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starttoday · Dec 9, 2009, 11:13 AM

Hello!

I'm new here, and new(ish) to macs, so I'm confused about a few issues I have... (hopefully I'm posting in the right place!)

I got this machine in September second hand. It was very good, super fast, until I moved house. It then slowed right down (instantly from the 1st time I switched it on in the new house)- to start up there is a blank blue screen for at least a minute, sometimes more. And also now sometimes when I leave it for a while it goes to sleep (which it used to) but now if you leave it to sleep the fan makes a really loud noise and the screen is black, with the white light on the bottom of the monitor slowly going on and off. When it's like this it won't come back on with any amount of moving the mouse or pressing keys on the keyboard, and I just have to press and hold the power switch on the back to switch it off. Even then the fan makes a noise for about 30 seconds after it's off (usually less loud). ALSO sometimes it just won't switch on at all, no matter how many times you press the button or hold it down. I noticed today that this was after it went to sleep and I had to switch it off using the power button, although I had left it for an hour or so- I don't know if there might be any connection there?

I've tried switching it on without the keyboard, mouse or anything else plugged in as I was advised but I've done this a few times and it doesn't help. I don't really know what else to do, being new to macs and not great with computers, so I wondered if anyone would please be able to help?

Thank You, and sorry about such a long post!

Chloe

Big Mac · Dec 9, 2009, 11:33 AM

The fans revving in sleep mode mean you're having a "kernel panic" (like a Windows Blue Screen of Death) in sleep mode. That is not supposed to occur. There is some sort of problem with the computer - either with the OS or the hardware. I would recommend reinstalling OS X - either 10.4 (Tiger) or 10.5 (Leopard). If that doesn't fix the problem then it could be your hard drive or RAM (in the best case) or your logic board (in the worst case).

starttoday · Dec 9, 2009, 02:16 PM

Thank You for your speedy reply! Is there any way for me to reinstall OS X (I've got Leopard) without deleting certain programmes? I have a few microsoft ones (word, powerpoint etc) that I don't have the disks for anymore.

reader50 · Dec 9, 2009, 03:30 PM

When the Install screen comes up, look for an Options button. It will let you choose an "Archive and install" which replaces the OS, but leaves your apps and home folder alone, among other things.

chris v · Dec 10, 2009, 09:23 PM

If this happened right after you moved it, it's possible you could have jared some memory loose in the move.

I recently had an issue with a G5 where when I added some new ram, I jarred 2 of the old banks of RAM loose & when I booted it, the slots showed empty. I had to shut it down, pull the RAM modules out of the first bank & re-seat them to get them to show back up.

It might be worth pulling the RAM out and re-seating it all.

You also might try just pulling out RAM modules (to attempt to eliminate defective ones) if you have more than 2. RAM modules have to be installed in paired in G5's -- if it's a dual-CPU machine with 8 slots, the two inner-most slots are bank one, Like this

4--------
3--------
2--------
1--------

1--------
2--------
3--------
4--------

Hope that makes sense.

starttoday · Dec 11, 2009, 10:26 AM

Thank you all for your replies.

So today I was going to reinstall leopard and the machine wouldn't switch on. I left it unplugged for a couple of hours, it's done this once or twice before but after a minute or two come on. So I scoured the internet (on another computer) and found lots of people having issues like this to do with the battery. After reading that and reading on here, I took the ram out and reinserted it, tried to switch the computer on and nothing happened. Then opened it up again, took the battery out and wiped it, completely dusted the whole inside of the computer and put it back together and it still won't switch on.

Do you think I need a new battery? And if so, is this best to buy from apple?

reader50 · Dec 11, 2009, 10:48 AM

Is this an iMac G5? We've been assuming this is a PowerMac G5 because you posted your question in the PowerMac forum.

Your description sounds more like an iMac G5 with power supply capacitor problems.

anthology123 · Dec 11, 2009, 12:03 PM

You can buy the small 1/2-AA battery from almost anywhere else, places that have computer batteries, otherwise Apple Store may have it.

starttoday · 01:08 PM

Oh gosh sorry i must have posted it in the wrong place. It's an iMac yep, I found this image on google like mine:

Is it best to take it to apple then? I don't have any cover as it's second hand.

tooki · Dec 11, 2009, 12:19 PM

Apple Stores don't carry them, to the best of my knowledge. But Radio Shack does.

reader50 · Dec 11, 2009, 01:12 PM

tooki is talking about the motherboard battery btw, not the iMac.

Your problem sounds like the power supply capacitors have gone bad. This was a problem that plagued some iMac G5s, along with many other electronics made around that time. If so, the solution is to replace the power supply. Does your iMac have the camera above the screen, like in the picture? Or no built-in camera? Those without the camera were much more likely to have received the bad capacitors.

When you put the computer to sleep, the slow-pulse of the power light is normal. Failing to wake up is not normal.

Since this has to do with an iMac, I'm moving the thread to the iMac forum.

starttoday · Dec 11, 2009, 02:43 PM

Hi,

thank you for moving, sorry I put it in the wrong place!

I don't have the camera no, so it seems that bad capacitors are likely the problem! I will look into replacing the power supply. Does this mean the battery, the cable, or something else inside the computer? Sorry I'm so uneducated about this! I can probably take it to the apple store or something to get it repaired if it's difficult.

seanc · Dec 11, 2009, 02:53 PM

I'll chime in here to say that it's probably not worth the money to replace the power supply. I'm in the process of failing to repair mine.

The cheapest I've found them on eBay is £79 for what I believe is a rev. b with ambient light sensor. I'm pretty sure this won't fit a rev. a or c. I dread to think what Apple would ask for!
You also may find that it's actually the capacitors on the logic board - this was my original problem which seems to have killed the power supply. My capacitors in my power supply were fine, I replaced them anyway and am now trying to track down the original issue.

What size is your screen (diagonally) and how fast is the iMac? This can give us some indication of what generation it is.

reader50 · Dec 11, 2009, 02:57 PM

The power supply is a module inside that converts wall-socket power into something more useful to the computer. Replacements cost ~100, assuming you could install it yourself. If you're not handy at such things, then having someone else do it is recommended.

It is at the bottom of the iMac. With the case closed, all you can see of it is the socket for the power cord.

As seanc says, there are other possible causes. It would be good to have someone confirm the power supply is bad before replacing it.

seanc · Dec 11, 2009, 03:15 PM

If it's a revision a, it's really easy to pop the back off.

At least have a scan of the logic board (don't touch anything).
If any of the capacitors aren't flat, you have a problem.

See here for picture reference.
They don't have to be leaking electrolyte, any bulging means it's had it.