On Thu, 5 Apr 2018 17:15:07 -0700 (PDT), Terry Schwartz
wrote:
No Jeff, that's nonsense. Copper tape or aluminum foil tape
will not hold up to the pogo pins rubbing on them. It'll
last a few rotations before it wears thru, or folds up
the tape, or pushes it off the substrate, likely creating
another short.
I'll admit that I haven't tried it with a similar device, but it
worked well enough on an HP8640B signal generator switch that was
somehow mangled. I don't have a photo of the repair, but this is the
switch type:
http://www.learnbydestroying.com/jeffl/pics/HP8640B/slides/HP8640B-01.html
I used 3 mil copper shielding tape without soldering. Something like
this:
https://www.adafruit.com/product/1128
The contacts are made from beryllium spring stock and do not apply
much pressure. There was a slight groove in the copper tape, but no
rips or tears. As far as I know, the generator is still functioning
about 10 years after the repair.
However, you might be right. The signal generator switch has much
less pressure, movement, and use than the robot head. However,
there's nothing lost (except time) in attempting to repair the
original with copper foil or tape. If the heads on the pogo pins are
wide and rounded enough, such a repair might hold together long enough
for the PCB to be cloned and replaced.
I do like the slip ring idea if there is room and a way to secure it.
Agreed. Seems like a better idea than to patch together the existing
slip ring assembly. It might fit better if the it more closely
resembled the original:
https://www.google.com/search?tbm=isch&q=slip+ring+rotary+pancake
Maybe something like this one:
http://www.directindustry.com/prod/bgb-innovation/product-112951-1112523.html
Otherwise, get the original gerbers, or recreate the gerbers in
a PCB cad program, Eagle would do this easily. Then consult with a
domestic PCB house on how to specify the copper thickness and hard
gold plating. Doing it by design rather than some photocopy process
would insure correct alignment with the pogo pins.
Or, go back to the dark ages and make a "tape up" of the board on
mylar film, probably using a drafting pen and India ink. When done,
photograph and reduce the photos to film which would be sent to the
PCB fab house. I'm not sure they know how to handle such dark ages
technology, but it's worth a try.
Nostalgia:
http://www.learnbydestroying.com/jeffl/PCB-Layout/
A "dry" connection does not imply no DC, by the way, it implies
very low current.
Sigh. I stand corrected:
https://en.wikipedia.org/wiki/Wetting_current
However, on a slip ring device, the contact spring pressure is
sufficient to break through any oxidation. Therefore, there's no need
to rely on DC current to break through it.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558