RE: [CAD_CAM_EDM_DRO] Question on connector used on servos

It is fairly common knowledge in the PC world that when buying DIMM or SIMM
memory modules, you should get the ones with the plating that matches that
on your motherboard sockets. Supposedly, the dissimilar metals will have a
reaction that causes inferior electrical connections.

Andy Wander
Verrex Corporation


-----Original Message-----
From: Jon Elson [mailto:elson@...]
Sent: Tuesday, April 06, 2004 10:48 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Question on connector used on servos



JanRwl@... wrote:

>In a message dated 4/5/2004 11:52:45 PM Central Standard Time,
>mgamber@... writes:
>The brushes have .187 quick connects. OK to use or is soldering

necessary?<<

>Not if you use fresh connectors, with adequate "spring" so that they have

to

>be PUSHED-on with some degree of force. (That is, if they just "slip on"

with

>ease, they are not sufficiently tight).
>Also the encoder has .100 spacing pins that appear to be gold plated. Do

you

>recommend getting gold plated connectors to mate with them? I know that
>encoder wiring should be as fail-safe as possible, but will gold plating

buy me

>anything here?<<
>Yes, actually. Gold virtually refuses to corrode with all but man-made
>corrosive liquids. However, if you put a TIN-plated jack on a gold-plated

pin,

>metallurgical reactions (metal-flow) will take place, and there will be

soon

>layers of strange Stannous-auric alloys between the pin-surfaces, and

T'Paul is

>still trying to quantify the deleterious effects upon signal integrity of

that

>substance.
>
>High-quality sockets, pins, jacks, and such are NOT gold plated to make 'em

>purty, but for a
>REASON! And it DOES make a difference! It'd probably be better to put
>mating TIN-plated parts together than to mix gold and tin, but I have not
>personally researched that with 20-year trials. Anyone know?

>
>

My experience, over 30 years in the electronics/computer business, is
that tin-plated
connectors have a life of about 10 years after the factory sealed
package is opened
to the air. In bad environments, it is less. The contacts eventually
corrode down
to the contact area, even though that is supposed to be a "gas tight
bond". If the
connector pin is carrying a few amps, it will often get real hot and
maybe even melt
the plastic part of the connector. I have had LOTS of older gear that
had bad
connections in these AMP mate-n-lok and Molex type connectors.

I doubt mixed gold and tin connectors are any worse than plain tin.

Jon



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