iMac G4 Dome Reassembly

[christiann]

Hi there. I have never had an iMac G4 before. The G3 is extremely easy to replace parts. However, in the G4, I replaced the internal battery and added an AirPort Extreme card. However, I can’t seem to figure out how to snap the bottom piece of the cover onto the dome/base of the Mac. It will not line up, despite placing everything in the correct spots. It’ll look fine in one spot, then it’s completely open in another. Does anyone know how to close the bottom piece?

-C

 

[CooperBox]

Ah ha! Been there, experienced that! Your problem is that there is a cable trapped, or the 'floating' connector inside the dome (on earlier pre-USB2 models) is not correctly aligned. Whatever you do DON'T put the long bolts in and try to pull the assemblies together. Pull the base away, check all connectors and cables and re-attempt.
The other thing that can cause this is one RAM stick being partially lifted/disengaged.

 

[christiann]

Ah ha! Been there, experienced that! Your problem is that there is a cable trapped, or the 'floating' connector inside the dome (on earlier pre-USB2 models) is not correctly aligned. Whatever you do DON'T put the long bolts in and try to pull the assemblies together. Pull the base away, check all connectors and cables and re-attempt.
The other thing that can cause this is one RAM stick being partially lifted/disengaged.

I checked the RAM and it is in the right spot. It’s the 20” 1.25GHz USB 2.0 model. I did try forcing it to close using the screws . Do you think it will help if I turn it left or right? I can’t tell if the dome is supposed to go over the dome or if it slides under the dome.

 

[CooperBox]

If you tried forcing using the screws I advise you to remove the base completely and double-check for any signs of damage. I hope you haven't damaged anything as those 20" 1.25GHz models are very hard to come by, plus they do not have what I term the 'floating' internal connector and are thus usually far easier to align and install the base.
THIS video at the 9:27 to 9:32 time marker shows how easy it should be to re-assemble the base to the dome.

Fwiw, I cringe when watching this video (not mine) at the 8:09 to 8:32 time marker where the SSD has just been loosely placed onto the HDD carrier without any attempt to secure it in place. There's a high chance at some time when moving the iMac that the SSD or one of it's ribbon connectors will contact the fan, with damage next time the iMac is powered on.
Another to watch at 19:00 time marker, shows assembly should be easy if you have no cables or others features fouling inside.

 

[christiann]

If you tried forcing using the screws I advise you to remove the base completely and double-check for any signs of damage. I hope you haven't damaged anything as those 20" 1.25GHz models are very hard to come by, plus they do not have what I term the 'floating' internal connector and are thus usually far easier to align and install the base.
THIS video at the 9:27 to 9:32 time marker shows how easy it should be to re-assemble the base to the dome.

Fwiw, I cringe when watching this video (not mine) at the 8:09 to 8:32 time marker where the SSD has just been loosely placed onto the HDD carrier without any attempt to secure it in place. There's a high chance at some time when moving the iMac that the SSD or one of it's ribbon connectors will contact the fan, with damage next time the iMac is powered on.
Another to watch at 19:00 time marker, shows assembly should be easy if you have no cables or others features fouling inside.

I saw that one. I will keep trying. It seems like it isn’t damaged.

 

[Ursus1968]

I checked the RAM and it is in the right spot. It’s the 20” 1.25GHz USB 2.0 model. I did try forcing it to close using the screws . Do you think it will help if I turn it left or right? I can’t tell if the dome is supposed to go over the dome or if it slides under the dome.

If I am not mistaken, there are 2 little notches (or whatever it is called) in the 20" dome that you should align to a corresponding hole in the base plate, to make it easier to close the G4. You can see on "hole" in the picture below, to the right of the "10:01" time marked, below the red line. There would a corresponding notch in the dome, plus another pair of nocht+hole on the diametrically opposite of the base plate/dome.

 

[Ursus1968]

If I am not mistaken, there are 2 little notches (or whatever it is called) in the 20" dome that you should align in a corresponding hole in the base plate, that would make it easier to guide. You can see on "hole" in the picture below, to the right of the "10:01" time marked, below the red line. There would a corresponding notch in the dome, plus another pair of nocht+hole on the diametricall opposite of the base plate/dome.

View attachment 1981606

Just checked my disassembled 17" G4, and found the same nothes there as well, see pics below:

 

[christiann]

Just checked my disassembled 17" G4, and found the same nothes there as well, see pics below:

Thank you. I’m still trying to get it closed! I keep lining it up and pushing in but there is always a side that is sticking out with a gap. I have no clue how Apple did it..

