Repair of remote control contact pads

[Dugie]

Hi,

Some buttons on an original TV remote work, others don't. Looking at the
rubber pad under the buttons, those non-working contacts seem to be worn. If
I complete the contacts on the circuit board with metal, each works fine:
menu, volume, etc.

Is there anything specifically designed for use in re-coating the bottom of
the contacts?

I've bought a Permatex Quick Grid Rear Window Defogger Repair Kit, which is
a "highly conductive" paint-like substance from Canadian Tire. It "Contain:
silver, ethyl acetate, ethanol, 2-ethyoxyethyl acetate."

Thought I'd ask here before opening the $10 product. It may take the wear a
remote gets, or not.

Thanks!
Dugie

 

[Bud--]

Hard to say without looking at it. I have never seen worn contacts - the
usual cause is the "conductive" pad that is pushed down onto the
contacts when a button is pressed. Rubbing the face of that with a very
soft pencil usually works a treat and lasts a fair time before needing
to be repeated.

Conductive paint does what it says on the box. But you may find a soft
pencil works as well, in a very low current situation such as this.

There was a pretty long thread on this on sci.electronics.repair a few
months ago - should be findable with google groups.

bud--

 

[Dugie]

Hard to say without looking at it. I have never seen worn contacts - the
usual cause is the "conductive" pad that is pushed down onto the
contacts when a button is pressed. Rubbing the face of that with a very
soft pencil usually works a treat and lasts a fair time before needing
to be repeated.

Conductive paint does what it says on the box. But you may find a soft
pencil works as well, in a very low current situation such as this.

I did rub the conductive pads with a Q-tip moistened with rubbing alcohol,
which may not have been a good idea.
Your soft pencil idea sounds great, so I'll try the graphite rub.
Thanks for your suggestion, Sue.

- Dugie

 

[Dugie]

the


There was a pretty long thread on this on sci.electronics.repair a few
months ago - should be findable with google groups.

bud--

Thanks bud, I found at least a few threads on Google. Here's one quote;
conductive paint was used, but with results I expected:

"Had a JVC remote, used alcohol to clean the rubber pads and the board.
This worked 5 or 6 times, although remote never worked as well as when
it was new.

"When cleaning stopped working well, bought a bottle of conductive paint
from a local electronics supply house, and re-coated the rubber pads,
cost something like $10. This worked amazingly well at first, like-new
performance. But this stuff apparently is not as durable as the
original conductive coating. 3-4 months and I was having problems with
the remote again."

Sue's graphic idea sounds good.

Dugie

 

[Dugie]

Oops, that should be GRAPHITE. Sorry!

Sue's graphic idea sounds good.

Dugie

 

[Dugie]

the


I did rub the conductive pads with a Q-tip moistened with rubbing alcohol,
which may not have been a good idea.
Your soft pencil idea sounds great, so I'll try the graphite rub.
Thanks for your suggestion, Sue.

- Dugie

I tried an 8B, the softest graphite pencil I could find. To my multimeter,
that graphite is totally conductive, but didn't help. :-(
Have you had success with this method, Sue?

BTW, my mistake re: the "worn contacts." The contacts are of course fine;
the conductive pads are the worn parts.

Dugie

 

[Dugie]

I have never found it *not* to work. Only that it may need repeating
every few months if used "continuously".

Of course, there are many reasons why it might not work, including that
the problem may have been elsewhere all the time - eg the contact tracks
may go to a connector joining them to the main board and there might be
a bad contact there, a pcb track may have a hairline crack, there may be
contamination somewhere, shorting out all or part of the switching
matrix, etc, etc.

The way the switch circuit works is that buttons are wired up in sets -
with one "supply" line feeding, say, 4 buttons, a different line feeding
another 4, etc. If you do have a break or bad connection in one of the
"supply" traces, it will affect *all* the buttons using it but not the
others. If that sounds familiar - it may not be a problem with the
conductive pads but the ciruit traces/ connectors.

I've rubbed the pads gently at first, then used more pressure. The graphite
hasn't worked once; maybe a 9B pencil isn't soft enough. Or it doesn't
adhere.

Using a known good pad from the same remote, and pressing the pad to each
contact in turn, all functions of the remote work. That could indicate the
circuits etc. are ok, but I'm unsure if that's an accurate assumption.

Thank you for the interesting information. I'm learning that a "simple"
remote control is quite a marvel, and quite complex, thus a lot can go
wrong.
It's a challenge now to me, one I'd like to solve, not a necessity, so if
this is frustrating, I'll drop the thread.

Dugie