Michael A. Terrell wrote in message
...

N_Cook wrote:

Michael A. Terrell wrote in message
...

N_Cook wrote:

Why do they not use "dry lubricant" perhaps
locksmith's graphite as long as in a minute quantity.


The grease is needed to prevent metal migration across the open
areas
as they slide. I've seen people try to run similar items dry, or with
other crappy lubricants. Graphite would need something to hold it to
the board, and you would need enough that would cause leakage as the
sliding contact compacted it to the surface. Good old fashioned 'GC
Tunerlube' does an excellent job on sliding contacts.


--
You can't have a sense of humor, if you have no sense.

I can see that with multifunction DVM rotary dials where there is small
gaps
between tracks. But the 2 rotary encoders I looked into this week were
about
1mm wide spokes tracks with the contacts at the periphery so spaces of
about
5mm of insulator disc material


Not 'between tracks', but between the pads a moving contact uses. 25
years ago I serviced CATV converters for a living. I had to use a soft
eraser to remove the tracking between contacts if the original lube had
hardened, or where an outside service company had wiped away the old
grease and used a fiberglass brush in a half assed attempt to clear away
the smear of silver. I did well over 1000 repairs in four years with a
return rate of a little over .2%. Over 50% of the units returned from
the outside service company were either bad, out of the box or failed
within a month. I was hired to create the in house service department
because we had over 1/3 of our converters either at the outside company,
or on a UPS truck and in transit. We added 350 new customers without
buying any new equipment, after I had the in house repair facility set
up. We went from the worst rated CATV company in the reigion to the
top, in under six months.


--
You can't have a sense of humor, if you have no sense.

What was the spacing between pads on those CATV units? The pads or tacks in
these switches were about 5mm. As far as I can tell the problem was not
metalisation smear over the insulated gaps but a problem while in pad
contact. No visible smearing of metalisation seen on either switch. These
pads are just like spokes of a wheel and once the problem started it is much
the same around the whole disc, not specific to one or two positions