Scott, Valter,
Thanks for reminding me. I have used Target Disk Mode via Firewire. I have a “Late 2013” MacBook Pro, 13” Retina, with Thunderbolt. I understand I can connect to the old iMac via a Thunderbolt to FireWire Adapter. Perhaps I’d have to put a FireWire extension cable in line. http://www.macobserver.com/tmo/answers/how-to-use-target-disk-mode-to-boot-from-another-macs-hard-drive Would that work? With that $30 adaptor it would also be neat to transfer files back and forth. Al On Friday, August 5, 2016 at 2:00:26 PM UTC-4, Jim Scott wrote: > > Al, > > Yes, my mistake. It’s an Early (note “Late”) 2009 A1225 iMac. That makes > no difference in my comments. Thanks for the “illegal” photo. Yep, that’s a > video card issue. > > As you’re not eager to go inside your iMac, I suggest you ask the local > Mac shop how much they would charge to diagnose your iMac using Apple > diagnostic software (Apple Service Diagnostics 3S132, both OS and EFI test > modes) to confirm the video card issue. If the card is the issue, then the > shop will have to remove the logic board in order to replace the card or > have it repaired. That is the perfect time to clean out all the dust as > well as check/replace the clock battery. If the iMac passes the tests, I > still would have the iMac cleaned out inside. It also wouldn’t hurt to > replace the clock battery (CR2032) as well as pull the RAM sticks, clean > their contacts, then reinstall them. > > I’ve been inside lots of Macs, and I’m always amazed at how much dust is > inside, especially units like yours that are infrequently restarted. > > IIRC, Mavericks is one of the recent versions of OS X that relaunches all > apps that were running before a shutdown or going to sleep. As you note, > the more windows you have open, the more noticeable the problem. You may > have a memory leak that forces the iMac to struggle to relaunch all the > windows correctly, but my money is on a dying video card that has one or > more solder joints that open when warm but are closed when the machine is > cold. > > If you’ve got another Mac and can connect them with a Firewire cable, > Valter’s suggestion that you start your 24” iMac in Firewire Target Disk > Mode and then start the other Mac and select the 24” iMac’s hard drive as > the boot disk by holding down the Option key to launch the Picker is a good > way to isolate the hardware/software issue. You will have to let the two > machines run for a while, most likely. If the video issue occurs on the > “new” Mac’s screen, then it’s software; if it doesn’t, then it’s the 24” > iMac’s hardware. > > Good luck. > > Jim Scott > > > On Aug 5, 2016, at 6:55 AM, Al Poulin <[email protected] <javascript:>> > 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]> 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 > > > > -- > > You received this message because you are a member of the iMac Group, a > group for those using Apple iMacs and eMacs. > > The list FAQ is at http://lowendmac.com/imac/list.shtml and our > netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml > > To post to this group, send email to [email protected] > <javascript:> > > To leave this group, send email to [email protected] > <javascript:> > > For more options, visit this group at > http://groups.google.com/group/imaclist > > > > --- > > You received this message because you are subscribed to the Google > Groups "iMac Group" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to [email protected] <javascript:>. > > For more options, visit https://groups.google.com/d/optout. > > <IMG_1553.JPG> > > -- You received this message because you are a member of the iMac Group, a group for those using Apple iMacs and eMacs. 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