On Apr 16, 2009, at 9:29 AM, owen wrote:
> > I recently upgraded my 1.25ghz G4 iMac with a Pioneer DVR 116DBK and > OSX 1.5.6. I've never had an iLamp open before so I was careful to > clean the thermal pads and apply fresh paste. Since it has run for > almost 5 years continuously it was choked with dust and cat fur, which > I cleaned out thoroughly. The copper tape strips I pulled off the old > drive didn't stick to the new drive very effectively, and one of the > screws crossthreaded and wouldn't go back in very easily. But after I > plugged it back in and rebooted the second time everything worked OK, > and the OS upgrade installed with no problem. > > A couple of days later I noticed the top of the dome was extremely hot > to the touch, and a little while later the computer shut itself down. > I unplugged it and left it overnight. In the morning it was working > just fine, and I noticed the fan running a couple of times. The fan > keeps it only barely warm, when it's running. A day or two later it > started overheating again. and I shut it down overnight (but didn't > unplug it). Now it overheats withing a few hours of use, and the fan > never seems to run. I poked at the fan blades thru the vents and they > move freely but the fan doesn't seem to want to start. > > So, can anybody tell me if this sounds like a bad fan, a bad sensor, > something unplugged, need a new PRAM battery, or what? I would think > the thermal pads are probabaly making good contact or else how does > the metal on top of the dome get so hot? I would open it up and make sure the fan wires are plugged in, and that they haven't gotten pinched so badly they're causing an intermittent ground. It's possible the fan decided to die, but my money is on a wiring problem. Look for pinched/broken insulation and bare wire near metal. It wouldn't hurt to check/replace the PRAM battery, but that's not what is causing the overheating. Whatever you do, don't continue to use the iMac or you will fry the logic board. It sounds as if the thermal paste is doing its job, which is to transfer the heat from the cpu through the heat sink and thermal pipe to the other half of the heat sink and on up to the fan area. There's a good reason (or many) why Apple did not continue that design, not the least of which is the ease with which it's possible to misroute wires/cables and otherwise injure a perfectly good machine. Most people I know who have worked on G4 iMacs absolutely despise having to work on yet another one. It's a perfect case of function being impaired badly by form. -- Jim --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to Low End Mac's iMac List, a group for those using G3, G4, G5, and Intel Core iMacs as well as Apple 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] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/imaclist?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
