Part# x2218 is a Key Contact board (circuit board) that has been damaged due to moving in near zero temperatures. 5 keys from C# above middle C to F# tracks back to the circuit board that appears to be damaged and notes won't play. I can't find a replacement board anywhere. We have disassembled the keyboard and traced the trouble to this specific part.
SOURCE: Yamaha electronic piano keying circuit broken
The interdigitated fingers are circuit traces coated with a very hard, non wearing, carbonized type conductive surface. If a board crack runs through this carbonized area, that is FATAL. Replace the circuit board.
Realize that these contacts drive high impedance CMOS circuitry so the contact resistance is often in the 200 to 1000 ohm range.
The silicone rubber domes contain a conductive rubber pills, often two of them. One contacts the fingers before the second and the time difference between those is the measure of "velocity".The silicone dome acts as the restoring force for the key.
The keyboard is scanned as a matrix. Strobe lines intermittently select the first and then the second of the finger patterns, ONE octave at a time. The octave, 12 notes worth, are read in parallel one at a time.
The diodes are "disconnect diodes" which preven sneak paths when more than one note is held that are in different octaves.
Testimonial: "Thanks! But I didn't see any domes in the cones, & didn't measure any conductivity in them or the traces(?) + this unit isn't touch-sensitive."
SOURCE: Digital Piano has sticking key
Typically LOTS of screws... concentrate on those around the edge. USE GREAT care and force nothing when removing the cover...and great care of cables between the cover and the base. Mark the cables so you remember the direction they attach.
When you get edge screws out, then gentle lift and see where it seems to be held...
Some of these synths have 50 to take out to get apart. MOST are in plastic bosses and keep track of the size and length as you can put too long a one in the wrong place and crack the boss.
I use a compartmented plastic tray to keep the screws in order.
SOURCE: Yamaha W 7 keyboard problem I have a Yamaha W 7
under the keyboard there is a switch for each key, try to clean it whit water and a smooth paper.
I have Roland keyboards and it happens after playing a lot.
good notes
Testimonial: "Thanks for the info. I will give this a try and hope that this solves the problem."
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