 1:31 PM in response to Roger Kaufmann

I had the same problems with my MBP 15 and a Acer AL2051W monitor. I removed the DVI connection and used the VGA-connection instead and this works for me.

Reply

Answer 6

Aug 30, 2009 3:41 PM in response to Roger Kaufmann

I've had similar problems (see http://discussions.apple.com/thread.jspa?threadID=2132912&tstart=0) with my second monitor. When I downgrade the display of the external to 1600x1000, then the internal monitor of the imac to 1600x 1200, the display on the external is not very good. However, if I then revert the external to 1680x1050 and the internal to 1900x1200 I can get both back to what things were before updating to snow leopard. However, when I then switch off the imac for a while and then switch back on again the external switches back and forward between no display and a fleeting glimpse of the desktop.

Reply

Answer 7

Ed Jose

Level 1

10 points

Aug 31, 2009 9:46 AM in response to Roger Kaufmann

Same problem with a 24" HP w2558hc LCD. Worked fine prior to Snow Leopard.

Reply

Answer 8

Aug 31, 2009 10:36 AM in response to Roger Kaufmann

Argh. Same issue here. I have three Westinghouse LVM47-W1 monitors hooked up to two "ATI Radeon HD 2600" cards in a MacPro3,1. I can't get the machine to recognize any of the displays. I tried resetting the PRAM but it didn't work.

Reply

Answer 9

Aug 31, 2009 4:35 PM in response to Greg Welch

BTW, my external displays are all 1080p, and all connected via DVI. (And all three worked fine w/ Leopard/10.5.)

I reset the PRAM/NVRAM, power cycled the machine, etc. No luck (under Snow Leopard).

I created a new separate boot partition and did a clean install of Snow Leopard/10.6 on it, and when booting from that partition the machine/OS still cannot see the displays.

I hooked up a smaller spare Dell 1600x1200 flat panel display via DVI and it works fine (under Snow Leopard).

So perhaps Snow Leopard/10.6 has an issue w/ some external displays. I'm bumming. (I only decided to upgrade this machine after smooth Macbook Pro and iMac updates.)

Reply

Answer 10

branman

Level 1

59 points

Aug 31, 2009 10:00 PM in response to Roger Kaufmann

Yep, me too. First try it worked after a long time attempting to sync. Then I woke up my MacBook Pro from sleep and it showed up in black and white. Since then have disconnected/reconnected, restarted, shut down, etc., and cannot get it to sync with my external display at all. Have tried 'detect displays' multiple times as well...

Please fix, Apple!

Reply

Answer 11

Pietie

Level 1

0 points

Sep 1, 2009 1:25 AM in response to Roger Kaufmann

My (admittedly oldish) 1024x768 Compaq LCD monitor (connected using VGA adapter) to a 24" 2.8 GHz iMac won't come out of power saving mode. The correct resolution is detected, and unplugging the monitor switches the machine to single-monitor mode. When plugged in I can move windows to the monitor - just not see anything. So just adding my voice in the hope that we might be heard!
Cheers.

Reply

Answer 12

Sep 1, 2009 1:29 AM in response to Pietie

Yep, Pietie's description matches my situation exactly (VGA adapter and all) ... has anybody heard of Apple actually recognizing this issue?

Reply

Answer 13

bil

Level 1

4 points

Sep 1, 2009 9:46 AM in response to Greg Welch

FWIW, we worked around Greg's problem using a Gefen DVI Detective programmed to simulate a 1080p display. This is a device that can memorize an EDID on a working system, and when you put it on the computer, the computer sees the stored EDID. They cost about $80.00.

What we did was hook the DVI Detective between a PC and a similar westinghouse display to Greg's system, and loaded that display's EDID. Then we moved the DVI detective to his system, and the mac saw that EDID and enabled the display.

Reply

Answer 14

Baz G.

Level 1

0 points

Sep 1, 2009 12:34 PM in response to Roger Kaufmann

Same problem I can't get my 3rd party monitor (new samsung LCD) to work with 10.6 (it worked perfectly on 10.5) on my MacBook unibody. I'm using the Apple Mini DisplayPort->VGA.

I can get it work again by switching to the one-display mode and then back to dual display after each startup (or by selecting a non native awful resolution).

Apple please fix this bug!

Reply

Answer 15

Sep 1, 2009 5:43 PM in response to Roger Kaufmann

My MBP running DVI to Composite video to my tv is also having issues. It displays the correct picture (480i) but everything is Black and White. Absolutely no color is being displayed on my TV, and even moving the menu bar over to make it my primary screen doesnt fix the problem. Apple, hear our pleas!

Reply