Just because the capacitors on the logic board "look fine" doesn't mean they are fine. Bulges prove they are bad, but no bulges don't prove anything. One thing that is known is that if your capacitors have "+" shaped slots on top, they are not the bad lot -- the bad lot all have "K" shaped slots on top. This can also be determined by the serial number ranges for the bad iMacs, which Apple has published.
On this model, if the machine boots as far as yours does, I'd sooner suspect the logic board capacitors than the power supply capacitors. In any event, the 12V lines are mainly used for running mechanicals (hard drive, optical drive) and not logic elements. The problem with buying replacements on eBay is that you never know whether you are buying a unit that is "good," or just one that is "not yet gone bad." There are places that perform whole capacitor transfusions for this model (e.g., http://www.maccetera.com/macstuff/imac_g5.html at $200; http://www.bentleypc.com/shop/imac_g5_bad_capacitors.php at "call to quote," or http://doubleclickittofixit.com/listings/kurt-kaufhold-apple-imac-g5-17″-capacitor-replacement-service-on-w84508tuptlz-by-doubleclickittofxiit/ at $75). You can also buy "kits" online for $25. I tried doing this job myself, ONCE. I found the low-lead solder used by Apple impossible to rework with my "traditional" soldering equipment. I won't attempt this job again. On Jun 2, 2013, at 10:22 AM, H J <heywoodj...@yahoo.com> wrote: > I have very old iMac G5 (2005, non-ALS) that recently died. Symptoms are > either refusing to boot, or booting to desktop and then spontaneously locking > up (non-responsive keyboard and mouse) for no apparent reason. > > According to these articles, > > jimwarholic.com/2008/11/apple-imac-g5-power-supply-issues-and.php > jimwarholic.com/2008/07/how-to-repair-apple-imac-g5.php > > there were known issues with bad capacitors on the MoBo and PSU on this > specific iMac model. I inspected the MoBo and all the capacitors look fine. > That leaves the power supply. > > I can't see inside the cage of the supply without removing it (that requires > a pin-head Phillips screwdriver I don't own), but I did manage to measure the > unloaded voltages on the connector. The 3.3V and 5.0V lines appear fine > (3.32V and 5.08V, respectively), but the 12.0V lines all read 11.8V. As far > as I know this is not obviously a sign of a bad PSU, but neither does it seem > normal -- and the lock-ups I'm seeing could very well be due to under-voltage > on some circuitry. > > My question is, does anyone here have experience with older iMac hardware? > And if so, do you know if the slight undervoltage on the 12V line indicates a > bad supply? I can find replacements on eBay, but I don't want to spend money > on that until I'm reasonably sure that the PSU is the actual problem. > > Thanks in advance, > > -HJ > > _______________________________________________ > MacOSX-talk mailing list > MacOSX-talk@omnigroup.com > http://www.omnigroup.com/mailman/listinfo/macosx-talk _______________________________________________ MacOSX-talk mailing list MacOSX-talk@omnigroup.com http://www.omnigroup.com/mailman/listinfo/macosx-talk
