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iMac G4 USB not working? (pls help)

roadbloc

roadbloc

macrumors G3
Original poster
Aug 24, 2009
8,784
215
UK
I decided to change the hard drive in my G4. Unfortunately, the hard drive is like at the top of the machine, and since access to the insides starts at the bottom, I had to take pretty much everything out before being able to replace it. I followed this guide and things seemed to go smoothly.

When I next switched it on, the iMac bonged okay and came up with the question mark finder folder, which basically means I need to reinstall the Operating System. However whenever I tried to eject the disc drive, nothing appears to happen. First I thought it was because I was using wireless peripherals, but even now with a wired keyboard, I cannot get the disc drive to open. I've tried the option (alt) key, C and F12, none have worked. The most disturbing thing I've noticed however, is my wired USB keyboard doesn't even appear to be powering. Caps Lock key displays no light and I have no way of telling if USB is even working at all.

Have I messed up my USB with my hard drive replacement? And if so, how have I managed this and what should I do?

(TL;DR - I replaced the hard drive in my iMac G4, but may have also ruined USB whilst doing so. Any help appreciated.) :)
 
I bought an iMac G4 last year, upon putting an install disk in that it refused to read, it wouldn't eject it - even under open firmware, nothing worked. I had to gently force the tray open and turn the mechanism cogs with a penknife - after that I tend to use an external drive.
If you try open firmware commands at least that'll tell you if your ports are functioning.
 
Dronecatcher said:
I bought an iMac G4 last year, upon putting an install disk in that it refused to read, it wouldn't eject it - even under open firmware, nothing worked. I had to gently force the tray open and turn the mechanism cogs with a penknife - after that I tend to use an external drive.
If you try open firmware commands at least that'll tell you if your ports are functioning.
Click to expand...
Just tried booting into open firmware... Doesn't work. Guess it is my usb afterall. I'm going to open it back up tomorrow morning and see if I can spot anything obvious that's wrong.
 
roadbloc said:
Just tried booting into open firmware... Doesn't work. Guess it is my usb afterall. I'm going to open it back up tomorrow morning and see if I can spot anything obvious that's wrong.
Click to expand...

These G4's are certainly not the easiest or the nicest to work inside. I've now stripped/rebuilt five, including changes of HD and optical drive. Each time I thought, "This will be easier this time", but it never seems to be. There's also some internal differences between 15, 17 and 20" models. If you don't have a model with bluetooth, don't be alarmed at the redundant black bluetooth connector, which is just 'stowed'.
My guess is that you may have forgotten a connector, or (depending on the model) you may not have achieved correct alignment of the pins on that interface connector. I always take a dozen or so photos each time I do a refurbishment, which has often helped me afterwards for troubleshooting etc. Methinks it's breakdown time again to check for an obvious problem.
Interested to hear what you find.

PS: Just had a thought. When you opened the base, did you leave it suspended partially open restrained by the wiring harness, or did you spend an extra 2-3mins to disconnect all wiring to allow the base to be removed completely? If the former, you may have damaged one or more of the smaller wires.
Note:- I still think it's surprising that iFixit still make no official mention of re-applying thermal paste to the heat-sink location. This too varies according to the model type.
 
Last edited:
CooperBox said:
These G4's are certainly not the easiest or the nicest to work inside. I've now stripped/rebuilt five, including changes of HD and optical drive. Each time I thought, "This will be easier this time", but it never seems to be. There's also some internal differences between 15, 17 and 20" models. If you don't have a model with bluetooth, don't be alarmed at the redundant black bluetooth connector, which is just 'stowed'.
My guess is that you may have forgotten a connector, or (depending on the model) you may not have achieved correct alignment of the pins on that interface connector. I always take a dozen or so photos each time I do a refurbishment, which has often helped me afterwards for troubleshooting etc. Methinks it's breakdown time again to check for an obvious problem.
Interested to hear what you find.
Click to expand...
Cracked it back open this morning. Couldn't find anything out of the ordinary, all cables appear to be connected to what I'm assuming are the correct ports. I'll upload some photos for people to take a look at.

