Fixing TV remote control

Today we fixed one of our TV remotes. The play button wasn't working when pressed (all other buttons worked fine, so we knew the batteries were ok). I thought it was either dirty button contacts or something electrical had come undone and needed to be connected back together. It worked again when we opened it up and cleaned the inside with rubbing alcohol, so it must have been dirty or dusty.

If you've ever opened up a simple calculator with rubber buttons, you can see how the buttons are part of one large rubber mold that presses on a circuit board underneath. The underside of the mold has black contacts that touch related contacts on the board when pressed. This bridges an electrical connection on the board and acts like a push-button switch. Our remote used the same concept. If the contacts are dirty, then the connection won't be strong and possibly won't work.

One interesting thing I noticed was "fixibility" of the remote. On one hand, it was very hard to pry open since there were no screws -- it snapped together. On the other hand, the circuit board was helpfully labeled on the inside, a strong hacker-friendly feature. My next post will be about why this is valued in the "maker" and "hacker" community.

Top cover removed

Rubber button mold

 Black button contacts

 

Circuit board top

Closeup of circuit board top. Notice contacts and helpful labels.

 Circuit board bottom. Notice the infrared light on left, which sends the signals to the TV.