external display monitor

I have an external display monitor attached to my MacBookPro. Recently, I have had to start it several times in order for it to come on. Now, after over 2 dozen start-ups, it is not turning on. I have cleared most of my desktop subject matter. It is still not responding. How do I get my display monitor to start when I start my MacBookPro?

First- make sure your MacBook Pro is running off AC power and not its battery. An external monitor is automatically disabled when your machine is on battery. If you are running off AC power, try keeping the lid closed on your MacBook Pro when it starts and use the procedure called "clamshell mode".

chscag said:

First- make sure your MacBook Pro is running off AC power and not its battery. An external monitor is automatically disabled when your machine is on battery.

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I hate to correct you, but this just isn't true (unless you were referring to some kind of monitor that draws power from the computer?).

I have a second monitor on my MacBook Pro, and can unplug the power easily and the machine just keeps right on going, with the second monitor behaving exactly as normal.

chas_m said:

I hate to correct you, but this just isn't true (unless you were referring to some kind of monitor that draws power from the computer?).

I have a second monitor on my MacBook Pro, and can unplug the power easily and the machine just keeps right on going, with the second monitor behaving exactly as normal.

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Not all of them do - Neither my MBP nor my MBA will detect a TV if they're running from battery. Have not tried having the power plugged in while connecting to the TV and then unplugging the power to see if it will continue to function as you're noting.

In the ops case, if this is an issue of the connection to the TV use to work and now it's not, I'd try:

a) disconnect and reconnect the cable from both the MBP and the TV.
b) SMC reset, while you're at it, may as well do a PRAM reset
c) adapter and/or cable - try a different one - if using an adapter, try it first, there are many more reports of adapter failures than cable failures

I hate to correct you, but this just isn't true (unless you were referring to some kind of monitor that draws power from the computer?).

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You are correct, I stated it poorly. Tom said what I should have in that the monitor is not detected if the Mac is operating on battery.

Ah I see what you were getting at, but TV ≠ monitor. Thanks for clearing that up.