Re: 2008 imac won't start

[Jim Scott]

Hi John,

I gave up on “shadetree” BGA reflows years ago, but YMMV. My reflows worked for 
a while, then died for good. 
Another issue with the 2008-era iMacs is that occasionally the “coolant” 
(ether, I’m told) leaks out of the tubes running to and from the fins and the 
heat sink proper. Same problem with G4 iMacs, which also are pretty efficient 
little stationary Hoovers and can choke themselves to overheat death.

Jim Scott, Eureka, CA

> On Mar 30, 2018, at 2:00 PM, 'John Carmonne' via iMac Group 
>  wrote:
> 
> 
> On Mar 30, 2018, at 10:53 AM, Jim Scott wrote:
> 
>> 
>> In the case of your 2008 iMac, in addition to all of the above, the cooling 
>> fins of the heat sink can be clogged by dust, etc. over time as the air 
>> intake vents directly below the card and heat sink assembly are hoovering up 
>> stuff from the desktop. This leads to overheating and eventual failure of 
>> the BGA. Reflowing the BGA doesn’t work because by the time the problem 
>> shows itself, too many of the microscopic traces inside the chip have been 
>> damaged by arcing. That’s why a more permanent repair involves replacing the 
>> chip with a new one. But new chips are hard if not impossible to find, and 
>> my favorite eBay bad chip repair/replace guy refuses to work on those old 
>> iMac video cards because he can’t guarantee a reflow and he can’t obtain new 
>> chips that will work with the card.
>> 
>> Been there, done that a number of times. It’s time to ewaste that iMac, in 
>> my experience.
>> 
>> Jim Scott, Eureka, CA
>> 
> 
> I have recently fixed a number of these iMacs may sound crazy but it worked 
> for me. It's free and at this point you have nothing to lose.
> 
> Take the card off the heat sink and clean all the paste off.
> Pre heat oven to 390 F (pre heat is important)
> Place card on 4 small aluminum foil balls at the corners
> Bake for 7 mins
> Open door and let board cool don't touch it or move it.
> When cool reinstall (don't forget to apply new paste).
> 
> I have also found some with faulty fans so check the fan working before you 
> put it all back together.
> 
> 
> 
> John Carmonne
> Yorba Linda CA
> 92886 USA
> MacPro 2.66 Quad Nehalem
> 

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Re: 2008 imac won't start

['John Carmonne' via iMac Group]

On Mar 30, 2018, at 10:53 AM, Jim Scott wrote:

> 
> In the case of your 2008 iMac, in addition to all of the above, the cooling 
> fins of the heat sink can be clogged by dust, etc. over time as the air 
> intake vents directly below the card and heat sink assembly are hoovering up 
> stuff from the desktop. This leads to overheating and eventual failure of the 
> BGA. Reflowing the BGA doesn’t work because by the time the problem shows 
> itself, too many of the microscopic traces inside the chip have been damaged 
> by arcing. That’s why a more permanent repair involves replacing the chip 
> with a new one. But new chips are hard if not impossible to find, and my 
> favorite eBay bad chip repair/replace guy refuses to work on those old iMac 
> video cards because he can’t guarantee a reflow and he can’t obtain new chips 
> that will work with the card.
> 
> Been there, done that a number of times. It’s time to ewaste that iMac, in my 
> experience.
> 
> Jim Scott, Eureka, CA
> 
 
 I have recently fixed a number of these iMacs may sound crazy but it worked 
for me. It's free and at this point you have nothing to lose.

Take the card off the heat sink and clean all the paste off.
Pre heat oven to 390 F (pre heat is important)
Place card on 4 small aluminum foil balls at the corners
Bake for 7 mins
Open door and let board cool don't touch it or move it.
When cool reinstall (don't forget to apply new paste).

I have also found some with faulty fans so check the fan working before you put 
it all back together.



John Carmonne
Yorba Linda CA
92886 USA
MacPro 2.66 Quad Nehalem






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Re: 2008 imac won't start

[Jim Scott]

It’s the video daughtercard. A bad/faulty/dying video card will thwart boot. 
The RAM card thing makes sense because only one stick makes it easier for the 
EFI boot sequence to progress to a startup chime. Or, there’s a conflict 
between the two sticks that wasn’t apparent until now. Or both. The AHT does 
not detect a faulty video card; it only detects the presence or absence of that 
card. The only way to be certain it’s the video card is to replace it with a 
known good one. Good luck finding one of those today.

iMacs of that vintage are notorious for failing/failed video cards. It’s 
amazing yours lasted this long. The problem is basically the same one that 
affected G3 white iBooks and many G4 iBooks and PowerBooks. Many newer laptops 
made by Apple … and devices made by other manufacturers … also are affected. 
It’s a failing of the solder joints holding the video chip to the board. The 
technique for affixing the hundreds of tiny solder balls to the chip and thence 
to the board is known as BGA or Ball Grid Array. Thus sometimes a video problem 
can be corrected by reflowing the solder. But if the solder is bad, or the 
board flexes (G3 white iBooks, with their 50+ screws holding all the bits and 
pieces together, were notorious for this; the advent of aluminum and plastic 
Unibody cases helped), or too many heat up/cool down cycles are experienced, 
the chip will come loose again anyway. 

