[Leica] Re: Contact cleaner

[lrzeitlin at optonline.net (Lawrence Zeitlin)]

On Jul 26, 2006, at 10:50 PM, Jim wrote:

> It was on battery contacts in a Radio Shack multimeter that I got in 
> trouble
> with a contact cleaner.  I believe the cleaner was put out under the
> ChannelMaster name.  Perhaps the stuff is not compatible with battery
> contacts.  I had used it on the old rotary TV tuners, before electronic
> tuning came into vogue, and it seemed to work fine.  I then used it as 
> a
> universal cleaner for contact problems.

Channel Master was one of the manufacturers of the old rotary TV 
tuners. I don't know if they actually made the cleaner of the same name 
but I'm sure it met specifications for their tuner contacts. They used 
gold flashing on the rotary contacts and relied on minimum spring 
pressure to make the connection. I guess that's the way you have to do 
it if you are going to change TV channels a dozen or more times a 
night. Most of the multimeters I have had over the past years used wipe 
contacts on the main selector switch. A moving element is wiped between 
a pair of spring loaded contacts every time you change the setting. The 
wiping action cleans the contact after a fashion although you lose a 
miniscule amount of metal each operation. To keep the pressure 
constant, the contacts are usually made of spring steel lightly coated 
with silver or rhodium. Only the most expensive (i.e. > $100 a unit) 
use beryllium copper springs. But then multimeters are not used for 
channel surfing and the switches rarely need cleaning. My latest 
RadioShack digital multimeter only cost me $15 and was made in China. 
Who knows what type of metal they use in their contacts. Probably 
strips of old tin cans.

I assume that Leica uses gold plated contacts for their expensive motor 
drives and other switches, but I don't know for sure. The cost premium 
would only be a dollar or so per camera. I know that Olympus does and 
the unit price is a lot lower than Leica. Alcohol works fine on such 
contacts if you can wipe the surface with a swab without leaving cotton 
fibers behind. Incidentally, does anyone actually know what Leica 
technicians recommend for contact cleaning - or do you have to send the 
camera to Solms.

Larry Z