 

[Ursus1968]

Thank you. I’m still trying to get it closed! I keep lining it up and pushing in but there is always a side that is sticking out with a gap. I have no clue how Apple did it..

It is tricky, not doubt about it, but as CooperBox noted:, probable culprits are the cables that can get stuck in bad places, so try as much as possible to tuck them away. The video in

shows it pretty good, but to make it work, I start with aligning the bottom notches, then while keeping a bit of pressure there to keep it aligned, I close the upper part. If you dont get it right, I suggest starting over, rather than wiggling to much left or right. What can happen if you do that , is that you put pressure on the RAM, making it to "pop up". Also I want to mention that you must not forget to apply thermal paste on the thermal pipes (the ones in the picture + the ones next to RAM slot)

 

[christiann]

It is tricky, not doubt about it, but as CooperBox noted:, probable culprits are the cables that can get stuck in bad places, so try as much as possible to tuck them away. The video in

shows it pretty good, but to make it work, I start with aligning the bottom notches, then while keeping a bit of pressure there to keep it aligned, I close the upper part. If you dont get it right, I suggest starting over, rather than wiggling to much left or right. What can happen if you do that , is that you put pressure on the RAM, making it to "pop up". Also I want to mentioned that you must not forget to apply thermal paste on the thermal pipes (the ones in the picture + the ones next to RAM slot)
View attachment 1981991

I am going to keep trying
I have no idea why Apple would manufacture a computer so difficult to open!

 

[TzunamiOSX]

I have an iMac, too. Opening is easy and closing also, but be really careful with the cables. It's very easy to pinch the cables if you're not careful.

 

[Amethyst1]

I have no idea why Apple would manufacture a computer so difficult to open!

It is not a computer. It is a piece of art. Meant to be marvelled at, not disassembled.

 

[reddrag0n]

It is not a computer. It is a piece of art. Meant to be marvelled at, not disassembled.

ROFLMAO!!!! thats why my imac is sitting on the floor in my bedroom because i have nothing for it to do.

 

[CooperBox]

I am going to keep trying
I have no idea why Apple would manufacture a computer so difficult to open!

It's really so easy to open, and designed to be equally easy to close if cable management is respected, and the few tips already provided are followed. I'd wager that your problem is cable bundles or single cables incorrectly routed.
Anyway your frustration is felt and my motivation to help find a solution led to me cracking open my own 20" G4 iMac in order to take a few photos:
Lie the iMac down as shown. I've found this is the ideal position to remove the bottom section from the dome and also to reinstall.


Wind out the 4 retaining screws and pull the base away slightly from the top. You should have a view as follows:


Continue to lower the base slightly. Note the vertical positioning of the earth wire (with red ident), also how the green/yellow & black wire bundle and connector slides out easily from the space between optical drive ribbon cable and inner surface of dome. If yours doesn't look exactly like this it's probably the problem area.


Lowering the base even further it should look like this:

Without moving the assembly this is how things should look viewed from the top:
Similar view from top:


Below: When closing up ensure this large connector and cables have a free space to sit into. If that optical drive ribbon cable on the right is not fully seated it will prevent the other cable assy from entering correctly.
Apologies for the greasy finger print on the side of dome (oh the shame).....


Hope some of these may assist. Let me know if more views are required as I've yet to re-apply thermal paste to the heat sink and close up the assembly.

 

[christiann]

It's really so easy to open, and designed to be equally easy to close if cable management is respected, and the few tips already provided are followed. I'd wager that your problem is cable bundles or single cables incorrectly routed.
Anyway your frustration is felt and my motivation to help find a solution led to me cracking open my own 20" G4 iMac in order to take a few photos:
Lie the iMac down as shown. I've found this is the ideal position to remove the bottom section from the dome and also to reinstall.
View attachment 1982487

Wind out the 4 retaining screws and pull the base away slightly from the top. You should have a view as follows:
View attachment 1982489

Continue to lower the base slightly. Note the vertical positioning of the earth wire (with red ident), also how the green/yellow & black wire bundle and connector slides out easily from the space between optical drive ribbon cable and inner surface of dome. If yours doesn't look exactly like this it's probably the problem area.
View attachment 1982490

Lowering the base even further it should look like this:
View attachment 1982491
Without moving the assembly this is how things should look viewed from the top:View attachment 1982499
Similar view from top:
View attachment 1982497

Below: When closing up ensure this large connector and cables have a free space to sit into. If that optical drive ribbon cable on the right is not fully seated it will prevent the other cable assy from entering correctly.
Apologies for the greasy finger print on the side of dome (oh the shame).....
View attachment 1982500

Hope some of these may assist. Let me know if more views are required as I've yet to re-apply thermal paste to the heat sink and close up the assembly.