In the case of your 2008 iMac, in addition to all of the above, the cooling 
fins of the heat sink can be clogged by dust, etc. over time as the air intake 
vents directly below the card and heat sink assembly are hoovering up stuff 
from the desktop. This leads to overheating and eventual failure of the BGA. 
Reflowing the BGA doesn’t work because by the time the problem shows itself, 
too many of the microscopic traces inside the chip have been damaged by arcing. 
That’s why a more permanent repair involves replacing the chip with a new one. 
But new chips are hard if not impossible to find, and my favorite eBay bad chip 
repair/replace guy refuses to work on those old iMac video cards because he 
can’t guarantee a reflow and he can’t obtain new chips that will work with the 
card.

Been there, done that a number of times. It’s time to ewaste that iMac, in my 
experience.

Jim Scott, Eureka, CA

> On Mar 27, 2018, at 6:11 PM, fishjoy...@gmail.com wrote:
> 
> Thanks for the idea. However, this one (a 24" also) will not boot into Safe 
> mode.
> In fact, I cannot get even a startup chime unless I pull one of the RAM cards 
> out. It doesn't matter whether the left one is in or the right one is in, if 
> I only have one RAM card in, it will produce the startup chime. However, I 
> still have a black screen. 
> 
> I did try to set up an appointment at an Apple store, but since it is 10 
> years old, they would not look at it. 
> 
> A couple of questions:
>   • If it is the video card, does the RAM card thing make any sense?
>   • If the video card was going out, should the Apple Hardware Test have 
> told me that when I ran it last week?
>   • Is there any way to be certain that the problem is the video card?
> Thanks!
> 
> 
> On Tuesday, March 27, 2018 at 8:11:50 AM UTC-6, ValterV wrote:
> Il giorno 27/03/18 03:17, "fishj...@gmail.com" ha scritto: 
> 
> > The machine worked fine for about a week, but today when I tried to wake 
> > it, I got a black and white checked screen. 
> Bummer. That screen makes me think about a damaged video card. 
> 
> I had a similar issue with an Early 2008 24" iMac: red vertical stripes 
> appeared all over the screen (bad video card), and the iMac froze on 
> startup. 
> 
> When I tried to boot in Safe mode, though (hold Shift key during startup), 
> it did boot up. So I thought the video drivers were conflicting with the 
> (now) bad video card, hence the freeze at boot. 
> I disabled all of the drivers, and the iMac would boot fine (although screen 
> redraw was sometimes slow). 
> 
> You can try booting in Safe mode and, if working, you may try my workaround. 
> 
> Here's what I did: 
> - Remove all AMD/ATI kexts in /System/Library/Extensions 
> (it depends on your video card maker and model; mine was ATI Radeon 2600) 
> - Terminal: Touch "System/Library/Extensions" 
> - Delete "System/Library/Caches/com.apple.kext.caches" (in Finder) 
> - Reboot 
> 
> I wrote more details here: 
> http://www.mac-forums.com/apple-desktops/341784-imac-vertical-lines-screen-f 
> rezees-boot.html#post1762659 
> 
> 
> 
> 
> -- 
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Re: 2008 imac won't start

[GMail Valter Psicof]

Il giorno 28/03/18 03:11, "fishjoy...@gmail.com" ha scritto:

> In fact, I cannot get even a startup chime unless I pull one of the RAM
> cards out. 
Ok, so it definitely has some RAM issue.
Maybe a video card issue, too, but of course that comes later.

> It doesn't matter whether the left one is in or the right one is
> in, if I only have one RAM card in, it will produce the startup chime.
If you get the chime with either RAM chip, but not with both, it might be
the RAM itself is fine (although I would test with other RAM modules to be
sure), but the RAM slots and/or controller have issues.

> However, I still have a black screen.
That could depend on a video card issue, or still a RAM issue (e.g. if the
RAM controller is faulty, maybe it pass the first tests but then hangs up
later).

Or, it could be the screen (monitor) is dead, if nothing ever appears on it.
Do you have an external monitor to connect?

>- If it is the video card, does the RAM card thing make any sense?
IMO, there's some issues with the RAM part, regardless of the video card.

>- If the video card was going out, should the Apple Hardware Test have
>told me that when I ran it last week?
Keep in mind AHT is not omniscient: some faults are intermittent, or AHT
cannot detect them all.

>- Is there any way to be certain that the problem is the video card?
Until you solve the RAM issue (so you can boot), I don't think so.

Afterwards, once you are able to boot, you might connect an external monitor
to check whether the issue is video card- or monitor- related.
And you could try my trick to boot into Safe mode to delve deeper.


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Re: 2008 imac won't start

[Julia Brinckloe]

I recall a similar issue I had and I merely replaced the RAM sticks. Also
maxed out the RAM while I was at it. Problem solved.

