Q: Small lines / dots over parts of screen

I had a vertical line which appeared in April 2010 on my iMac G5 isight. I contacted the apple support online, and continued with it even though my computer is off Applecare. Apple responded by calling me at home, and telling me it is fully covered. iMac G5 is back, fixed, free by Apple, and yes, it is a 4.5 yr. old computer which they covered. The display was replaced and everything is working smoothly. Thanks apple! Make sure you give apple the serial number of your iMac. They will take care of this issue.

You are all can see your desktop but not me now... my iMac G5 (1st ver.) is servicing over five years and change the logic board thru the warranty program couple years ago. It looks fine and no big problem after the board changed. But I got the said problem two days ago. All I got the infomation is that the problem will be "fixed" by restart the mac. But the nightmare was now beginning... the screen hang in the "gery apple", and the apple's colour changed!!! (See my album link, "startup" - http://gallery.me.com/leslieli#100003)
I forced shutdown by press-hold the power button, wait for 30mins. and restart it. See the login screen, logged in and see the desktop. But the small lines/dots appeared and increasing.The most strangest thing is the response was very very slow! Whatever the cursor surf in the dock, select a folder, etc... it seems to no response. So I tried restart the mac and the screen is partically blackout and/or strange pattern displayed (See my album link, "desktop" - http://gallery.me.com/leslieli#100003)
There is the last time I can startup the machine "properly" and no hope for restart again, even using safe boot, CD boot...
I opened up the mac and see the back of the mac. I saw six capacitors are broken that located on the left of the mac (See my album link, "inside" - http://gallery.me.com/leslieli#100003). All capacitors next to the CPU heatsink are fine and no breaking feature. I don't know if that six capacitors cause my nightmare but the case is worse than just affect the display.

We have an iMac G5, late 2004, running 10.4.11. It has already had the logic board replaced. A little while back we had the following symptoms:

Fans full on
Short black horizontal lines over whole screen, or pink/green shash rolling through the screen. Also get a little pink box round the OS X countdown timer.
Kernel panic on start up sometimes, or not making it through startup.
Bad smell!

The display disturbance was also present on an external display. After some investigation, I have solved the problem in this case.
I checked the power supply and logic board for bulging capacitors of course, and all A-OK. Inverter board however was not OK, some resistors were burned up and the PCB charred. Replacing this has cured all the problems (and a point to note is, when you replace something, be sure to reset the PMU when you do or you'll get the same symptoms as part of the PSU will be in panic shut down. In this case just whipping out the battery did the job).

Hope this knowledge can help someone who has some or all of these symptoms! We have two 10 year old iMacs whose build quality seems way superior to this G5, which, much as we love it, is the runt of the litter no doubt.

A similar thing has happened to my nearly 5 year old iMac as well. I was getting the same effect and if I moved the mouse it got worse. Then after that the "spinning beach ball" would appear and then nothing else would happen. My computer would slow way down and almost freeze. If I was lucky I could shut down but otherwise it would freeze and I would need to press the power button to shut down the iMac. I tried "letting it rest" and trying again but got the same effect and then the screen went totally blue, then black and I had to force a shut down again.

I would like to keep this computer for at least a year if it's repairable. Does anyone have any luck with this problem? I wonder why my computer would jam up after moving the mouse.

Hey Barry,
The first thing to do is to remove the back and survey the capacitors. Just the tiniest bit of bulging will indicate a bad one.
Re:
http://s291.photobucket.com/albums/ll306/spudnuty/iMac%20G5%20bad%20capacitors/
The ones with the "K" on top are all good. The ones with the "Y" on top are all bad. If you're luck it will only be 4 or so bad.
The other possibility is it has a graphics chip that has gone bad. I've been working on a repair scheme for this problem but no luck so far.

I wonder why my computer would jam up after moving the mouse.

The Mac uses a graphical user interface (GUI):
http://en.wikipedia.org/wiki/Graphicaluserinterface
Any problems (caps or chip) with the graphics section will result in a freeze.
Richard

The day this happened I did open the back to look but it was before I actually saw a photo of bulging capacitors; I had only read about them. I didn't notice anything but maybe I thought it would have been more pronounced than what I saw in the photos you posted. After a few hours I tried the computer again and it worked. I am wondering if it was just overheated. I had not used the computer for about 2 weeks (I had been away on a trip) and I'm guessing the room was pretty hot while I was gone.

Either way I know that I am going to either need to replace the capacitors (something I wouldn't need to get into) or replaced the whole logic board (which Apple does not supply any longer). Both of these endeavors do not sound very appealing to me.

When I first got this iMac G5 it gave me problems. On my own I replaced the logic board. Then later a service tech came to my place and replaced the logic board, which fried the Hard Drive. Then Apple had the computer considered DOA and replaced. 6 months later the keyboard and mouse both stopped working (Thank goodness for Apple Care), then then after another 6 months the CD drive starting ejecting the CDs out (bezel problems). The DVD drive was replaced twice in this machine (with Apple Care) and once by myself. Of course still from time to time it gets over heated and the hair dryer fans will go on. I think that's the last time I ever buy a rev A product. I have learned my lesson. It's the luck of the draw sometimes.

My iPod on the other hand...40GB Click Wheel...what's that? 3rd generation? That thing is still going strong...battery life is great too...Yeah, it looks like a brick compared to the new ipods but it still works so well. ha

Barry,

I thought it would have been more pronounced than what I saw in the photos you posted.

When I judge these, any that are even slightly convex I consider bad. They should be absolutely flat or slightly concave.

I'm guessing the room was pretty hot while I was gone

It would seem to me the temp sensors would have shut the computer down in that case and that would have shown up on the console logs.

Then later a service tech came to my place and replaced the logic board, which fried the Hard Drive.

Hmm don't know how that could have happened. I have much less respect for hard drives after reading:
"Google failure Trends in a Large Disk drive Population"
I'm seeing failures in as short a time as a few months or even new out of the box. Typically less than 3 years which is good since that is the usual warranty period.

I think that's the last time I ever buy a rev A product.

I would consider the 1.6 the original rev A on this machine. These iMacs were particularly plagued by the "capacitor plague". However we had 30 Dells that had the same capacitor problem and they had twice as many capacitors in them as these iMacs. Dell replaced about 2/3rds of them and the rest went into the recycle bin.
"Rev A" - I just heard my first Windows 7 story the other day. My client bought a copy from Tiger Direct and it turned out (or so Microsoft said) to be a development copy. It totally disabled his machine it was completely non recoverable! It had to go in and Tiger Direct had no idea how that happened.
Richard

Richard,

I am not sure why I was having the problems suddenly and then it all went away. I will take the time to pop off the back and confirm whether is any bulging showing or not.

I do have to say that my HD has been used heavily and so far (knock on wood) no problems have happened. I have been using that drive for over 5 years (will be 6 in October I believe).

When I ordered my iMac I had the choice of a 1.6 or 1.8 model. I actually got the largest HD and fastest processor, paid for the upgrade of bluetooth mouse and keyboard as well. I upped the memory to 1GB but later took out of the chips and put in a 1GB chip...but I had to take out one of the 512 chips in order to upgrade. I did this much later or I would have only upgraded to 512MB to begin with...256 was standard on this model all those years ago.

Hi Brother,

i just bought my mac mini 1 month before and happen like this the mon. display uneven small dots.

Does it hardware problem?

Thanks,