Arfa Daily schreef:

This is a *very* common problem on hifi's using a rotary encoder for control
of volume. It is caused by the grease that is put in the shaft bearing to
give it that "stirring treacle" feel, migrating down into the control body,
and contaminating the encoder disc and its pickup fingers.

It is usually a straightforward job to remove the control (two metal tabs
and three pins), bend open the four metal tangs that hold the control
closed, and clean it out. If you use electronics grade isopropyl alcohol on
a cotton tip to deal with the contact fingers, it will usually cause the
grease to 'ball', which makes it easy to remove from them with tweezers or a
pin. Take care with the contacts, as they are quite delicate.The encoder
disc can be cleaned with a cotton tip and alcohol too.

When it's all clean, //slightly// re-bend the fingers to restore their
original contact pressure, put a small amount of switch cleaner / lubricant
on the disc, and reassemble. When refitted to the hifi, you should then have
a working control again. I do probably a couple a month.

Arfa



This was exactly my experience with my high end Pioneer receiver, which
was driving me mad because its sound volume was jumping from normal
level to maximum , almost blowing up the speakers, by just moving the
volume knop slightly.
Simply cleaning all vaseline from the contacts in the rotary encoder
with some alcohol did indeed the job ... I guess all "digital volume
controls" with grease on the shaft will suffer from this sooner or
later... unless they are constructed in a different way, preventing the
leaking of lubricant to the interior.