PS: Just had a thought. When you opened the base, did you leave it suspended partially open restrained by the wiring harness, or did you spend an extra 2-3mins to disconnect all wiring to allow the base to be removed completely? If the former, you may have damaged one or more of the smaller wires.
Note:- I still think it's surprising that iFixit still make no official mention of re-applying thermal paste to the heat-sink location. This too varies according to the model type.
Click to expand...
I just sort of let the cables hang, but I couldn't see any damage when I opened it back up this morning. Also- thermal paste? Is this something that needs to be done?
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Last edited:
roadbloc said:
Cracked it back open this morning. Couldn't find anything out of the ordinary, all cables appear to be connected to what I'm assuming are the correct ports. I'll upload some photos for people to take a look at.


I just sort of let the cables hang, but I couldn't see any damage when I opened it back up this morning. Also- thermal paste? Is this something that needs to be done?
Click to expand...

Yes definitely - it gets hot in there! After cleaning the surfaces with Alcohol 90% (I get a small bottle from the pharmacy), simply apply a thin layer of thermal compound. Easy.
I'll see if I can find a photo of the exact location to paste, or:-
Check out the YouTube clip 'How to upgrade RAM and change the thermal paste in an iMac G4'. That's not me by the way, and although informative imho it's a little bit 'long-winded'.
(From memory one iMac G4 model has two similar locations which require thermal paste).
 
Last edited:
CooperBox said:
Yes definitely - it gets hot in there! After cleaning the surfaces with Alcohol 90% (I get a small bottle from the pharmacy), simply apply a thin layer of thermal compound. Easy.
I'll see if I can find a photo of the exact location to paste, or:-
Check out the YouTube clip 'How to upgrade RAM and change the thermal paste in an iMac G4'. That's not me by the way, and although informative imho it's a little bit 'long-winded'.
(From memory one iMac G4 model has two similar locations which require thermal paste).
Click to expand...

Thanks! I'll check out that video tomorrow and get it done ASAP. As for my USB troubles, its looking to me as though I should force open the disc tray and see if I have any luck with it once booted into an OS.

Will keep y'all informed. :)
 
MacCubed said:
Is the force eject hole on the DVD drive accessible? If so you could try opening it that way
Click to expand...

Your comment just reminded me of something.
I once wanted to force eject the Optical Drive tray on an iMac G4 (Can't recall what model). Obviously no problem opening the 'smiley-window' from the top using finger nail, but then with the long tail of a paper clip, could not find anywhere that would release the internal latch mechansim. I must have tried for at least 5mins or so. On that occasion I went ahead to open up the iMac in order to clean/refurbish internals, so didn't give much more thought to the tray manual mechanism. Until now.
Thought I would perform a few checks on the 3 iMacs I have on display, a 15", 17' and 20".

The following photo on left shows the 15". A fairly light push on the paper-clip as shown released the CD without any problem. Note the white colour of the manual eject catch.
Photo on the right is the 20" iMac. Note the black colour of the manual eject catch. Pushing hard on this with the 'tail' of the paper-clip failed to release the tray. I then tried with the other end which allows for extra pressure to be exerted. A firm, hard push released the manual eject catch, and the tray opened.
Imac-15-eject-ok.jpg iMac-20'-eject-ok.jpg

I then tried the same exercise on the 17".
Note there is no similar release catch 'window' on this particular optical drive. I spent several minutes probing along the length of that lower slot using both ends of the paper-clip. I was unable to open this tray manually.
iMac-17'-eject-No.jpg


I'm unsure if the optical drive in this particular 17" is original. Pretty sure it's original in the 20".
Hope this may be of some assistance for info purposes.
 
I'd pull out and reseat every connector that can be gotten to while it's apart. Also - as already mentioned - don't put it together without cleaning and re-applying thermal paste in the proper spots.
 
As a double-check, inspect that black interface connector to ensure that there is not a pin pushed back or misaligned. (From a photo I took, it looks like a few of those 26 pin sockets may be redundant).
The connector should be 'floating' on it's two retaining bolts, which allows for slight movement and easier 'blind' alignment when you connect the base unit. Ensure that the two bolts are not tight, and that the connector has free play.
Shown below:

iMac-inside.jpg
 
Thank you for your replies everyone. Armed with this new info I'm going to have another attempt at getting it working today. Will let y'all know how it goes. :)
 
Would like to start off by thanking everyone who helped me in this thread. I think I have everything fixed now.

