iMac G3 help

[TheRetroMacNerd]

So my iMac G3 DV Graphite that I rescued from a trash heap makes a whirring noise when turned on, then the light goes green, then it shuts off after a second. My other iMac G3 (Bondi Blue Revision A) just makes a humming noise when it gets plugged in and no power light, nothing shows up on the screen, nothing. Does any body know what's wrong with these 2 beauties?

 

[Bunsen]

Moved to correct forum.

 

[goncalo]

Hi

I also have this buzzing in all my iMac G3s TL when on stan-by.

It is coming from the Power Supply board and it starts as soon as I plug it to the mains.

Something is vibrating and emitting a high pitch sound that is hard to pinpoint even with the board uncovered.

Maybe a thermal scan could help locate the culprit, I dunno.

Unfortunately, while I have just reassemble one Rev. B, I took no pictures of the board's components.

But I have scanned the reverse of the PS board.

Would love to ear from the electronics wizards in da house.

 

[goncalo]

Another fun fact I have come to know about these iMacs.

Sometimes, after some random operation, it stops working and it just there, buzzing.

You press the power button and it just makes a different buzz while you are pressing it.

You lay it to rest unconnected and in the following day everything is OK - like if it never happened...

What can I say, I just love these colorful, child-like contraptions

 

[goncalo]

Could this be the phenomenon known as “Coil Whine” or “Coil Squeal”?

https://en.wikipedia.org/wiki/Coil_noise

http://www.ukgamingcomputers.co.uk/capacitor-squeal-coil-whine-explained-a-63.html

I’ll try to get some hot glue over the inductor(s) and see if it dampens the noise.