Don Lancaster wrote in :


Every once in a while one of these comes up with a back panel singing
inductor that up-the-wall whines.

I tried everything reasonable involving damping the tuning fork like
shield, rubber mounts, etc.
Still could not get the noise acceptably low.

This is apparently a chronic problem that infects a significant number
of 2215's and probably 2213's as well.

Any cures or workarounds out there?


Welll,the original TEK cure(mod) was to clip out the original Triac pre-reg
circuitry and install a separate pre-reg PCB based on a TL494 IC.(also
referred to as OPT.48) I have one of these in my 2213.

TEK also tried a rubber cushion,but it didn't work.

Maybe installing a different inductor would work.

--
Jim Yanik
jyanik-at-kua.net