No chime at start up

Short history of recent problems on my trusty ole iMac.

Six months ago had a OS crash on Tiger. No original install disks so I removed the original 250GB HDD and installed a new WD 640GB HDD successfully.

Now I installed Leopard on this drive. Shortly after this I stated to have KP and freezes.

Then I would have to restart the iMac 2 or 3 times to get it to boot - make the "bong" sound to start up.

At the time I thought it was the on button of the back of the iMac.

This past Saturday I was making a fresh copy of my new drive using TM and an external FW drive and the iMac froze or had a KP.

Went to reboot and no luck. iMac turns on but will not start up with the normal chime or bong. Eventually the fans go into high speed.

God lots of advice from Macresource forums and I decided to replace my PRAM battery.

All went well but it did not help. Same problem.

I did notice two capacitors on the MB with brown spots on the tops. Guess it could be the problem.

I have read reports on what the led lights mean as many people confuse this model with previous models and they are totally different.

Currently my led lights read... led1 comes on and stays on when the iMac is plugged in. led2 comes on when I power up the computer.

I did pull off the power supply and did not see any damage.

I am ready to change out the capacitors on the MB if anyone can confirm that is the problem.

Tahing in advance for any help or support.

I am going to start reading up on this topic some more so I can gear up my mind to take on this repair.

I have a soldering gun but don't know the watts right off hand.

I am new to this site and can not even find where this post is located at. I have to login to my profie to find it.

Almost got scammed today by someone offering me their iMac on crigslist.

So need to come back to reality and fix my own iMac!!!

Thanks

Matthew