Hi folks,
Please remember that no attachments are allowed on LEM lists.
thanks,
Beverly
LEM listnanny
On 8/5/16 9:55 AM, Al Poulin wrote:
Thank you Valter and Scott,
To clarify a couple things. The iMac is an "Early 2009" Display Port, if
that makes any difference. I meant "multiple windows," actually up to
maybe 9 or 10, plus the 30 Desktop icons.
This never happens after shutting down and on a fresh start up. I shut
down maybe a couple times a month to clear cobwebs.
I live in Northern Virginia. There is a Mac repair shop nearby in
Maryland that I could call. I'm not keen on the alternative of lifting
the glass screen off the case myself.
Sample photo attached (I think).
Al Poulin
On Thursday, August 4, 2016 at 10:32:52 PM UTC-4, Jim Scott wrote:
> On Aug 4, 2016, at 5:19 PM, Al Poulin <[email protected]
<javascript:>> wrote:
>
> Greetings,
>
> Am I looking at a hardware problem or misbehaving software?
>
> My workhorse is the last 24 inch iMac that Apple produced.
Running 10.9.5 Mavericks.
> Early 2009 “Display Port”
> 2.66GHz Intel Core 2 Duo
> 4GB RAM
> 640GB HD
> SuperDrive
> NVIDIA GeForce 9400M graphics with 256MB of shared DDR3 memory
>
> When waking from sleep, occasionally the display will scramble
for about 5 or 10 seconds before organizing itself. This seems to
happen more when multiple screens are left open, even as few as
three. Or, it may go black for a few seconds and then settle down.
There are 30 to 35 items on the Desktop.
>
> This has been happening for two or three years, but seems to be
more often now.
>
> If this is hardware, should I eventualIy expect total failure of
the screen to display properly and prevent access to the system?
>
> Thanks,
> Al Poulin
Al,
iMacs of that vintage and screen size tend to develop issues with
the video card, which is plugged into a slot on the logic board and
has a finned heat sink with lots of piping. The card and heat sink
sit at the bottom of the logic board and are directly above the air
intake vents at the bottom of the case. Since the video chip itself
is attached to the card with hundreds of little solder dots (the
notorious BGA or ball grid array), any overheating of the card or
chip can cause one of more of those solder joints to weaken and/or
crack. Thus any accumulation of dust or dust bunnies that blocks the
cooling fins can be bad news for the BGA and thus video performance.
The finned heat sink for the cpu is directly above the video card
heat sink, so there’s an impact on the cpu also if there’s blockage.
I have seen exactly the pixelization you describe as scrambling in
video cards that ultimately fail after many heat up/cool down
cycles. The problem is accelerated dramatically by dust buildup
blockages of the cooling fins.
So, yes, I believe you are experiencing the symptoms of a failing
video card. You can open the case, disassemble things enough to
clean out the dust. But the damage won’t be reversed, although
failure may be delayed by the cleaning. The good news is that the
card can be replaced. The bad news is that new cards are hard to
find and pricey. Used cards also can be hard to find and equally
pricey, and there’s no guarantee that they won’t soon fail too.
I have used a couple of repair services advertised on eBay, with
mixed results. Reflowing the solder joints is a standard approach,
and often restores a card to working order. However, internal arcing
causes damage and a reflowed chip quite often fails again, for good.
Thus I no longer ask for a reflow. Rather, I pay a few more dollars
(@ $150 or so) and get a brand new video chip installed. New chips
come complete with the BGA solder balls, which makes removal or the
old chip and installation of a new one a breeze for someone with a
high end work station and the training and experience.
However, it’s getting more and more difficult to find a repair
service that has the proper replacement chips. So you’ll have to do
a lot of digging to find a vendor who not only has the correct video
chip for your Late 2009 A1225 24” iMac, but also is willing to do
the repair on a card that’s already exhibiting symptoms. Go into
About This Mac and determine exactly which of the three video cards
available in your model has been installed. Then go looking for a
vendor who has that chip in stock and will install it. I have found
eBay vendor/seller brickfence (he’s in the L.A. area) to be highly
reliable, honest and easy to deal with during multiple transactions
over several years. But there are lots of others, so do careful
shopping and check their feedback.
Jim Scott
Eureka, CA
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