[X4U] How can you diagnose a power supply problem?

Randy B. Singer randy at macattorney.com
Thu Jan 13 23:58:58 PST 2011

On Nov 23, 2010, at 7:40 AM, Mark Des Cotes wrote:

> Could it be that the PS has enough juice to run the fans & light  
> but not the HD or optical drive? I thought that when a PS went  
> nothing wold work.

Power supplies are known for going bad in G5's, but usually they  
result in a stone dead Mac.

Try this.  (It is a cheap and easy thing to try.)  Replace the PRAM  
battery with a brand new one.  Open your Mac first, and check to see  
if there is a coin cell battery on the motherboard, or a 1/2AA.

Most G5's have a coin cell Lithium battery 922-6476.  There is one in:
     * Mac Mini ALL
     * iMac G5 ALL
     * Power Mac G5 (Late 2005) Single 2.0, Single 2.3, Dual 2.5
     * Power Mac G5 (Late 2004) (Single 1.8 Ghz) (600MHz System Bus)
     * Mac Pro Towers ALL

Almost all other modern Macs uses a 1/2AA lithium battery which you  
can get for about $4 here:

Coin Cell 3v Lithium -  922-6476, more commonly known as a:
Panasonic CR2032

Available for $5 from any Radio Shack

You can get one for even less in the jewelry department of any WalMart.

Randy B. Singer
Co-author of The Macintosh Bible (4th, 5th, and 6th editions)

Macintosh OS X Routine Maintenance

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