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iteachmac, The Duke!
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Howdy, Im having some trouble getting my iMac to boot. _Its

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Howdy, I'm having some trouble getting my iMac to boot. _It's one of the old swivel-flatscreen G4's, running OSX 10.4 on (I think) Tiger.__It went into screen saver mode, but when I moved the mouse or used the keyboard it wouldn't bring up the password XXXXX to get back to the main screen._I switched it off, and when switching back on it goes through the grey and blue screens, but before getting to the log-in screen it goes straight to Darwin._I've tried putting it into safe mode, but this just causes it to stay on the grey screen indefinitely, the cd/dvd tray won't open (though there is nothing in it).
HI , this sounds like a Mac HD install issue .

Lets run though some basic repair checks , but firstly we need to get the CD ejected or at least get the tray open to insert the Mac OSX install DVD 1 the latest pone you have that matches your system .

Push and hold eject , on a USB keyboard while powering on the Mac .
Connect the keyboard directly to the Mac not via a hub etc.

Or use a USB mouse and hold the mouse button or left mouse button while powering on the Mac . Connect the Mouse directly to the Mac not via a hub etc.

Reboot the mac , and hold either the eject on the keyboard at least 6 seconds.
or the mouse button down while the machine powers on .

The disk should eject .


You need a USB keyboard :

Boot into Open Firmware and eject If you have a Mac that will not startup properly and has a stuck disc, try booting into Open Firmware by holding down Command, Option, O key and F key during startup. After booting into Open Firmware, type the command eject-cd.

Blue tooth does not kick in till the login window so bluetooth keyboards wont work.


Ok once ejected please read on .

Repair Mac HD , Check Permissions with the OSX Startup volume.

To check for disk errors and possibly fix issues with the Mac HD volume and other Partitions .

Please run a Mac HD drive repair ,
and Repair Permissions of the Mac HD startup volume .

Disk Utility

1 Start from your Mac OS X Install disc: Insert the installation disc, then restart the computer while holding the C key.

2 When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu.
(In Mac OS X 10.4 or later, you must select your language first.)?

Important:- Do not click Continue in the first screen of the Installer.
If you do, you must restart from the disc again to access Disk Utility.

3 Click the First Aid tab.

4 Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.

5 Choose your Mac OS X volume.

6 Click Repair. Disk Utility checks and repairs the disk.

If errors are found please run the check twice .

Report any errors in displayed RED to me .

Tip:- Always start up your computer from an Install or Restore disc when using Disk Utility to verify or repair your startup volume.
**Perform Disk permission repairs while Booted to your Mac HD as normal**.

Please run repairs on all your Mac HD partitions and disks.
Choose in turn the drive name from the left hand list , and use repair .

Run repairs twice if RED errors where found , check to see if they are now cleared.

Using the Repair Privileges Utility

For Mac OS X 10.2 or later, open Disk Utility found in the Applications/Utilities folder.

Select your Mac OS X startup volume in the column on the left of the Disk Utility window, then click the First Aid tab.

Click the Repair Disk Permissions button.

Please wait while the Mac HD is checked.

If errors are found please run the check twice .

Report any errors displayed in RED to me .


Permissions Defined
Mac OS X incorporates a subsystem based on a UNIX-style operating system that uses permissions in the file system.
Every file and folder on your hard disk has an associated set of permissions that determines who can read, write to, or execute it.


Next up system maintenance:

Please try using ONYX to repair clean and check all OSX caches , font caches and other maintenance scripts .

About OnyX
A multifunction utility for Mac OS X.

It allows you to verify the Startup Disk and the structure of its System files, to run misc tasks of system maintenance, to configure the hidden parameters of the Finder, Dock and of some of Apple’s own applications, to delete caches, to remove a certain number of files and folders that may become cumbersome and more. We can also check the SMART status of the HD with OnyX .

Extra tools:


Also its best to get a full disk repair tool for future use :-

Drive genius may have prevent this problem as it seems your Mac HD had an error that needed to be fixed , Apple disk utilities is a basic application not intended for major disk error repairs or testing :-

or drive 10 for OSX depending on OSX version .


Now run some tests with your software and see if there's a difference ?


You can also try this more simple step to try to correct issues :-

Turn off the Mac .

Power on the Mac .

Hold shift on the keyboard using a USB keyboard , while powering on the Mac and booting , boot to safe mode.

Once booted to safe mode , restart and boot as normal .

Full details here :-

This may fix minor issues but it is best to run a Full Mac HD repair from the OSX DVD installer disk , use the OSX disk that goes with your current OSX install ..

Once the Mac HD is tested ok or repaired , you can go on to update the software , please let me know if there are issues ,and give full details. We may need to Archive and install Mac OSX if problems persist and check the Mac hardware is working correctly . And i will give details of how to do that keeping your user account intact if needed.

I hope this helps .

Thanks .
Customer: replied 6 years ago.


sorry, complete beginner question:


Is the install disk the disk with the operating system on (ie: the one I used to install Tiger) or is this something else?

