Screeching iMac at startup!!

MDLarson

MDLarson

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Well, I turned on an original bondi blue iMac today and was surprised to hear a loud screeching sound! It occured a few seconds after the startup chime and lasted 2 seconds. It could be described as a smoothly descending scale, sort of like somebody running their finger down a guitar string. It would be on the higher pitch range.

It is working like normal at the moment. I tried restarting and also shut it down and started up again. Is that strange or what?
 
Yep, strange! Did it sound like a mechanical screech, or did it come from the speakers (more like a digital or electronic screech)?

If it sounded more mechanical, I would suspect either the hard drive or the CRT.
 
My iMac DV used to make the same noise but when it was powering off. If it is the same noise it is electronic, not mechanical, quite loud and gets lower in tone and last for a couple of seconds. I have heard it is the sign of an analogue board dying in the iMac but mine disappeared after I updated the firmware to fix a (maybe related) display problem. That was about a year ago and was the last firmware update apple issued for the CRT iMac. Sorry - have no idea of the version number. Since then the scream has not come back. Maybe you could make sure the firmware is up to date.
 
I'm gonna call it a hardware produced sound although I really don't know. It was a very smooth thing. Another sound illustration might be like a slide whistle.

If it happens again, I'll post it! Hopefully it won't though. I don't really want a slide whistle iMac! :)
 
dflett said:
Maybe you could make sure the firmware is up to date.
Click to expand...
As I understand it, you need to update the firmware before installing Mac OS X (it's running Mac OS 10.3.5). I try to apply firmware updates regularly anyway, so I'm 80% sure it's got up-to-date firmware on it.
 
Yes, the CRT iMac firmware must be updated from MacOS 9: the only reason I keep it installed on the machine, otherwise its 10.3.5 too.
 
Ah. We're talking about 2 issues here:
1) Yes, firmware updates need to be installed from Mac OS 9.
2) In order to install Mac OS X, firmware updates need to first be installed (I forget which FW version exactly).

I don't have OS 9 installed on the computer at the moment... otherwise I'd check. Is there a way to check the firmware in Mac OS X?
 
MDLarson said:
Is there a way to check the firmware in Mac OS X?
Click to expand...

Sure, the Hardware Overview in your System Profiler will show your firmware version (the item called "Boot ROM version" is actually your system's firmware)
I think on an original Bondi iMac, the latest version should be approximately 3.0f2 (I'm not sure about the f2 part) A slot loading iMac should show version 4.1.9
 
I had an older Mac (OS 8) do that. It was the speakers. When I put the speakers on mute, it went away. Then I moved the sound volume to the middle. After that it never made the noise.
 
DeltaMac said:
Sure, the Hardware Overview in your System Profiler will show your firmware version (the item called "Boot ROM version" is actually your system's firmware)
Click to expand...
Ack! Boot ROM Version does not appear in my Hardware Overview:
Machine Model: iMac
CPU Type: PowerPC 750 (2.2)
Number Of CPUs: 1
CPU Speed: 233 MHz
L2 Cache (per CPU): 512 KB
Memory: 512 MB
Bus Speed: 67 MHz
Click to expand...
I checked the Hardware Overview via Mac OS X on my B&W G3, and indeed the Boot ROM Version is listed below the Bus Speed. It's not listed on the iMac! Wierd.
 
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