SE/30 Unusual Noise

[Scott Squires]

I picked up an SE/30 off craigslist. It makes a constant buzzing / humming / whining type of noise (having trouble finding the right word to describe it). It didn't sound particularly high-pitched to me, nor was it very quiet, but my roommate could not hear it.

The strange thing is that it mostly stops while the mouse button is held down. (but usually not completely.)

Any ideas as to the cause? Might it be the flyback transformer? Or something else?

 

[drybones99]

It is possible that it is the sound of the flyback transformer, and typically signifies the near-end of its life. If that is the problem, then your flyback doesn't have much more time, and should be replaced, before it burns out, taking other parts with it, as it did to by Mac Plus. On the other hand, old CRTs have a tendency to make a constant high-pitched sound, but the Compact Mac CRTs are too small and in B&W, so they don't produce as high of voltages, and therefore shouldn't make that sound.

 

[Scott Squires]

Yeah, I want to rule out the flyback transformer before I boot it up again.

I found this thread from 1990 that describes a similar situation, but they swapped the entire analog board, which doesn't help narrow it down much. http://www.verycomputer.com/26_6b5fd81c9049534b_1.htm

 

[uniserver]

yeah its flyback,  but make sure to also change all the caps on the AB and PSU too.

http://www.ebay.com/itm/157-026C-Flyback-157026C-Replaces-Apple-HR-42031-/121655780759?hash=item1c533fe597:g:CNUAAOxy14VRWxL3

 

[techknight]

The glue hardens and cracks, causing a loose core. you have to seal the core so it cannot move/vibrate. THAT will fix it. 

 

[Scott Squires]

Techknight, do you have a recommendation for what kind of glue to use? It's always nice to have a repair option, because sooner than later the supply of parts will dry up.

 

[techknight]

Epoxy. Chip off the old white crap that turned brown, and shoot some new epoxy down into the core and the top. Let it dry. DO NOT USE THE FOAM/EXPAND KIND! it will destroy everything. 

The trick is to stop the ferrite core from vibrating. Thats the "ringing" noise you hear, is the physical vibration caused by the constant dwell and reversal of magnetic flux of the windings. 

Thats why every transformer is taped up and sealed as tight as it possibly can be. RIIIIIIIIIIIIIIIIIIIIINNNNNNNNNG....