It's getting on to about seven years old now, so it may be a bit of a hunt for all it's original disks.



Thanks for the help, I'll give it a try after 17:00 (UK time) as I'm at work at present.

Hi , no problem thanks for asking .

yes you need the Latest OSX DVD or CD that was used to install OSX on your Mac , if the Mac has never been updated with a second OSX version from DVD , it maybe the OSX install disk that came with the Mac normally disk 1 or maybe marked OSX install disk one etc ..

Does this help ?

Customer: replied 6 years ago.
Hello, The computer won't respond to the eject key, I can open it in Open Firmware however it says "unknown word" when I type Eject-cd
Customer: replied 6 years ago.
I've got tray to open, but it seems to ignore it, starts up, spits disk back out, and just goes into Darwin.
Hi , try holding C on the USB mac keyboard while doing so .

Customer: replied 6 years ago.
I gave this a go, the computer starts up but the screen stays blank. Is there anything else I might be missing?
Hi , sounds like the hardware is not working correctly .

Lets try resetting your Mac's PRAM and NVRAM:

Please follow the full guide for your Mac :-

extra info :-

Contents of PRAM

Some Macintosh computers may not have all the settings described below.

Settings Stored in PRAM :-

Status of AppleTalk
Serial Port Configuration and Port definition
Alarm clock setting
Application font
Serial printer location
Autokey rate
Autokey delay
Speaker volume
Attention (beep) sound
Double-click time
Caret blink time (insertion point rate)
Mouse scaling (mouse speed)
Startup disk
Menu blink count
Monitor depth
32-bit addressing
Virtual memory
RAM disk
Disk cache

Ok, let me know if this helps ?
There is one other reset we can try after this.

Customer: replied 6 years ago.

Thanks, I'll give it a go later today.

Will resetting these lose saved files? I've got some word docs I'd ideally like to recover

Hi , no pram just resets the hardware , and the settings listed in the last post .

The Mac HD is not touched by resetting Pram . .

Thanks .
Customer: replied 6 years ago.
this hasn't worked either, it takes longer to start up, but ultimately the result is the same
Hi ,

OK .

sorry for the delay .

For imac G4 :-
Lets try resetting the PMU to see if this is helping.

The PMU is a microcontroller chip that is present on the logic board in an iMac (Flat Panel). As the name implies, it's responsible for controlling all power functions for the computer such as power on/power off and some aspects of sleep/wake behaviors.

Please let me know how you get on .


Edited by iteachmac on 9/2/2010 at 8:52 PM EST
Customer: replied 6 years ago.
Doesn't seem too relevant to the problem I've got, and I lack a screwdriver for opening it.
Please explain your issue ?

If you cant boot to the install DVD then either the install DVD is damaged or CD DVD drive , or cant load it .

Or your Mac has a hardware fault .

There are only these resets , that can jump start the imac , other than that its ram , swap it out and see if that is an issue . or try re-seating .

Or the internal battery , the battery cell holds the Pram etc.

Is there any thing you can tell me , please explain in full detail as the Mac may be done for .

Do you get chime ?

Do you get Apple logo on boot .?

Can you use an external monitor to test the Mac , is the screen working ?
Screen should be white etc , on power on .

etc .

Unless we can get booted to the install DVD , there are problems other than the Mac OSX install , and possibly both .

Try booting from each of your Mac OSX install disks , if your unsure of the main boot-able install DVD .. , try holding option on boot and choosing to boot from DVD , or hold C on power on keep holding till the computer boots to DVD.

Does the DVD drive spin as to say its loading and booting .??

Also please try safe mode, hold shift key on boot .


Edited by iteachmac on 9/2/2010 at 10:21 PM EST
Customer: replied 6 years ago.

Hya, starting up I get the chime, and it starts up as usual with the apple logo, however once it gets to the stage where normally the log-in screen would load, I get a black screen with white text asking for login details, when provided it logs into the Darwin command prompt.


It still goes to sleep, and wakes up, as per normal. No problems with the power that I can see.

The USB drives still work (or at least, I can connect and charge my iPod, only way of using net at home).


When the boot dvd goes in it makes a whirring sound, and then rejects it.

Customer: replied 6 years ago.
I can use basic commands in Darwin, such as Diskutil, is it possible to repair problems via something like this, or am I reaching a bit?
Customer: replied 6 years ago.
I've managed to run the hardware checking cd that came with it, it's reporting no problems in the memory or on logic board. Can't get it to run any boot DVDs, suspect a problem with the DVD reader... Though doesn't explain the other problems.

Hi ,sorry Iv been away for a few days from Friday .

Will take at look at your replies now.


Please type :- at the command line .

/sbin/fsck -fy , then hit enter .

More info here :-

If you see :-

Please run the same command again until it reads clear ok
** The volume (name_of_volume) appears to be Ok .

/sbin/fsck -fy , then hit enter .

When fsck reports that your volume is OK, please type " reboot " at the command prompt and then press enter.

