[Andrej]

iMac G5 no iSight 17 1.6GHz
Mac OS X 10.4.8
1.25GB RAM
22GB HD space remaining

My iMac G5 has some weird sleeping problems. Most of the time, I'll go to Sleep, and it'll be fine. But, sometimes, one of the following will happen:

[1] I'll put the iMac to sleep, and when I go to wake it, it shuts itself off and then restarts. This is the most common occurrence and is especially true within the first five or so minutes of using the computer.

[2] I'll put the iMac to sleep, and it'll shut itself off just as it goes into sleep mode. Also within the first five minutes, but not as common.

[3] I'll put the iMac to sleep, and there will be no pulsing backlight, but only a minute later, instead the fan will start whirling and then blast to full speed. This just happened once, but not even close to the first five minutes.

I tried turning on and off other connected devices, and that didn't really help, but once in a while, the iMac would should itself off as a result. Or...! A few times, I grounded myself on a chair about 4 feet away from the computer (this chair was on a rug and a deskspace floormat, no wires (covered obviously) around the legs in any direction for at least 4 inches), and when I grounded myself, the iMac turned itself off while in sleep mode!

These problems only became partially annoying to me back in October, and I have been using this computer for a year. I ran Onyx, and the problems came back shortly afterwards. I moved the cable that the iMac G5 was plugged into to a different spot on the extension cord, and that didn't help. I even unplugged all of the cables coming out of the back of the iMac except the keyboard etc., and that didn't help. I tried using the keyboard to wake up the computer instead of the mouse, and that didn't help. I even booted up off a circa. September/October 2006 backup of my hard drive from an external hard drive, and the problem didn't change.

This issue is increasingly more frequent and hence increasingly more urgently in need of a solution.

Edit on 12/25/2006 at around 9pm edt: I just went to turn on my iMac after it being off for 2 hours, and it refused to turn on, even after connecting the power cord to a different extension cable! I unplugged some Firewire cables and the USB 1.x hub, then replugged them back in, and only then could I turn on the iMac. WTF? Stupid P.O.S.

What's going on with the computer??



(By the way, the verification code in the search page is so stupid!! Who's so worried about spammers searching the forums, especially with how bad the search engine is on these forums? Not to mention, when I do a search and then go back to change my query, I always get the verification code wrong, because I have to use a new one, and the Refresh Image link just reloads the same stupid code!)

[molarszbt18]

Well back up all your data and do a erase and install of the OS. When that is done see if you can replicate the issue again. If not something got corrupt and caused it to sleep. IF it does it again check activity monitor and see if there is an error log. Otherwise bring it to an apple service place or an apple store but they may want you to reproduce the issue so be ready.

[Andrej]

I just did the erase and install without installing any new software, and the problem still exists!!

So, it's not related to any "junk" software that I've installed.

How do I check for an error log in Activity Monitor if the words "error" or "log" do not show up anywhere in the application window or menu items?

Also, we can't afford anything anymore. We don't have AppleCare, and I bet that Apple repairs will kill us in costs of up to $500-$600. I doubt that service repairs are possible for us.

Although at least for any time that I start up the computer, sleep seems to work fine until I shut the computer down. In other words, once sleep works, it seems to stay working, especially after the first 5 minutes. I feel that this information is key.

What can I do in the meantime for hardware checks? Should maybe I switch keyboards and mice? (Edit: No, that didn't work either.) If you want me to check inside the computer, then keep in mind that I have no idea what I'm doing when looking at the internal parts of a computer. So, use picture-like descriptions.

[molarszbt18]

I would think you fit in to this catagory so the repair just might be free
Apple - Support - iMac G5 Repair Extension Program for Video and Power Issues

[Andrej]

That's a negative. My serial number falls under the range W8448xxxxxx, which is not listed under the supported ranges in the document.

Some other potentially key information: If I let my computer go to sleep by itself, then sleep functions correctly. It's when I put it to sleep that it sometimes fails. So, I set energy saver preferences to put the monitor to sleep after 2 minutes (dim the display first) and the hard drive a minute later (3 minutes). Yes, I tried changing the settings to 10 minutes and 10 minutes to see if that fixed the problem, and it did not.

Oh, by the way, I "fixed" the iMac not turning on part... apparently, my iMac hates being connected to my LaCie d2 DVD±RW. (WTF?)

I'm thinking of doing the SMU reset. iMac G5: How to Reset the SMU

Edit: Yes, YES, it WORKS!
So, apparently, neighboring devices must have sent harmonics into the SMU that biased its power signal handling capabilities. The SMU did what it was supposed to do.

Looks like problem solved.

[molarszbt18]

If it comes back then the SMU on the MLB is bad, which means the MLB needs to be replaced

[Andrej]

Damnit, it came back!!

All that I know is I have no idea what an SMU is or what MLB means outside of Major League Baseball. If you guys have some experience on replacing the MLB, then give me a step by step guide for doing it myself if possible. Because there is no way that we can possibly afford AppleCare or anything like that. How do you know that it's a problem with the MLB? Why did the MLB even become bad in the first place?

