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From: Jolly Roger on 11 Jul 2010 09:37
In article <51W5y0sPNk52-pn2-Md0MdV9i1jsd(a)localhost>,
"John Varela" <newlamps(a)verizon.net> wrote:

> On Wed, 7 Jul 2010 20:54:01 UTC, "John Varela"
> <newlamps(a)verizon.net> wrote:
>
> The Apple tech said that when he ran the computer from his disk he
> found no problems. He concluded that there was no hardware problem
> so it must be software so suggested I reinstall the OS.
>
> Meanwhile, from the moment I brought the computer to the Genius Bar
> the on/off switch on the back of the machine started exhibiting a
> new problem: the power button had to be pressed many times before
> the system would finally power up. The tech said he couldn't replace
> the switch, only the whole back plate, and that would cost over
> $200.
>
> So I brought it home. It's been working for a couple of days. The
> on/off switch performs normally. Firewire and Time Machine work. No
> problem with kernel panic after going to sleep because it will not
> go to sleep; it sleeps for only a few seconds, then pops back to
> life. We can live with that.
>
> If serious problems recur I'll try reinstalling OS X but I don't
> think that's where the problem lies. I believe we have a transient
> hardware problem in the power supply.

Ummm... Is it just me, or does that seem to indicate a hardware issue
with (drum roll) power management, which is exactly what you're having
problems with regarding the original sleep problem? Hello, Apple
"genius"?!

Anyhow, I just realized we are talking about an iMac G5. You should be
aware that the iMac G5 was manufactured during the bad capacitor plague,
and will almost certainly have capacitors both on the motherboard and
within the power supply that will eventually fail.

<http://en.wikipedia.org/wiki/Capacitor_plague>

I have encountered and repaired several iMac G5s with this issue by
replacing bad caps on the motherboards and replacing power supplies that
burnt out due to bad caps.

It's quite possible the power issues you are experiencing are due to a
power supply and/or motherboard that is failing due to bad caps. If this
is the case, you can expect the problems to gradually get worse until
the machine just stops working one day when one or more caps explode or
completely fail - either silently, or with a little hiss and puff of
fumes.

As I mentioned, you can repair the bad caps in these machines. To
determine if your machine has bad caps would require you (or someone
else) to open the computer up and look at the capacitors on the
motherboard and in the power supply. Any capacitors that are faulty will
be slightly bulging on the top where the creases (vents) are. They are
usually fairly easy to spot, and there are usually multiple caps showing
signs of bulging. These caps will eventually explode or vent - it's only
a matter of time and heat.

For around $85, http://badcaps.net will replace all bad caps on your
iMac G5 motherboard with good caps. And if the power supply is failing
or fried, you can replace it with a refurbished one for around $100.
Whether it is worth the cost of repair is something only you can decide.
Let me know if you want more information.

--
Send responses to the relevant news group rather than email to me.
E-mail sent to this address may be devoured by my very hungry SPAM
filter. Due to Google's refusal to prevent spammers from posting
messages through their servers, I often ignore posts from Google
Groups. Use a real news client if you want me to see your posts.

JR
From: John Varela on 11 Jul 2010 19:35
On Sun, 11 Jul 2010 13:37:43 UTC, Jolly Roger <jollyroger(a)pobox.com>
wrote:

> To determine if your machine has bad caps would require you (or someone
> else) to open the computer up and look at the capacitors on the
> motherboard and in the power supply.

You remind me that the first thing the Genius did was take it into
the back room to open it up and inspect the capacitors. I just now
popped it open and all the capacitors look good to me.

However, my guess it that a capacitor (or something) in the power
supply is going bad but not yet showing external symptoms.

> Let me know if you want more information.

Thanks.

Except for that peculiar refusal-to-sleep business the computer is
working perfectly. My wife can continue to use it until its status
changes, at which time we'll have to see what's what.

--
John Varela
From: Jolly Roger on 11 Jul 2010 21:14
"John Varela" <newlamps(a)verizon.net> wrote:
> On Sun, 11 Jul 2010 13:37:43 UTC, Jolly Roger <jollyroger(a)pobox.com>
> wrote:
>
>> To determine if your machine has bad caps would require you (or
> > someone
>> else) to open the computer up and look at the capacitors on the
>> motherboard and in the power supply.
>
> You remind me that the first thing the Genius did was take it into
> the back room to open it up and inspect the capacitors. I just now
> popped it open and all the capacitors look good to me.
>
> However, my guess it that a capacitor (or something) in the power
> supply is going bad but not yet showing external symptoms.
>
>> Let me know if you want more information.
>
> Thanks.
>
> Except for that peculiar refusal-to-sleep business the computer is
> working perfectly. My wife can continue to use it until its status
> changes, at which time we'll have to see what's what.

That's probably best. It's hard to tell whether the caps in the power
supply are going bad without removing the power supply and opening it
up.

--
Posted from my iPhone.
From: John Varela on 27 Jul 2010 15:16
On Mon, 12 Jul 2010 01:14:44 UTC, Jolly Roger <jollyroger(a)pobox.com>
wrote:

> > Except for that peculiar refusal-to-sleep business the computer is
> > working perfectly. My wife can continue to use it until its status
> > changes, at which time we'll have to see what's what.
>
> That's probably best. It's hard to tell whether the caps in the power
> supply are going bad without removing the power supply and opening it
> up.

Conclusion:

The problems recur. Resetting the SMU clears everything but the
refusal to sleep. Within a day or two the problems return.

I am using this as an excuse to buy myself a refurbished 27" iMac
and pass my 17" Intel down to my wife.

It'll be a shame to junk a mostly-working G5 but I don't know what
else to do with it. Maybe I'll advertise it as-is (after purging the
drive, of course) on Craig's List. I doubt I'll find any takers.
Anyone here want it? It's in Northern Virginia.

--
John Varela
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