Although this topic has been discussed in scattered posts, I thought I would summarize my recent experience with replacing
the contact strips in my Nord Piano 4. Hopefully, lessons learned will help those who want to attempt a repair.
Background: Nord Piano 4, 5-1/2 years old, home use only, 30 minutes to an hour daily.
Symptom: Notes dropping out when hit repeatedly, mainly in middle register.
I was a little annoyed that problems occurred at a young age, but then again, years ago I had an old Korg digital piano with
a Fatar keyboard and that needed work after a similar time. I bought enough contact strips for all 88 keys from Syntaur with
a total cost of about $100 USD.
Taking the Piano 4 apart was relatively straightforward. First, remove the two screws in the bottom that hold brackets
securing the top cover. Remove the side panel screws and the screws along the top rear. Carefully lift away the top
cover until you can reach in and unclip the ribbon cable from the processor board to the display/control board and then
set the top cover aside.
There are three cables from the processor board to the keyboard assembly. This is where it gets difficult. Gently rock
the cables out of the connectors. The two large ones simply pull out. The little one, going to the calibration board
attached to the keyboard, pulls out upwards, but has plastic retainers. I was unable to get this cable out without breaking
the retainers off. Not to worry, the connector is a tight fit and the lack of retainers will not be a problem.
As some YouTube videos suggest, one needs to remove the processor board because it sits partially over the keyboard assembly.
This is NOT necessary (on the Piano 4), leave the processor board alone. Remove all the keyboard securing screws from the bottom of the unit
and then the screws from the top. Gently pull out the entire keyboard assembly away from under the processor board, being careful to
grab it from the ends on the metal parts. Turn the keyboard upside down and put it on something like a blanket to cushion it a bit.
Removing the contact strip boards is not difficult. First remove the nine metal support brackets (3 screws each). Unplug one
end of the ribbon cables between the boards using the same care you did with the ones on the processor board. Mark the
boards with a pencil so you don't forget the orientation. Unscrew all the boards and lift out. If the keyboard mechanism
has a lot of dirt, vacuum it out at this point. Wipe away any grease that might have migrated to places where it shouldn't have.
The little calibration board can be unscrewed and set aside also.
The contact strips pull away easily. In my unit, the underlying carbon pads on the board were pristine, but I took a clean
lint free cloth, dampened it with 90% isopropyl alcohol, and gently wiped the contacts. Use as little moisture and pressure
as necessary.
Installing the new contact strips is not difficult, just tedious. The larger pegs go in the holes pretty easily. The smaller
pegs will require you to poke them with something like the end of an unfolded paper clip. Make sure that the strips are
completely pushed down the whole way. You should be able to hold the board and look down the entire set of contacts and
they should be completely in line. Don't get frustrated and stop before you are sure that they are perfectly set. It took
me about one hour to do this step to my satisfaction.
Reassembly is straightforward, but try to torque the board mounting screws evenly. The hardest part is pushing the ribbon
cables back in. There is probably some tool (90 degree pliers?) that would make this easier, but just be careful and don't
force things.
Aftermath: It took 3 hours to do this repair. When everything was put back together, all 87 keys worked fine!!! Wait a
minute, aren't there 88 keys on a digital piano? That's right, one key was malfunctioning (no sound). So I took it all
apart again and it turned out that one of the new contact strips had a carbon pad that was glazed over. Syntaur made good
and immediately sent me a new one. Now everything works fine. Moral: examine the new strips carefully before installing them.
Analysis: A post-mortem analysis of the old contact strips revealed the following. The carbon pads both on the strips and
the underlying board were, for the most part, in good shape as far as I could tell with an ohmmeter. What happened was
that the rubber posts under the carbon pads in the strips started to break at the bottom. A careful examination showed that 31 of the 88 contacts
had started to separate - all of them on the longest of the triple posts (looking from the bottom).
When these Fatar keyboards start misbehaving, the usual recommendation is to clean things. Although that might help, it
doesn't address the problem where the posts inside the contact strips start to tear away. And that was the problem with mine.