Thank you SOO MUCH! I am going to leave it open for another day so I can see if the issue is dead PRAM batteries or a dead PSU. Can it boot without the PRAM batteries? I guess I will try learning how to open/close it until they come. I will update you in a bit. I really appreciate it.

 

[CooperBox]

Thank you SOO MUCH! I am going to leave it open for another day so I can see if the issue is dead PRAM batteries or a dead PSU. Can it boot without the PRAM batteries? I guess I will try learning how to open/close it until they come. I will update you in a bit. I really appreciate it.

I thought you said in your first post that you changed the battery........?
My initial thought about the Pram battery is that if dead it shouldn't affect booting. However having just watched one video HERE, it appears that a new battery fixed his non boot problem.

 

[christiann]

I thought you said in your first post that you changed the battery........?
My initial thought about the Pram battery is that if dead it shouldn't affect booting. However having just watched one video HERE, it appears that a new battery fixed his non boot problem.

I bought a used one. I ordered more new ones because I think it was dead.

 

[CooperBox]

I was prompted by SHMBO to get my 'toy' off the bed asap, so before rapidly re-assembling I took these final 2 photos.

Carefully lowering the base as far open as possible (without disconnecting any internal cables) this is how your iMac should look. Note how that black cable and it's in-line connector have been pushed into the top dome assy as far as possible and should stay lodged in that position to aid complete closure.


When you've arranged your cable management as near as possible as shown, I suggest you don't apply thermal paste at this stage, but perform a trial closure. If the base can be closed flush with the dome mating flange, hold it closed and pull down the assy into it's normal operating position. Connect the power cable to the iMac then to wall socket and power on.
Hopefully with the new PRAM battery (having previously confirmed voltage at a healthy 3.6V) it should power on. If it does, then power down (don't keep the iMac running for more than a minute or two without thermal paste applied). Open up and apply paste at locations as shown below. Complete the closure with 4 screws.
If your iMac didn't boot with a new battery, a beep may indicate a problem with RAM modules. With no signs of life, it could well be a defective internal power supply.

 

[christiann]

I was prompted by SHMBO to get my 'toy' off the bed asap, so before rapidly re-assembling I took these final 2 photos.

Carefully lowering the base as far open as possible (without disconnecting any internal cables) this is how your iMac should look. Note how that black cable and it's in-line connector have been pushed into the top dome assy as far as possible and should stay lodged in that position to aid complete closure.
View attachment 1983053

When you've arranged your cable management as near as possible as shown, I suggest you don't apply thermal paste at this stage, but perform a trial closure. If the base can be closed flush with the dome mating flange, hold it closed and pull down the assy into it's normal operating position. Connect the power cable to the iMac then to wall socket and power on.
Hopefully with the new PRAM battery (having previously confirmed voltage at a healthy 3.6V) it should power on. If it does, then power down (don't keep the iMac running for more than a minute or two without thermal paste applied). Open up and apply paste at locations as shown below. Complete the closure with 4 screws.
If your iMac didn't boot with a new battery, a beep may indicate a problem with RAM modules. With no signs of life, it could well be a defective internal power supply.
View attachment 1983054

Ended up returning it.. :/

 

[CooperBox]

Ended up returning it.. :/

If you are returning it I assume that you managed to close it correctly.....? Was this the same iMac that you got for $20? If so the individual parts are worth far more than this, especially for a 20" which are becoming more and more scarce.
Can we assume that the change of Pram battery still didn't provide a cure?

 

[christiann]

If you are returning it I assume that you managed to close it correctly.....? Was this the same iMac that you got for $20? If so the individual parts are worth far more than this, especially for a 20" which are becoming more and more scarce.
Can we assume that the change of Pram battery still didn't provide a cure?

Yes and yes. It was a struggle but I managed to somehow close it. The PRAM battery did not fix the issue. I guess you’re right, I could’ve sold it for parts… but live and learn..

 

[Wild Hare]

Massive thanks to @CooperBox for taking the time and expending the effort to disassemble and photograph his 20” G4 iMac. (Especially with SHMBO’s alert attention.)