[alimunnik]

I awoke this morning to a rising sun and a misbehaving iMac G5 20" (rev. B). Instead of responding instantaneously to my commands I was treated to a virtuoso display of spinning beach balls. The other indicator that not all was well in the Land of Oz were strange static sounds coming from within my recalcitrant machine. Not the first time I heard these, but they had always disappeared within a few minutes.
To remedy the situation I turned the unit off and unplugged the power cord. Half hour later I started it up and was pleased to hear the signature chord chiming in. Then when the "Starting OSX" box appeared, things went awry. Within two seconds and before filling the horizontal bar with blue light, the box disappeared and the screen went blue with the arrow pointer stuck in the upper left corner. And that's the way the screen remained, oblivious to all my efforts to create some kind of response. I have repeated this process several times with the identical result and looks like I cannot progress beyond the blank blue screen.
As luck would have it, today is a civic holiday and the dealer from whom I purchased this unit is closed for the day. I have heard about the Old Testament groans and lamentations concerning lack of quality control on the iMac production line. I have this machine for less than three months and have been lavish in my care. Have any fellow iMac owners out there in Cyberland experienced a similar problem, and can they please enlighten me as to the technical nature of my predicament? Thanks.

[seanc]

It sounds like your capacitors have blown.
If you remove the back of the Imac and have a look inside, check for any bulging capacitors. They should all be completely flat.

You should be able to find out how to remove it in your manuals.

You need to phone Apple and describe the problem, and tell them if there are bulging capacitors. They shouldn't have any problems with you taking the back off as they encourage the user to replace parts themselves and have tried to make it as user friendly as possible.
Apple should send you out a new midplane free of charge, and will provide with you with some documents and information to aid you in the process of returning the faulty board to them.

I beg to differ with all the theories of bad build quality, I don't think the components are to blame, I think it's the case having bad airflow which means the capacitors overheat, start bulging and thus lead to your problems.

If there was a utility to keep the fans running on full blast all the time then I think these problems could be avoided albeit noisy. I could be wrong with my whole theory.

If you have any more questions, just ask

Good Luck,

Sean

[alimunnik]

Thank you, seanc, for your detailed suggestions. I did open the case and all capacitators looked normal.
Also, I have never noticed any excessive heat radiating from the unit. I have subjected it to very light weight use, and I cannot even remember the last time I heard the fan running.
My first suspicions started about a month ago when strange static noises began to appear when I would awake the screen from sleep mode, but these would disappear after a few moments.
I hope my dealer will have some answers for me tomorrow. I am aware of the heat issues, but surely a piece of sophisticated technology should be engineered to operate satisfactorily without necessitating improvised cooling modifications on the part of the user.