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jakdedert

lid wrote:
jakdedert wrote:
lid wrote:
I've a broken remote for a cable TV box. It's been replaced,
so the repair is non-critical -- just-for-fun!

Anyway, 3-buttons failed simultaneously. They are horizontally
adjacent.

After disassembling and inspecting -- there seem to be no
broken PCB traces and the PCB contact portion of the keyboard
looks OK.

The key contacts are a thickish, black material applied to a
single-sided PCB in an open matrix pattern.

After some simple tests, verifying the "rubber" buttons for the
failed keys work at other PCB pads and that the "bad" PCB pads
weren't activated by "good" rubber buttons, there seem to be 2
possible (likely) failures:

1. A key-matrix leg of the control electronics has "died".
2. The "paint-trace" contact material has disconnected from
its PCB trace.

If the chip's died or a surface-mount element's fried, it's
probably not fixable. (Not by me anyway.)

So -- any suggestions on methods to re-attach the 3-key leg?

Or -- any other failure scenarios?

As a first step, try cleaning the affected pads. That may produce a
fix. If not, short the pads with sharp probes to see if those functions
work. Otherwise, trace back from the keypads, and short the traces
which seem to correspond to them...further back down the line.

I did dry-wipe them with cotten. They look good -- no dust or gunk.

If none of the above produces a response, you might have a component
problem.

BTW, a digital camera makes a good IR detector. Just point it at the
remote when in operation. The IR LED will be plainly visible....

I should have been clearer -- the other 20-30 keys all work. Only the
row of 3 doesn't work.

.
No, I got that. Perhaps your remote has visible LED to indicate button
pushes, but many don't. I suggested it as a visual confirmation of
control input.

jak