Re: trying to revive an iMac G5 iSight 17

2014-04-02 Thread faithie999
thanks.  you were right in assuming that LED 3 did not light.  i assumed 
the worst seeing that there was neither LCD image nor startup chime.

i also failed to mention that i had tried a couple of different memory 
sticks.

i know this is a fool's errand, but there is a mobo on ebay for $30 with a 
couple of bad caps that i will take a flyer on, just to try once more to 
keep this out of the landfill.  since i don't have any history on this 
machine, i can't in good conscience part it out since i can't really test 
anything other than the optical drive and HD.

ken




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Re: trying to revive an iMac G5 iSight 17

2014-04-01 Thread John Callahan
Could be a bad memory chip. FWIW
On Apr 1, 2014, at 5:33 PM, faithie999 faithie...@hotmail.com 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
 
 
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Re: trying to revive an iMac G5 iSight 17

2014-04-01 Thread Jim Scott

On Apr 1, 2014, at 2:33 PM, faithie999 faithie...@hotmail.com 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

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