I cracked it open once more this morning and reconnected all the ports just to make sure nothing was loose or incorrectly plugged. I also spotted the button used to open the disc tray manually. Once everything was double checked and re-plugged, I manually ejected the disc tray and inserted my Tiger install disc. Amazingly, with a disc in, the keyboard appeared to work and the option (alt) key brought up an Open Firmware password prompt. After a few moments trying to remember the password, I managed to get the installation media to boot. :D

http://imgur.com/a/85ik9 <--- here are some photos.

Will mark this thread as resolved if the install completes successfully, which it's looking like it is going to do.

Big thanks to everyone who posted in here. You've all been a huge help. :D
 
fhall1 said:
Nice, hopefully it goes through the entire install. Enquiring minds want to know - did you apply the new thermal paste?
Click to expand...

Not yet... Its on order. I won't be using the iMac until I apply it.

Install completed successfully though so it looks like everything else is okay. Thanks once again for the help guys. :)
 
I do realise that this thread is from 2016, but I have a similar problem. I have too recently opened up my 17” iMac g4 to change the HD (I ended up not changing it) but when I put everything back the USB port works except for any form of USB drive/ external hard drive. I assumed I must’ve forgotten to plug in a cable or something so I took it apart again and I found no fault. But the same error came up. I’m not sure what to do as I cannot transfer any files onto this Mac except using FireWire with another mbp.
 
You state, "but when I put everything back the USB port works except for any form of USB drive/ external hard drive."
You use the word port in the singular, but as you have 3, do the other 2 also fail to recognize external drives? Do they recognize the presence of a keyboard or a mouse? If the answer is negative, you may have pinched a cable whilst re-installing the lower housing, or have a pin pushed-back or misaligned within one of the connectors that you removed from the HD/optical drive assembly.
Is the external hard drive one that you've used successfully before with this same iMac?
Some internal photos could be useful to assist in futher understanding.
 
CooperBox said:
You state, "but when I put everything back the USB port works except for any form of USB drive/ external hard drive."
You use the word port in the singular, but as you have 3, do the other 2 also fail to recognize external drives? Do they recognize the presence of a keyboard or a mouse? If the answer is negative, you may have pinched a cable whilst re-installing the lower housing, or have a pin pushed-back or misaligned within one of the connectors that you removed from the HD/optical drive assembly.
Is the external hard drive one that you've used successfully before with this same iMac?
Some internal photos could be useful to assist in futher understanding.
Click to expand...
Hello,
I have completely forgotten about leaving this comment! Anyway thanks for the reply, the problem still hasn’t been solved. I am planning to restart this project soon and it led me back here.

Out of the 3 ports, plugging a usb drive/external HD into any of them gives the same message: “you have inserted a disk containing no volumes that Mac OS X can read…”. Same goes for the two usb ports on the keyboard. The keyboard and mouse work fine. All of the tested drives work on other Macs. Before I took the imac apart, I was able to use the exact same drives with this exact iMac normally.

once I start taking it apart I will send some pictures of the interior, and I will check pins and connectors as you have mentioned.

Thanks in advance!
 
The obvious questions are:
i) Which 17" do you have. There were 3 versions which don't all run the same OS.
ii) How is the USB drive/external HD formatted? Does the external drive have an OS installed? If so which, and what OS is actually installed and functioning on the iMac, 10.4.11 or 10.5.8?

However re-reading your post ,especially, "All of the tested drives work on other Macs. Before I took the imac apart, I was able to use the exact same drives with this exact iMac normally", worries me and may point to a hardware problem rather than software.
 
I worry the same thing :( I may have accidentally broken something inside?

answers for your questions;
i) I have the 1.25 GHz version
ii) i don’t know about the usb (will check) but the external HD is Mac OS journaled
ii) first release of jaguar, so 10.3
 
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