This short Instructable covers how I fixed the contact buttons on my Harmony 650. The remote itself uses 2 types of buttons: the metallic dome ones, and rubber contact ones. They both fundamentally work the same: when you press the button, a switch is closed on a circuit, telling the processor to send a specific code via IR to the device its pointed at. The metal buttons do this by touching a metal dome across a contact pad. They will continue to work as long as the dome can spring back into shape. The contact buttons rely on a conductive surface on the bottom of the rubber button to do the same. Unfortunately some of these remotes use a conductive material that wears out rather quick. Fear not, its easy to make them conductive again!
Step 1: Whats Needed?
All thats needed is a set of micro screwdrivers and a soft lead pencil
(a #2/HB, B or softer). Just like the old ScanTron tests, we will be filling in the circles. Conductive paint works better if you can get some, as does metal foil tape.
Step 2: Take It Apart
There are 6 screws and 6 clips holding the two halves of the remote together. 4 Screws in the battery compartment, and 2 under a stick-on cover near the transmitting end. Remove all 6 screws and put in a safe place (they are small!).
There are 3 clips on each side of the remote. Starting at the thin end, slip a pry-tool (or small flat-head screwdriver) into the seam and pry the lower (black) half out and down. Work your way to the thick end. Once all 6 are released, lift the top straight up and off (the battery contacts must slide out of the top half). Slide the IR window down before lifting it, the clips at the top end of the remote hold it in place. The screw holes should be large enough to let you slide it down far enough to release.
Step 3: Remove the Main Board and Expose the Buttons and Start Coloring
There are 3 screws holding the main board in place, remove them. This will expose a transparent/white plastic piece that should lift off easily to expose the button membranes.
Using the pencil, color in each black dot! Go over them heavily to make sure the pencil lead really coats the dot. They should end up with a shiny gray color instead of the black they were. For a more permanent solution that works much better, use conductive paint to coat the black dots instead. Don't use too much paint though, a thin coating of it is plenty. Too much and it will flake off and cause problems like ghost presses and lockups. Another option some commenters have mentioned is using foil tape: cut small pieces of metal foil or foil tape and affix to the buttons. Its more work but won't flake off as easy as the paint or wear out like the pencil solution tends to do.
Leave the other posts as they are, they are either guides for holding things in place or presses for the metal buttons that don't need this fix.
Step 4: Close'r Up, We Are Done!
Once all the dots are shiny gray, put it all back together again. It should work like new!