Second display on imac, keeps flickering off then on again

Bod

Bod

Bod

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I've posted this over at the Apple Support Forum too.

I have a 20" iMac (early 2008), which I've had for about 9 weeks or so.

After a week or two, I got rid of my PC and connected my Dell 22" monitor via DVI to the imac as a second monitor.

However, it randomly 'cuts out' for a second or so, then comes back on as normal. It's only about a second long, if that (about the length of time you usually get when you change resolutions or inputs on a monitor).

The main imac screen never does it, and the external monitor never did it on the PC (regardless of which of the inputs I was using...) infact, the external monitor has never done this before ever.

Any thoughts? Could it be a dodgy mini DVI converter? Dodgy iMac?

No amount of me twiddling, flicking, or wiggling any wires or hardware, can make it happen on command, its *always* as random as it gets.
It's done it loads of times tonight, but hasn't done it for a while up until tonight. Just does it when it feels like it
And the amount of 'off' time is ALWAYS the same...about a second or so.
 
Could be one of any number of things - I guess you need to start narrowing the cause down by elimination.

Do you know anybody with another mini-DVI adapter that you can borrow, or a Mac with mini-DVI that you can test your setup on, for example?
 
What graphics card have you got? Is it good enough to drive both monitors?

Try a different mini DVI adapter or a different Mac if possible.
 
Well I rang Apple UK support (Im still within my 90 days), and they had no idea. First tried blaming the monitor etc, then the cable.

I know it's either

A : The Mini DVI adapter
B : The Socket on the imac
C : The GFX hardware on the imac (The fact it drives the mac display fine I wouldnt have thought so)
D : Some sort of incompatibility perhaps? (I wouldn't have thought so).

I'm going to pop to the Trafford Centre later and get this mini-DVI adapter changed, see if that sorts it.

It was doing it quite frequently last night, but it hasn't done it at all today...grrr.
 
Okay, to rule out the socket you need to know if the monitor is fading off to blue and back a sign that the computer is detecting the monitor as disconnected, you didn't say this was the case, so my best bet is the adapter has gotten worn out, mine did and apple replaced it for me, it caused the exact issue you are describing and the imac doesn't know when you unplug a monitor from the adaptor only when you unplug the adaptor...

I guess it could be the graphics but like you said it works fine for the mac display...
 
unknowndomain said:
I guess it could be the graphics but like you said it works fine for the mac display...
Click to expand...

Well it will work fine for the Mac display, the GFX are designed to run that screen. It will only have problems with the second screen. Not sure that's the problem though, check the cable first.
 
Its definitely not fading to blue and black. It's like a very quick power cut, then back on again a second later.
 
Bod said:
Its definitely not fading to blue and black. It's like a very quick power cut, then back on again a second later.
Click to expand...

Does the frequency of the blackouts change when do different things on the second monitor or is it random?
 
From what I can gather it's completely random.

I normally have my Adium contact list, itunes, and colloquy on it, along with anything that VLC is playing. I thought I'd cracked it last night when I thought it never did it while VLC was playing on there.....then boom, right in the middle of top gear it did it ....lol

I've been to the Apple store who changed the adapter for me. Lets hope it doesn't do it again. It hasn't done it yet, but then it hasn't done it all day.

He said if it still continued to do it, to book me and my mac into the genius bar.
 
Nope, no loose cable here. No amount of wiggling and woggling can make it happen. It doesn't happen when connected to the PC either.

I changed the connector last night, and it was fine all night.
Woke the mac up this morning and within 10 minutes it had done it twice. Not done it since though.....

I'm going to be reformatting my mac soon, make sure it isn't an errant driver or software causing it (I have the proper monitor driver for the Dell, and also both displays are calibrated with the Eye One, so I want to rule everything out before I go in with the mac).
 
Do you have a Bootcamp install on it? If so, boot into Windows and see if it still does the same?

If it does, it could be hardware or the cable, if it doesn't it's likely to be a software issue.
 
I don't have bootcamp installed Olly, but I like that idea. Would rule out OSX.
 
I get this too at random times, and this is with my main monitor (I own a Mac Pro).

Very Weird.

I blame the Monitor, Apple never make mistakes!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


:p
 
Indeed they don't :p
Must be some Microsoft software that's left behind on a disc on the shelf somewhere...infecting me from a distance :D
 
Well, reformatted the mac last night and I was quite pleased, it didn't do it all evening (about 5 hours...although it has gone this long without flickering loads of times).

This morning it did it again :(

The most recent thing I did was run Eye-One monitor profiler about half an hour ago.
 
Bod said:
Well, reformatted the mac last night and I was quite pleased, it didn't do it all evening (about 5 hours...although it has gone this long without flickering loads of times).

This morning it did it again :(

The most recent thing I did was run Eye-One monitor profiler about half an hour ago.
Click to expand...

Try Apple again.

Have you tried a different cable or a different Mac?
 
was there ever an answer to this, I have exactly the same problem... its driving me out of my tiny mind !!

i have bootcamp/vista and the hp zr24w works fine there, although it was just as flakey before the latest windows update. It blacks out all the time in OSX.

it cant be the mini-dvi to dvi adapter or cable as they both work fine on windows....

im at a loss on this one....
 
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