On Tue, 05 Sep 2006 01:18:20 GMT, Jumpster Jiver
wrote:

an_Musicant wrote:
: My 5 year old Sony MHCMG110 mini stereo has a problem:
:
: The volume knob control doesn't always work properly. Before I open it
: up I thought I'd post here and get some guidance.
:
: The volume level heard appears to correspond correctly with the digital
: level displayed, which goes from 1 to 30, maybe higher. I never have it
: higher than around 20. However, when spinning the volume knob those
: numbers don't always advance or decline as expected. Sometimes they even
: go backwards briefly!! When using the remote control, the volume changes
: smoothly and properly.
:
: My first thought was a slipping pulley, but how would that make the
: volume go the wrong way? It doesn't go the wrong way a lot and not much
: - generally one digit and only momentarily when spinning the dial. Maybe
: it IS a spinning pulley. Anyway, this thing is pretty big and complex
: what with all the features (and I'm therefore hesitant to open it):
:
: 60 CD changer
: 2 cassette bays, one recording auto-reverse
: AM and FM
:
: The speakers are separate (this is the stereo version, not 5.1 or 4.0)
:
: I bought the service manual yesterday online (they emailed it to me) and
: I printed it out. It's mostly full of the schematics, but there are
: parts diagrams and 3D assembly/disassembly diagrams. Looking through the
: whole thing I didn't spot anything that would directly relate to this
: problem. I figure I can either live with it or open it up and try to
: find the problem, maybe replacing a pulley or applying a rubber
: rejuvenator (recommendations?). Or, I could get a learning remote and
: use IT to change the volume (the one that came with the Sony has a kind
: of weak signal). I'd rather fix the spinning control than have to use a
: remote. Thanks for any guidance/help.
:
: Dan
:
:That type of volume control uses LEDs and light sensors to detect
:movement of a flat wheel with little holes in it. Either the holes have
:become clogged with dust or the LEDs have gotten weak or coated with dust.
:If you disassemble the control to clean it you may never get it back
:together correctly or may cause it to stop working completely, so your
:best bet is to use the remote control for volume adjustments.
Ah, that's one reason I posted. This thing is big and seems
complicated. I've opened a lot of stuff but nothing this complex. I do
have the service manual, but will think at LEAST twice before I start
taking it apart.

Thanks so much for your description of the mechanisms at work here. If I
go in there, I'll have an idea what to look for. Being in my kitchen
where I cook, there's dust and grease coated dust particles floating
around quite often. I occasionally clean off the unit of all the grease
that accummulates on the surface. Some of that has probably found its
way inside.

Dan