On Apr 1, 2014, at 2:33 PM, faithie999 <[email protected]> wrote:
> a friend gave me a non-working iMac G5 iSight 17". the symptom: when the > power switch is depressed, the fans (both the optical drive and CPU) come on, > and the front panel pilot light comes on. after 30 or so seconds, the fans > kick into high speed, then intermittently return to normal speed, then high > speed. > > there is no startup chime nor anything on the display. i inspected the > display with a flashlight and there appears to be no image, so i don't think > the problem is the backlight. > > using the excellent iFixit repair guide, i removed the logic board and > checked for bad caps. all the caps look normal. i also checked the power > supply caps and they are normal. > > diagnostic lights on the logic board: > > when the power is connected, led 1 lights as it should. when i press the > power button, led 2 lights as it should. when the cpu overheats and the fans > kick to high speed, led 4 glows red. > > from what i've been able to find online, there is no SMU reset button on this > model. instead, i followed the instructions to reset the SMU by unplugging, > wait 10 sec, then while holding the power switch on, reinsert the power plug. > then release power and depress power again to start. that procedure did not > help. > > finally, i replaced the CMOS battery on the logic board. > > is there anything else i should try before i give up? i hate to throw it > away. > > thanks > > ken > If the third LED comes on, that means the logic board and the LCD are communicating. Since you didn't mention the third LCD, that means they aren't communicating. A red 4th light means the processor is overheating. At this point, about the only things you can try are: 1) connecting an external monitor (if that display lights up with video from the iMac, it means the video circuitry is OK; if not, well, ...); 2) replace thermal pads/paste under all three heat sinks (cpu, gpu, bridge). My experience is that 1) is probably not going to work and that 2) won't make any difference. To paraphrase Steve Jobs' comment about blu-ray, my experience is that G5 iMacs are just "a bag of hurt" and not worth the time and money it takes to make them come back to life. Unfortunately, the next generation of white plastic 17" iMacs with Intel processors isn't much better because of LCD failures. Only when you get to the first aluminum iMacs with Intel Core 2 Duo processors do you find stability and long life in a modern iMac (except for the 24" models with pricey failing video cards). My advice: Harvest the good parts and send that iMac to recycle heaven. Jim Scott -- -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-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] For more options, visit this group at http://groups.google.com/group/g3-5-list --- You received this message because you are subscribed to the Google Groups "G-Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
