ziozeus wrote:Dear all, after a while almost all notes in the center zone was showing peak velocities issues. One or two were different in that they had some kind of sensitivity, but almost played values from 100 to 127. I've had some problems with warranty pick up and fearing even worse problems I decided to open the keyboard myself to investigate on rubber contacts. First of all I can confirm that the keyboard is nothing more than a kawai RH3 without let off and counterweights. The pcb underneath the keys is a kawai RH88B-KKB-044. The spare part KAWAI is selling as a whole (pcb+rubbers) has blue rubbers from what I can see in the internet, while those in my grand are grey, which I thought were from the previous model (KKB-040). Also to my surprise after researching (extendently!) I have found both are sold separately as 12 key contacts strip! I ordered two strips (grey) just in case, for the future.
So what I did was following the disassembly instructions to be found here in the forum (you will have to disconnect the action connection to the mainboard, easy task not mentioned there) and two very good youtube videos showing details about an mp7 and/or similar contacts cleaning operation. I delicately cleaned the bcp with rubbing alcohol and the rubber contacts with a pencil eraser. Reassembled. Nothing changed. Reopened. Swapped the two center zone rubbers with other two (so I swapped 24 keys with other 24) and cleaned more energically (still not much fearing damage!) both the contacts and the rubber contacts with the pencil eraser. It became black with cleaning (removing maybe some carbon dust laying there from use consumption I guess? And maybe responsible for some false contacts?).
Now everything is fine and I can happily close this nightmare.
My guess is the problem is not dirt (my contacts were all but dirty and my nord is one year old) but maybe 1) eccessive carbon debries for the fact that both the pcb and the rubber strips black carbon parts are new and 2) the fact that they combine together shaping each other with use, so I thing that more than cleaning, the most effective way to solve problems is swapping them.
Also, since some are having problems and others don't, I think that it's a matter of bad luck!
I hope this my experience can help here.
Bye all
Hy guys,
I'm a new user here in the forum. Thanks to ziozues I decided to open my Nord Grand. I confirm that I fixed the peak velocity problem cleaning the pcb, and cleaning and swapping the black carbon rubber strips.
I had some problems with following keys: C4, C#4, D. I swapped the middle strips with the high notes keys on the right.
I post some photos to give you feedback on the disassembly of the piano keyboard, pcb and the rubber sensor strips.
To clean the pcb I used a liquid spray for electrical contacts - I rubbed the pcb with a cotton cloth -, for black carbon I used a simple pencil eraser.
To open the front panel, leave the screw in the rear bottom corner loose. The screw works as a hinge on the wooden sides
Use T20 Torx for the side and rear panel screws.
I hope my post can be helpful.
Bye All.
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