SE/30 strange radio interference noise

[CharlieFrown]

Hi, I can hear really weird SE/30 sound, like radio interference noise, it corresponds with clicking mouse button, but can also be heard as independent noise without any use of input device. What do you think it is? Motherboard has SMD caps replaced. 

 

[K55]

Se/30's are pretty silent EMF noise wise. Could be a bad flyback transformer or a coil somewhere, those are really the only components that cause whine.

Could also be bad grounding, pop it open and make sure the back is grounded and everything is on correctly.

Always good to have a look at https://tenox.net/docs/misc/The_Dead_Mac_Scrolls.pdf

 

[EvieSigma]

I noticed my SE/30 makes a kind of whining noise for just a second after the chime...what might cause that?

 

[olePigeon]

Could be the flyback.  You can try unplugging the CRT from the analog board so it doesn't power up, see if it still makes the noise when you turn it on.

 

[EvieSigma]

I think the whining noise in my case might be the hard drive, as it doesn't have an electrical sound like a CRT issue would.

 

[CharlieFrown]

ok turning brightness down seems to solve the problem, need to fiddle with cutoff.

 

[Elfen]

It depends on where the whine is coming from.

On the right side around the Floppy drive slot then its more then likely the hard drive.

On the left, then its the transformer, most likely the flyback.

BUT if it in the left rear at the air vent, then it possibly your fan.

You need to listen closely to your machine.

 

[EvieSigma]

Yep, just checked right now and it's the right side. Just a short whine and a sorta "kachunk" noise, which I guess is the drive firing up.

 

[CharlieFrown]

it's back again, random slowndowns, simasimac stripes, non working sound despite new caps! Will try to wash mobo instead of cleaning with IPA, then will try again.