Black screen (of death?)

Sad Professor

Okay I had a pretty scary experience with my 7 month old c2d iMac last night. I was testing my firewire backup drive to see that it was bootable, which it was, and I was in the middle of something when suddenly—

Poof!, without any warning my imac just restarted by itself. It then made the usual start-up chime, disk noise, white light, etc. Except—much to my horror—I couldn't see anything, the display was black and wasn't coming on :eek:. So I forced another restart and—now I was getting really scared—the screen was still black. Cue me, panic stricken, restarting several more times with the exact same result: no screen.

I then tried zapping the PRAM which didn't seem to even work (can anyone confirm this works the same way on intel imacs?). After this failed I tried resetting the SMU (disconnecting everything and unplugging the imac for 30 seconds) and—

—finally, the display came on! I reconnected everything and booted up from my internal start-up disk and then...

..it HAPPENED AGAIN, the screen just went black. I restarted several more times, resetting the SMU, etc with mixed results each time, sometimes it hung during start-up while the display remained fine. Until eventually it started making weird rolling-type noises (not the hd) on startup (still no screen) and I could hear very faint beeping.

I now began to think that the RAM was the culprit as I had this exact same problem (black screen) after installing a new RAM chip about 4 months ago. So I turned everything off and removed both RAM chips, re-seating them both and making sure they were secure and...(after one minor hiccup/repeat when one of the chips wasn't recognised)...

It worked!

Since then everything has been fine. I've run Techtools and memtest several times, and everything checks out. So I'm putting this down to the RAM slipping loose....but... I still have doubts.

Has anyone else ever had this happen? Is it possible for RAM to slip loose like this?

Anyway I just thought I'd share this with people in case they ever have the same problem.

triple h

Sad Professor wrote:

—now I was getting really scared—the screen was still black. Cue me, panic stricken,

You been scared scares me.

Anyway, thank god I never had that problem.

" I then tried zapping the PRAM which didn't seem to even work (can anyone confirm this works the same way on intel imacs?). After this failed I tried resetting the SMU (disconnecting everything and unplugging the imac for 30 seconds) and—"

Zapping the pram ??????? if i heard someone talking about zapping a pram the first image that would come into my mind is Sar Trek or DR Who and some evil guy with a weapon. Shows what i know.


Anyway i was just wondering why would someone with a new computer need to install new RAM ?

Also i notice the imac can move quite a bit on the desk ( my imac is upstairs in the house, so it is not cement ground) if someone bags the door or jumps on the ground. could this be a reason for something to get loose.

failsafe

Never happened with my imac, but it sounds pretty similar to what happened with my dad's G5. The first time it happened i think he just left it plugged out for a day then did a few reboots etc, the second time the screen was black for a few days, but everything else seemed to be running (fan went a bit crazy), he went abroad for a few days came back and it just worked!

I realise that wasn't helpful at all, but I'd be interested in seeing if anyone knows the prob with your imac, as it may be the same/similar problem as my dad's g5.

Sad Professor

triple h wrote:

Zapping the pram ??????? if i heard someone talking about zapping a pram the first image that would come into my mind is Sar Trek or DR Who and some evil guy with a weapon. Shows what i know.

The PRAM/NVRAM is like an internal battery that remembers the time/start-up disk, etc. "Zapping" it can often solve start-up problems. Although it was unlikely to have been the cause of my problem.

Anyway i was just wondering why would someone with a new computer need to install new RAM ?

'cause I just got the standard configuration with 1GB of RAM, which just isn't enough. I thought it would work out cheaper buying it separately but tbh I probably should have had it BTO like you did. You got yours configured with 2GB didn't you, triple_h?

Although with RAM prices always dropping I'll probably upgrade to 3GB shortly.

Also i notice the imac can move quite a bit on the desk ( my imac is upstairs in the house, so it is not cement ground) if someone bags the door or jumps on the ground. could this be a reason for something to get loose.