Oh, and, a new problem: The monitor resets its brightness to lowest brightness if I keep the computer turned off for more than about a few hours.

[Andrej]

[6 days later]

I'm going to ask the questions again, since some of you have deduced (my guess, correctly) that the SMU has failed, but no one has said how they know.

How do you know that it's a problem with the MLB (and what does MLB stand for)? Why did the MLB even become bad in the first place?

Also, I'd like to know how you deduced that the MLB needs to be replaced (and how sure you are of it) and how they replace the MLB.

[Andrej]

All right, well, I think that I know EXACTLY where the problem is.

FIRST, I should direct your attention to a webpage that I found:
Bloated iMac G5 Capacitors #1 photo - John C photos at pbase.com

If you all would look at the two topmost images on that webpage, then notice the letter that is engraved on top of each capacitor in the left photo (an "X") and in the right photo (a "K"). Scroll two thirds down the page, and look for the paragraph that has the following: "They are referring to a failed power supply, which causes the logic board's caps to bloat and causes the computer to not turn on, turn off suddenly, or have video problems. This problem appears to be a combination of the logic boards with the "X" style caps combined with a defect in the early design of the power supplies....I have replaced dozens of "X" caps for this problem, and have yet to see any "K"s leak."

I have confirmed this problem, as there are 5 blown capacitors in my iMac:

Overview (280KB): http://home.gwi.net/~rdf/storage/ima...w/P1050007.jpg
Sideview (more dial-up friendly): http://home.gwi.net/~rdf/storage/ima...w/P1050002.jpg
Macro view (476KB): http://home.gwi.net/~rdf/storage/ima...o/P1050005.jpg

The problem is the installation of faulty "X"-capped capacitors onto my iMac G5. I think that I am entitled to a free replacement as was suggested earlier: Apple - Support - iMac G5 Repair Extension Program for Video and Power Issues

[Andrej]

Well, my iMac came back from repairs. Personal reasons for the delays.

Indeed, they replaced those X-caps with the more modern K-caps. Once again, actual medium-res shots from my computer (I like my pocket camera so much...):

http://home.gwi.net/~rdf/storage/ima...cro/macro1.jpg
http://home.gwi.net/~rdf/storage/ima...cro/macro2.jpg

You can unquestionably make out the letter 'K' on the capacitor on the right in the second shot.
Oh, and when I got my iMac back, I found a fully functional copy of iLife '06 preinstalled! See 'ya guys later!

[Andrej]

[17.5 months later]

Folks, is it normal for (alright, the answer is obviously gonna be 'No'...) The problem is sorta back, I think. I'll put the computer to sleep, the white light will start to shine, and then only sometimes, after maybe 1 second, or maybe 2 seconds, the computer would shut itself off. As described above, the logic board was already replaced.

I've even opened up the back cover a few weeks ago, I didn't see any overcharged capacitors.

Also, less frequently (and this part has been going on for many months, but rarely), whenever I would push my keyboard slider tray back into the desk while the iMac is in the process of being put to sleep via selecting the Sleep option in the Apple Menu, the computer would shut the monitor off, but the fan would not quiet down, the white light would not come on, and after a minute, CPU fan time! Wheeee.

Since Jan. 2007, I've moved, and I've taken my iMac with me.
It's a very windy day, and I have no idea if outside power fluctuations form the wind somehow would somehow affect the iMac. Especially with the ridiculousness of iMac video/power supply complaints I've seen since the G5.

[Andrej]

Another update... even when I put the computer to go to sleep automatically (monitor = 3 min., hard drive = 3 min.), doesn't matter, it turns itself off anyways. Sometimes it takes 0.5 cycles of the white light, other times, 2-5, other times, 12 or so, rarely past.
I don't have the frickin time to go a month without a desktop for repairs, not knowing if I'll get another free logic board replacement. Yet this morning (7:30am), I could put the computer to sleep just fine, several times, and the machine did not shut itself off then.

So, I can't tell if there's a malfunctioning capacitor, or if there's a bad extension cord, or if there's loose wiring, or who knows. I think that I've tried moving the iMac plug to a different outlet, but got the same results. Any other ideas?


Edit 1: Erasing and refreshing my Hard Drive did not really seem to fix the problem.
Right now, I'm thinking that it's a peripheral issue, or possibly WeatherDock, even though WeatherDock isn't the problem.

[Andrej]

Hey folks, I THINK... that I found the problem for this time.

It's the External Hard Drive.

Remember when I had this sudden shut down? http://forums.macnn.com/58/imac-emac...turned-itself/

Well apparently when my iMac tells my External Hard Drive to power down, there is very often a miscommunication that causes my iMac to shut down. Meanwhile, if I keep the External Hard Drive off, and then put the iMac to sleep, then sleep works perfectly fine. At least so far it seems to be that way.

So, that kind of sucks. Oh, and yes, I'm willing to bet that both Firewire ports to which my External is connected will do the same thing.


