Korg Forums

[jasperdog]

I have 3 notes with defective velocity sensing on my Krome 88 (all C#'s and F#'s, but none in the same octave) so I bought 4 replacement rubber contact strips. Can anyone give detailed instructions for disassembly and strip replacement? By removing all the screws from the bottom and disconnecting a single ribbon cable, I managed to separate the bottom keyboard half from the top control/interface section.

There appears to be 11 screws holding the entire keybed assembly to the bottom of the outer keyboard shell, and there are 3 screws that attach each octave of keys to something underneath. At this point I'm a bit fearful of taking anything else apart without directions.

So please help me out

[jasperdog]

Well, no one helped me out, so I'm posting my own reply to help others who might need to replace some of the rubber contact strips to fix Krome velocity problems. Replacing the rubber strips that corresponded to the offending notes solved the velocity problem 100%, but there's some lessons learned here as well.

The first step is to turn the keyboard upside down on a table with some books at the edges/center to eliminate any pressure on the joystick or knobs. This requires removing ALL the gazillion screws on the back panel, some of which are in deep wells and along the very back edge. Although I tried to mark all screws with their location, writing with a permanent marker on food storage bags, my descriptions were too crypic and I wound up with 8+2 leftover screws when I completed reassembly, so BEWARE. A better method would be to write 1, 2, 3, 4 etc. ON the back and internal panels as each type of screw is removed, with bags for each screw type (about 6). Who cares if the bottom and internals of your synth is defaced with some scribbles!'\

After all the bottom panel screws are removed, you can separate the top and back panel assembly, along with most of the electronics, from the bottom shell section, but ONLY after unplugging a single row ribbon cable interconnection. There's about 10" of excess cable between the two sections. Make a note that the white wire end plugs in closest to the screw.

You are now at the point I was in my first post in this thread. You will now remove the keyboard assembly from the bottom shell assembly by removing the 11 screws. Make note of which one secures the ribbon cable and which one has a grounding lug. Remove the keyboard, you will work on that.

The keyboard has octave sections secured by 3 screws with a couple extra for the top note and lowest notes. I had velocity problems with F#1 C#3 and C#5, which would always sound at max intensity. (I consider the lowest note to be A0 and C1 is the lowest C.) Each 12 note rubber strip starts at C# and ends at C, and there's a special shorter strip for the lowest 4 notes. So I had to replace the 1st, 3rd and 5th strips with new ones from guitar-parts.com, but to be safe I also replaced strip #2 and I swapped strip #4 with the top octave.

To replace a strip you have to remove all the screws and then each set of keys by prying the clips at the top with a small straight screwdriver. The strips pull right out of the circuit board easily. When inserting the replacement strips into the circuit board, I used the end of a match to push each nipple into the board and then a toothpick to make sure it's all the way in. If inserted properly, you should be able to put a small amount of sideways pressure on each contact without the nipples coming out of the board.

If you're satisfied that the rubber contact strips are all seated properly in the circuit board, it's time to reattach the keys, starting from the left. To do this you need to support each octave from underneath then place the front of the keys into position before the back end of the keys. I used a piece of corrugated cardboard cut 3/8" wide and a little longer than the width of each set of keys. Once the keys are in position, you can pull out the cardboard then snap the back of the octave into place. Be careful not to disturb your contact rubbers when you pull out the cardboard. Note, if you don't support the keys from underneath when placing them, the black keys won't work.

Reassembly is basically the reverse of disassembly, but you will need some care when reconnecting the ribbon cable and take care again to protect the joystick and knobs when you flip the entire thing onto its top again.

PS, not sure I could find the contact strips at guitar-parts.com, at least it didn't seem to list the KROME for keyboard contacts.