I have seen this issue when playing a chord from bottom up F G# A# and C when these notes are played as a chord a loud B tone sounds (instead of the C on top)…Happens in all octaves. It also happens on other notes in chords. It is almost like the chord\note sequence creates a short… I have updated firmware and also powered on with top key pressed to reset the keyboard. I see a replacement board on Syntaur but not sure if that is the fix for this…There are lots of similar posts w Reface series showing this problem. This problem does happen when controlling a module w this keyboard…any ideas outside of calling Yamaha? Thanks!
Sounds like an issue with the MK board. Probably corrosion. Order the board and rubbers
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Thanks sounds like a plan…
I have replaced the key trigger board, same issue as before same notes retrigger in different octaves
Rubber key buttons look fine…may be somewhere in the main board
Like an overload of a buffer that handles midi…also sends the same trigger loud note out always a B note that sounds while playing the on a 5 note f minor scale (keeping the prior notes held down like a chord
Also happens while playing (keeping previous notes held) C C# D# E F
Once I get to the F note a loud F# sounds out
I can say for sure but sounds like the triggered sound is at 127 or full velocity…
Just keeping this updated in case someone else runs into this issue…
I found a bad diode on A#2 (left side) may have caused the weird B triggering
Also found F#3 3rd diode but may be shorted because pressing the multimeter leads a little harder gave resistance. Now to find those little surface mount diodes…
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I’m not convinced of the diode issue other than maybe solder short because I’m getting readings on all of the diodes …so as PCM tech mentioned i will swap or replace key rubber contacts …I didn’t realize one faulty set can affect every octave ghost note issue…real techs understand that already…I’m an amateur and a bit hard headed at times, but I needed to understand why and how this can happen on the scan matrix …I’ll post results in the hope that it can possibly help others with limited knowledge such as myself
This will help to understand how the key scanning works:
Keys are scanned in groups of 6 in this case - some key scanners scan in groups of 8.
If looking at the bottom yellow part you can see that anything faulty with that one line will affect a group of 6 keys - but no others.
If looking at the top part you can see that anything faulty with one line, in this case let’s assume a break at the red line. will affect every 6th key after the break.
This is a very simple keyboard - some larger ones have two or even three key scanning board with the connections to the scanner being some place in the center. Then the fault can be either side of where the signal enters the board (usually the middle board) but essentially the same issue.
The volume of the key is given by the speed at which the scanner sees the contacts closing from 1st to 2nd contact on each key - some boards have three contacts per key.
This is helpful thanks!!!
The weird thing is that the Keybed pcb replacement part has the exact same behavior…a loud B note triggered on all octaves when playing the key sequence (regardless of order pressed and held) the loud B ghost note appears…
Waiting on a new set of rubber key contacts from syntaur …then I’ll go from there…
If it still happens after that may be a bad run of key beds but I’ll have to install new key contacts before any other actions