I had been using the External for regular (hourly) Time Machine backups, but I guess I can just no longer keep the External both on and connected to my iMac to ensure that my iMac goes to sleep normally. Again, so far, sleep seems to be working fine.


So, has something in the External Hard Drive been damaged?? Should I replace the External?? I have been using the damn thing for Time Machine for 8 months now, and I've had the External for maybe 2-3 years. It's an OWC Neptune 160 GB with 2 Firewire ports.

[Andrej]

Well for about 30 hours the problem had gone away temporarily... only temporarily, as I feared (AND KNEW... as it always does), but now things are going from annoying to completely weird.

Anyways, this time, I'm busy on the phone hearing that stupid DSL filter clicking that comes up only once every month or so, and I can never figure out what that is short of the DSL phone line filter. So, I give that a few tugs, move some wires around... and then my iMac just shuts itself off again while in sleep! The computer didn't unplug itself or anything, it's firmly fastened into the outlet (well, extension cord, but same idea). Just great, not, here we go again. So, here are some more trials and errors:

[1] Turned the computer back on while keeping external hard drive off, put the computer to sleep: turned itself off. (!) It wasn't doing this for 30 hours of random use before this, and now it started up again!
[2] Tried it again, same thing.
[3] Turned it on, and noticed that my monitor did a regular flash to all-off during startup, and when my desktop appeared, the monitor was somehow set to minimum brightness. After startup, I unplugged everything but my USB 1.1 hub and my ethernet cable, sleep worked fine. Plugged in all my stuff, sleep worked fine.
[4] So, I turned off the computer, wait 5 seconds, then plugged it back in, let it start up (normal brightness this time, had to adjust it in [3]), then put it to sleep..... and, jeez, how do I explain this one? This time, I went to wake it up, and the keyboard/mouse lit up, but only one fan inside the computer turned on (the quiet one), and the monitor stayed off, and I had to unplug the power cable from the computer to turn it off (could not get it to turn off by holding down the Power button for 6 seconds or longer).

So, once again, I'm back to old-fashioned searching everything in the universe that could contribute to this inappropriate Sleep behavior. Hang tight, I'll need to do yet more troubleshooting. Day 4 of this garbage, and now it's a nightmare.

[Andrej]

Alright, I think that I've finally narrowed it down folks. (YAY ME!)


Apparently, it's a Firewire-Motherboard power interface damage problem.


Alright, let me define three kinds of sleep malfunctions:
Type A: Putting the computer to sleep results in the computer shutting itself off.
Type B: Waking the computer from sleep (generally with a mouse click) shuts the computer off.
Type C: Waking the computer from sleep (often with a mouse) causes the keyboard, mouse, and one fan to become active, but the computer remains otherwise unresponsive.


Alright, here are my tests:
[1] Start up the computer with Firewire cord to DVD±RW to port 1 on computer, putting the computer to sleep results in Type C.
[2] Start up the computer with Firewire cord to DVD±RW to port 2 on computer, putting the computer to sleep results in either Type A or Type B, usually type A.
[3] Keeping nothing connected to the Firewire ports and putting the computer to sleep works fine.
[4] Waking the computer up, then plugging one of the cables in to either port and putting it back to sleep often (but not always) will give me back one of the three times.
[5] There seem to be instances in which having things connected to Firewire will still allow sleep to work normally regardless.


These tests were performed while having my USB 2.0 ports all connected up, including to a USB 2.0 hub.


At this point, I am thus convinced that the freakout that I had with the External Hard Drive damaged the I/O power interface, but only for the Firewire ports.


(I can see why you're all annoyed about me bumping and posting in my own thread like this, but I'm trying like hell here to figure this out, and I think that others can still get a sense of iMac G5 design and possible sources for "power supply" issues beyond the "It's already been replaced" dilema. It's pretty clear that the port design wasn't the best on these computers.)


Oh, and I should mention that in the past 4 days, every single time that I've done a test and had either nothing or only my USB 1.1 w/keyboard connected to the computer, sleep has worked every single time.

This is not a software problem whatsoever, for me at least. But this does appear to be a damaged I/O power thingy... somewhere.

Once again, the problem seems worked around, at least for now, as I've finally gotten a pretty decent idea as to what's causing it. (Time Machine will have to be a once in a while thing for me, I guess.)


Anyone know anything about power anomalies like this??


So, for right now it seems, I'll just plug in my Firewire devices only when I need them.



Edit: Or what I could do is just not use Sleep altogether. I mean, by habit I tend to use it a lot, that's all.

Edit 2: Just more evidence that it's a problem with Firewire. There was a thunderstorm last night, knocked out all the power statewide for a bit in the morning. I had unplugged the computer, so it's all fine. The storm passed a while ago, so I plug in the computer, and... the hard drive tries to spin up, but only for a few light tinsy sounds (as when a CD spins up), and then that's it, no lights or anything. So, I disconnect my external hard drive and DVD±RW from the Firewire ports on my computer, and it starts up fine. Weird!