Why does boot-up fail on the grey-Apple-on-white screen?

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iMac G5

The iMac G5, powered by the PowerPC G5 processor, was originally released in August 2004.

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zischkau @zischkau

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Posted: Aug 26, 2015

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Why does boot-up fail on the grey-Apple-on-white screen?

When my iMac G5 iSight (late 2005, bought new Feb. 2006) stopped booting, it would stall on the 3rd of three white curtains coming down the screen, the one with the Apple in the middle but nothing else. I replaced the 250 GB WD hard drive with a compatible Seagate 1TB drive, which would restart once or twice during the installation process from a 10.5.6 Apple-issued installation CD (or DVD). I could then upgrade to OSX 10.5.7 and 10.5.8. But when I try a cold reboot just using the new hard drive, it fails during boot up on the same screen with the Apple. Seems like the 9-year old hard drive wasn't the problem. What is the problem?

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mayer @mayer

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Posted: Aug 26, 2015

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Open it up and examine the twenty four capacitors for swelling and/or leakage. Observe the diagnostic LEDS in the center of the logic board on boot and let us know your findings.

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Thank you, Mayer. As you often suggest, the capacitors are a problem. The motherboard is the 16-capacitor version, 820-1766-A, and two caps bulged very slightly and leaked. Also checked the Power Supply, Apple P/N 614-0378, and the 1000microfarad capacitor leaked, too. Can't report on the LED's, because when I booted with the bezel off but the display still on, I didn't see any LED's, lit or otherwise, on the MOB (saw the bright LED on the right speaker). Should I replace capacitors now, or is there some way I can find those LED's? Will they show while booting with the display removed?

Sep 6, 2015 by zischkau

The LEDs will show with the bezel. There are probably two CUDA buttons on the logic board to the left of the LEDs. One resets the other restarts. Jim Warholic is the definitive guy on this problem. http://jimwarholic.com/2008/07/how-to-re...

Sep 6, 2015 by mayer

Thanks, I'll study that. Do you also have any advice about videos or readings about how to solder delicate electronic components? Haven't soldered much in 40 years, and I've never used non-leaded solder.

Sep 6, 2015 by zischkau

Right here: Soldering Skills

Sep 6, 2015 by mayer

Spectacluar. Your prior link lead me to some advanced training by JimWarholic. Many thanks.

Sep 6, 2015 by zischkau

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Thank you, Mayer. As you often suggest, the capacitors are a problem. The motherboard is the 16-capacitor version, 820-1766-A, and two caps bulged very slightly and leaked. Also checked the Power Supply, Apple P/N 614-0378, and the 1000microfarad capacitor leaked, too. Can't report on the LED's, because when I booted with the bezel off but the display still on, I didn't see any LED's, lit or otherwise, on the MOB (saw the bright LED on the right speaker). Should I replace capacitors now, or is there some way I can find those LED's? Will they show while booting with the display removed? — zischkau
The LEDs will show with the bezel. There are probably two CUDA buttons on the logic board to the left of the LEDs. One resets the other restarts. Jim Warholic is the definitive guy on this problem. http://jimwarholic.com/2008/07/how-to-re... — mayer
Thanks, I'll study that. Do you also have any advice about videos or readings about how to solder delicate electronic components? Haven't soldered much in 40 years, and I've never used non-leaded solder. — zischkau
Spectacluar. Your prior link lead me to some advanced training by JimWarholic. Many thanks. — zischkau