"Graham" wrote in message ...

"Sylvain VAN DER WALDE" wrote in message
...
Hello all.

At the present time I'm not trying to get it from the distributor,
although I may not have any choice.
Now, we're not dealing with the usual volume control (potentiometer)
which has 3 terminals (one connected to a wiper, and the others connected
to each end of a resistive track).
No, this damn "little critter" has 7 terminals and 2 mounting lugs
(printed circuit mounting).
It has a blue body measuring 16x15x5 millimetres.
Looking inside: the metal wiper assembly is attached to the plastic
spindle, and has 2 separate sections (one with 3 wipers, and the other
with 2).
It looks as if there are 3 or 4 resistive tracks (it's difficult to be
precise without spending more time to observe them).
Has anyone seen or heard of such a volume control? Is it a proprietory
(I'm not sure of the spelling) or a standard part?
It's completely sealed, so I couldn't use my switch cleaner (which has
always worked for me).
Anyway, I've had to snip though the terminals and mounting lugs, as it's
the best way to deal with a "plated through" PCB.
Can anyone understand/explain the design theory behind this item, and/or
suggest source/s of supply?
P.S. I believe that the receiver is designed in the UK, but it's made in
China.
P.P.S. If it had been any other fault, I would have sent the radio to
Pure for repair (if such a repair was deemed economical). I have many
radio receivers.

Thanks in advance.

Sylvain.

It sounds to me that the "resistive tracks" are in fact on/off contacts
and
the device is in fact an "encoder disk"
The microprocessor looks at the state of the switches in real time and
can determine the direction and speed you are turning the knob and
adjust the volume accordingly.

Usually there is no need for a mechanical stop, as on a pot.

Actually, there are stops on this one. If there had not been any, then I
would have known that this component was (as you describe above) an "encoder
disk".
Nevertheless, I believe that you may still be correct in your assumption.

Does that make sense?

Ha! Yes! I think that we may be getting somewhere. I know only a little
about such things, but enough to believe that you are on the right track (I
believe that my communications receiver has a _rotary frequency control_
that works on that principle, and has no stops).
Let me tell you why I wanted this "volume control" changed: On that radio,
the volume goes up _immediately and rapidly_
as you rotate the knob. The fault is, that at the _very start_ of rotation
the volume control works intermittently, making it difficult to get an
acceptably low but adequate sound output (at night time). At the usual
daytime sound levels, the volume control works OK.
If you have any further remarks about this, I will be pleased to hear them.

Sylvain.

--

Graham.

%Profound_observation%