On Tue, Mar 27, 2018 at 6:11 PM,  wrote:

> Thanks for the idea. However, this one (a 24" also) will not boot into
> Safe mode.
> In fact, I cannot get even a startup chime unless I pull one of the RAM
> cards out. It doesn't matter whether the left one is in or the right one is
> in, if I only have one RAM card in, it will produce the startup chime.
> However, I still have a black screen.
>
> I did try to set up an appointment at an Apple store, but since it is 10
> years old, they would not look at it.
>
> A couple of questions:
>
>- If it is the video card, does the RAM card thing make any sense?
>- If the video card was going out, should the Apple Hardware Test have
>told me that when I ran it last week?
>- Is there any way to be certain that the problem is the video card?
>
> Thanks!
>
> On Tuesday, March 27, 2018 at 8:11:50 AM UTC-6, ValterV wrote:
>>
>> Il giorno 27/03/18 03:17, "fishj...@gmail.com" ha scritto:
>>
>> > The machine worked fine for about a week, but today when I tried to
>> wake
>> > it, I got a black and white checked screen.
>> Bummer. That screen makes me think about a damaged video card.
>>
>> I had a similar issue with an Early 2008 24" iMac: red vertical stripes
>> appeared all over the screen (bad video card), and the iMac froze on
>> startup.
>>
>> When I tried to boot in Safe mode, though (hold Shift key during
>> startup),
>> it did boot up. So I thought the video drivers were conflicting with the
>> (now) bad video card, hence the freeze at boot.
>> I disabled all of the drivers, and the iMac would boot fine (although
>> screen
>> redraw was sometimes slow).
>>
>> You can try booting in Safe mode and, if working, you may try my
>> workaround.
>>
>> Here's what I did:
>> - Remove all AMD/ATI kexts in /System/Library/Extensions
>> (it depends on your video card maker and model; mine was ATI Radeon 2600)
>> - Terminal: Touch "System/Library/Extensions"
>> - Delete "System/Library/Caches/com.apple.kext.caches" (in Finder)
>> - Reboot
>>
>> I wrote more details here:
>> http://www.mac-forums.com/apple-desktops/341784-imac-vertical-lines-screen-f
>>
>> rezees-boot.html#post1762659
>> 
>>
>>
>>
>> --
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Re: 2008 imac won't start

[fishjoyner]

Thanks for the idea. However, this one (a 24" also) will not boot into Safe 
mode.
In fact, I cannot get even a startup chime unless I pull one of the RAM 
cards out. It doesn't matter whether the left one is in or the right one is 
in, if I only have one RAM card in, it will produce the startup chime. 
However, I still have a black screen. 

I did try to set up an appointment at an Apple store, but since it is 10 
years old, they would not look at it. 

A couple of questions:

   - If it is the video card, does the RAM card thing make any sense?
   - If the video card was going out, should the Apple Hardware Test have 
   told me that when I ran it last week?
   - Is there any way to be certain that the problem is the video card?

Thanks!

On Tuesday, March 27, 2018 at 8:11:50 AM UTC-6, ValterV wrote:
>
> Il giorno 27/03/18 03:17, "fishj...@gmail.com " ha scritto: 
>
> > The machine worked fine for about a week, but today when I tried to wake 
> > it, I got a black and white checked screen. 
> Bummer. That screen makes me think about a damaged video card. 
>
> I had a similar issue with an Early 2008 24" iMac: red vertical stripes 
> appeared all over the screen (bad video card), and the iMac froze on 
> startup. 
>
> When I tried to boot in Safe mode, though (hold Shift key during startup), 
> it did boot up. So I thought the video drivers were conflicting with the 
> (now) bad video card, hence the freeze at boot. 
> I disabled all of the drivers, and the iMac would boot fine (although 
> screen 
> redraw was sometimes slow). 
>
> You can try booting in Safe mode and, if working, you may try my 
> workaround. 
>
> Here's what I did: 
> - Remove all AMD/ATI kexts in /System/Library/Extensions 
> (it depends on your video card maker and model; mine was ATI Radeon 2600) 
> - Terminal: Touch "System/Library/Extensions" 
> - Delete "System/Library/Caches/com.apple.kext.caches" (in Finder) 
> - Reboot 
>
> I wrote more details here: 
> http://www.mac-forums.com/apple-desktops/341784-imac-vertical-lines-screen-f 
>
> rezees-boot.html#post1762659 
> 
>  
>
>
>
>

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Re: Digest for imaclist@googlegroups.com - 1 update in 1 topic

[Colin Yarwood]

Buy him an hdmi Monitor and a Raspberry Pi 3!

Sent from my iPhone

> On 30 Mar 2018, at 08:43, imaclist@googlegroups.com wrote:
> 
> 
> imaclist@googlegroups.com Google Groups  
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> iMac G4 700MHz   
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> 
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> > off my computer watching Barney. So, I started installing updates to get to
> > Mac OS X 10.4.11 and use TenForFox, or at least try to get him on Youtube.
>  
> Are you sure that's going to be up to the task? My 1.42 GHz G4 iBook
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> technical side.
>  
>  
> -- 
> [Greg Bennett]
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