Yeah i was thinking this as well. I often kick off my desk and frequently insert/remove the headphone jack, which could cause quite a bit of vibration I guess.

Sad Professor

failsafe wrote:

Never happened with my imac, but it sounds pretty similar to what happened with my dad's G5. The first time it happened i think he just left it plugged out for a day then did a few reboots etc, the second time the screen was black for a few days, but everything else seemed to be running (fan went a bit crazy), he went abroad for a few days came back and it just worked!

I realise that wasn't helpful at all, but I'd be interested in seeing if anyone knows the prob with your imac, as it may be the same/similar problem as my dad's g5.

Does your dad still have the same G5? Has the problem ever re-occurred?

What you're describing (especially with the fan) is almost certainly a SMU (System Management Unit, it controls the power functions) problem. Certain generations of the G5 iMac were riddled with these issues. The typical symptoms were spontaneous restarts, failure to successfully wake from sleep and crazy fan behaviour. I don't recall if the problem was ever solved via a firmware update or if it was a hardware fault.

It's quite possible my problem was with the SMU (or SMC as it's now called) as well, although I've only ever heard my fans spin up to full once, and it was only for a moment. However, the SMC could certainly cause the display not come on, and I've heard it can become corrupt due to electrical surges and there was lightning on Friday so maybe...

But I didn't experience any problems with my ibook or Dell or any other electrical item in the house. It just seems like too big a coincidence that I was installing RAM when this issue first appeared. And the black screen was accompanied by some pretty nasty crashes (which weren't kernel panics) so it makes the most sense that it's RAM related.

triple h

Sad Professor wrote:

'cause I just got the standard configuration with 1GB of RAM, which just isn't enough. I thought it would work out cheaper buying it separately but tbh I probably should have had it BTO like you did. You got yours configured with 2GB didn't you, triple_h?
.

Yes i got 2GB and i remember you and a few others saying it would be cheaper to buy RAM elsewhere. I knew nothing about RAMS, (never mind putting my RAMS into my computer) I reckoned it would be safer to buy 2GB .

Sad Professor

triple h wrote:

Yes i got 2GB and i remember you and a few others saying it would be cheaper to buy RAM elsewhere. I knew nothing about RAMS, (never mind putting my RAMS into my computer) I reckoned it would be safer to buy 2GB .

Well it does work out cheaper to buy elsewhere but then you have to consider that you're removing RAM to make room for it. Which depending on RAM prices isn't always worth the hassle.

At the moment Apple are charging 180 euro to upgrade the iMac to 2GB. It costs 85 euro from Crucial.

Quite a saving I think.

spidermonkey

plastikman

sounds like a heat problem the imac g4 has a terrible cooling system thats why the discontinued them. try hooking a hover to the top air vent next time it turns off.. then turn on the Hoover and it should suck out all the dust and cool down the inside... or do what this guy did

http://www.icon.fi/~jtki/imac.html

saoranach

Hi Ive had pretty much the same thing happen to my macbook. It was in standby and then when I went to start it the screen was all grey.

I turned it on again and can hear the fan and the powerlight is on but nothing happens after leaving it like this for a while I get a question mark on the screen and thats it.

Ive tried powering it off, taking the battery out etc... all had no effect

Any advise welcome
Thanks

Sad Professor

saoranach wrote:

Hi Ive had pretty much the same thing happen to my macbook. It was in standby and then when I went to start it the screen was all grey.

I turned it on again and can hear the fan and the powerlight is on but nothing happens after leaving it like this for a while I get a question mark on the screen and thats it.

Ive tried powering it off, taking the battery out etc... all had no effect

Any advise welcome
Thanks

Somewhat different problem. If you're lucky it's just a issue with the system software (and you can repair/reinstall); if you're unlucky the hd is f**ked. Insert the OSX cd, it should boot up from it, open Disk Utility from the Utilities menu and see if the hd is still visible. If so try repairing it.