On Sat, 8 Jan 2011 11:49:26 -0800 (PST), Thomas Williams
wrote:
For remote controls that have been properly cleaned out and still
don't work like new, I understand some conductive material needs to be
coated onto the circuit board contacts on the inside of the pad
buttons. Reviewing web discussions of this I wonder if a good approach
may be to mix graphite in silicone glue and lightly coat the surface
of the pad's underside. Anyone tried this or have a thought on it?
Others have used electrically conductive paint (e.g., that purchased
at auto supply stores to reconduct broken rear window defrost
circuits) but that would not seem to be as flexible as silicone glue
with conductive material mixed in it. I did read where someone mixed
finely shredded copper (from pipe) with thinly diluted white glue and
it worked well (but for how long?). It would seem that the latter
approach would be better if silicone glue was used, as it is more
flexible. What ye think?
I use conductive paste:
http://www.hifi-remote.com/manuals/p8/rs-rf.shtml?15-1995#wornout
http://www.permatex.com/products/automotive/specialized_maintenance_repair/auto_glass_lens_repair/Permatex_Quick_Grid_Rear_Window_Defogger_Repair_Ki t.htm
If available, I've also used Aquadag (water based graphite paste).
http://en.wikipedia.org/wiki/Aquadag
Before you attack, clean both the graphite button bottom and the gold
contacts on the PCB with alcohol. It might just be grease on the
contacts.
The problem with mixing your own conductive graphite concoction is
that only a few formulations are actually conductive. If you don't
add enough graphite, or the graphite particles are too small, they
will not touch each other and therefore will not be conductive. I've
tried to make my own conductive glue with powdered aluminum and epoxy.
It failed badly and was mostly an insulator. I eventually got it to
conduct by radically adjusting the aluminum to epoxy ratio, but with
little epoxy to act as a binder, it was terminally brittle.
Anyway, try it. You might get lucky and find the right combination of
grain size and graphite to glue ratio. Test with an ohms guesser.
Your remote should work with anything less than about 1,000 ohms per
square, but I'm guessing:
http://en.wikipedia.org/wiki/Sheet_resistance
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558