Broken Remote for Cable Box

Aug 05, 2008 5 Replies
N

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?


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J

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.

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....

jak

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L

also check the oscillator by tuning an AM radio on the low end of the band...say 500 KCS and push any button on the remote...you should hear a buzz

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N

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

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

.
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N

I should have explained better in the original post: only the row of 3 keys stopped working, the other 30 (or so) are all OK.

.
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J

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

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