Hopefully your computer should start up normally and allow you to log in.

Lets hope this fixes the problem .

Edited by iteachmac on 9/5/2010 at 4:28 PM EST
Did you reset the Power management unit PMU?

It may help recover use of the DVD / CD drive .

Customer: replied 6 years ago.
Hya, the fsck doesn't seem to return any info... No errors either, it accepts the command but just does nothing. Haven't reset PMU yet, the cd reader seems to be fine, it's specifically DVDs it is struggling with.
I think the PMU need to be reset , or the problem will remain .

Please can you try to do this , its not too difficult .

This video shows the removal of the lower case , once removed the PMU button can be pressed once , please follow the guide as provided ..


Edited by iteachmac on 9/5/2010 at 5:37 PM EST
iteachmac and 2 other Mac Specialists are ready to help you
Customer: replied 6 years ago.
Reset PMU, no discernible effects.
Can you please try resetting the Pram again once , as below , and then try to boot to th e OSX install DVD holding C on power on , if you have Mac OSX on CD , please try to boot from the CD version.

Please make sure the Mac OSX install DVD is the first disk the "bootable one " , and that it is spotlessly clean , please hold to the light , and wipe with a soft cloth to make sure .

Can you confirm the DVD drive works ? if it does not , it will have to be replaced to fix this issue and possibly a corrupt Mac HD OSX install ..

You can also try the Command line /sbin/fsck -fy , or repairs from diskutils .

Full guide here :-


Edited by iteachmac on 9/5/2010 at 5:56 PM EST
Customer: replied 6 years ago.
Yep, the DVD is definitely playing up. PMU reset isn't changing it. I've got fsck working, will report back soon, it's taking a little while.

Fingers crossed.
Yes it may take a while to complete .

You can also try :-

Use the command line and the command-line utility, diskutil.
  1. Start up your computer and log in as an administrator.
  2. Open Terminal (/Applications/Utilities).
  3. At the prompt, type the following command and then press Return:
  4. diskutil verify /
  5. diskutil repairPermissions /

Edited by iteachmac on 9/5/2010 at 6:09 PM EST
Customer: replied 6 years ago.
No luck, it's still going through the same motions.
Please can you expain the issue with the DVD player , also how do you know it is defective? :)

It maybe best to replace the DVD drive with a better one . The lightscribe is a nice touch on the Samsung .
You can laser label and print lightscribe disks / media . This works in Disc cover software..
User-installable, detailed instructions included

It is very cheap to upgrade the drives days .

If you don't have the required skill to replace the DVD drive , please order the DVD drive from OWC , and ask a local computer shop / tech to install it for a minimal cost .

Otherwise we are stuck in this repetitive loop of fails , we need to archive and install from the install dvd at this point .

If you feel the DVD drive alone to be the reason the OSX install disk will not boot swap out the DVD drive , The Mac HD OSX installation is unrepairable it seems .


Edited by iteachmac on 9/5/2010 at 7:06 PM EST
Customer: replied 6 years ago.
Just a hunch, because it ran the cd for checking the hardware fine, but won't read either boot DVDs, both seem clean and undamaged. The DVD drive is very inside the hub, nearest place I'll be able to get it looked at is apple store. Think I had better bite the bullet and take it to them.
Yes you can do that , of course .

But they wont supply a faster , better light-scribe DVD drive , just a straight replacement .

The DVD drive from OWC will contain instructions to fit , any mechanically skilled individual will be able to fit the DVD drive , though I recommend a repair shop or electrician / TV repair man ..

I hope it works out for the iMac G4.

There is one other option , if you give apple a call , you may be able to order OSX on CD rather than DVD , this may have only been an option for OSX 10.3 however .

Some later iMac G4s can also run OSX 10.5 leopard . 1GHZ CPU or later .

Customer: replied 6 years ago.
I'll see what I can do, I'm out in small villages of UK, good technicians are few and far between :)

A cd version would be ideal if I can find one, though if the DVD player is on it's last legs it may be worth replacing anyway.

thanks for all the help.
Ok , I hope you get some assistance , .

Im in the UK also :)

What area are you in ? and I will try to recommend a company.

Just confirmed OSX 10.4 is available on CD from apple around £15 , read this article , although this OS came out some time ago , Use the contact link to apple if you want to inquire for this CD version explain your DVD version will not load .

You can also show this video to the technician to install the new DVD drive .


The HDD replacement is the same as the DVD drive replacement . .!v=TQ1Y76qfT14&feature=related

Edited by iteachmac on 9/5/2010 at 8:53 PM EST
Customer: replied 6 years ago.
Outside of Cambridge, border of cambs, herts and Bedfordshire.

Brilliant, ta for that :)
Hi , not sure where that is , i know Cambridge is quite an area , Im in Waltham abbey area so i know Cambridge a little.

You could try :-

01223 833 412

Cambridge offices located at:

Lower Court 2
Copley Hill Business Park
CB22 3GN


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