Resolved G3: High-pitched noise, only when monitor is ON

[GameX]

Hi,


I've noticed what cause this high-pitched sound I hear when I use my iMac G3 (slot-loading). I couldn't identify the problem first.

It's the monitor that causes this...
I installed SwitchResX for changing the resolution first - The G3 monitor seem to support a maximum of 1024x768. I plugged it to an external monitor (Which support a maximum of 1280x1024), and SwitchRedX allowed to use 1280x1024 with the external monitor.

Choosing this resolution will work with the external screen, and cause the iMac screen to turn Off. And the high-pitched sound is gone!
It's not related to the OS, because it does it during the Apple logo, and on Linux as well, when the monitor is ON.

It's weird... Definitely hardware related, but I can't tell what's wrong (Not worth it to fix it for me, I'm curious about it).

Thanks!

 

[FreakinEurekan]

It's weird... Definitely hardware related, but I can't tell what's wrong (Not worth it to fix it for me, I'm curious about it).

Pretty common symptom of high voltage power supply failing on a CRT display.

 

[GameX]

So if I used a different power-supply (I believe only those from Apple would work!), the problem should be gone, right?

The iMac was unused, left sitting in a shed for 8 years, if that's important to know.

 

[FreakinEurekan]

So if I used a different power-supply (I believe only those from Apple would work!), the problem should be gone, right?

The iMac was unused, left sitting in a shed for 8 years, if that's important to know.

No, it's the internal power supply - the high voltage supply for the CRT, that converts the line power up to 20-30 thousand volts for the picture tube.

 

[GameX]

No, it's the internal power supply - the high voltage supply for the CRT, that converts the line power up to 20-30 thousand volts for the picture tube.

Thank you.

I won't do anything to the iMac, it still work without the sound, when screen is off, connected to another monitor.
Will mark the thread as solved.