How do I fix a key that wont play on my Roland D-20

Yes, you can use the second pedal on a Roland BK-5 keyboard to transpose the key of the music that you are playing up or down by a semitone at a time. To do this, you will need to press and hold the second pedal while playing the keyboard. You can also use the transpose function in the settings menu of the BK-5 to adjust the key of the music that you are playing by a specific number of semitones.

i moved you from computers
to music + roland.
it needs service, find a shop to fix it;
IT RAN FOR 1995 TO NOW, 26YEARS
FRANKLY AN AMAZING RUN. FOR SURE.
it needs service, you have 2 choices besides upgrade.
1: shop fix it.
2: buy the service manual and learn electronics.
check DC power rails inside first and fuses .

It's most likely the keyboard contact strip needs cleaning or replacing.

DUST on sensors! If you have steady hand, you can remove the entire keyboard. Using a computer vacuum cleaner, clean the sensors on the instrument, then replace the keyboard carefully. Or, take it to a technician to have the keyboard sensors cleaned.

have a look here:
http://www.ehow.com/how_8698510_fix-roland-cube.html

although it doesn't mention the fuse you will probably find it. Sometimes there is a fuse access on the outer case.

Sorry, but Roland uses the opposite sense switch. They use normally closed where Casio requires normally open contacts. SOMETIMES one can rewire the pedal internally, but you have to be mechanically and electrically inclined to do that.

There is a rubber "bubble contact" strip under the keys, and pressing on a key pushes the bubble down, which makes contact with the circuit board underneath. Any foreign matter that gets in the way of this contact will render that note unplayable, and that is likely what has happened. You can remove the keybed, remove these strips, and clean the board with rubbing alcohol. Don't use alcohol on the bubble strips, as it is not good for the rubber.

Sometimes, you can simply tape a small piece of cardboard, like from a cereal box, onto the bottom of the key where it pushed on the bubble, and this can fix the problem.

The bottom line is that you will have to remove the keybed, and that may be a daunting procedure unless you're used to that kind of work. So you may want to just take it to a service center. You can get parts at www.syntaur.com. Good luck!

The key contacts need to be cleaned. They are usually conductive rubber pills in silicone domes that get pressed onto circuitboard traces by the keys. Disassemble to get at the contacts. clean ONLY with 99% isoprophyl alocohol and Q tips. Clean both the pills AND the circuit traces they contact.

Be very careful of cables when opening the unit. Document where all the screws go and their length and threads.

Roland FP is a nice keyboard but has a known problem on cracking key weights. There is a counter weight under each key to push the key upward. There are two sizes of weight beams, longer one for white keys and shorter one for black keys. Roland did not make the original weight beams strong enough to last. They will crack and eventually break. When it happens, the key will stay down. Fortunately, they can be easily replaced.

Roland FP-8 has 4 black screws at the bottom on each side end. Remove the screws, flip the ends up and expose the interior. Near the hinge of the problematic key, carefully ply open the hinge tabs and remove the key from the hinge. You will find a weight beam under the key. Remove and inspect the weight. There should be a metal wrapped in a plastic beam. If the metal part is missing, find the missing part and replace with a new beam. You can order weight beams from Roland. It costs about $10 each plus shipping. Put everything back in the reversed order.