I’m having a problem with my MOX6, if I slide off Ab to A it keeps the Ab stuck on whilst the A is sounding, it doesn’t release that Ab note and if i move back to Ab quickly from A it doesnt release the A note.  This happens in every octave.  I’ve tried changing the rubber contact strips, this doesnt solve it.

Could it be faulty key contact circuit boards?

Just so we’re using the same terminology…
Yamaha refers to black keys as sharps, not flats, so Ab = G#.

Is the problem evident with D and D# keys as well?

Yes it is happening in D and D# too

Ignore this

Yes it’s happening in D and D# too.

eltmatt - 06 November 2019 01:48 PM

Yes it’s happening in D and D# too.

Those keys use a pair of the same key matrix lines as G# and A. I suggest checking the 12-conductor cable that runs from the keyboard to the KEY-IF (key interface) board for a bad connection. If you live in an area with high humidity, check for corrosion at the cable connectors and on the board.

Ah thanks! I was looking at those earlier, do you know which cable it is, there appears to be three, 2 larger ones and a smaller one.

Is there a way to get rid of the corrosion or will I need a new cable or board?

eltmatt - 06 November 2019 06:41 PM

Ah thanks! I was looking at those earlier, do you know which cable it is, there appears to be three, 2 larger ones and a smaller one.

There are indeed three cables going to the KEY-IF board (which is located between the JK and DM boards, and is relatively small) - having 5, 7 and 12 conductors. The cable I’m referring to is the 12-conductor one from CN1 on the 61H (high, C4~C6) contact board to KEY-IF CN704. It is not the one going between the 61H and 61L (low, C1~B3) contact boards.

 

eltmatt -

Is there a way to get rid of the corrosion or will I need a new cable or board?

In many cases removing and reinstalling the cable is enough to reestablish proper contact if there’s some light corrosion. Sometimes just wiggling the cable a bit is sufficient. If you’re not familiar with working on flat cables, you might want to have an experienced technician look at it, since damage to a connector can require board replacement.

The need for board replacement due to corrosion would depend on the degree of any found. Your member profile doesn’t indicate your location. Are you in an area of high humidity, especially where there’s “salt air”?

I live in England, my MOX is usually stored outside in a van most of the time when it’s cold and then brought inside so the humidity could be due to moving it from cold to warm quite a bit.

I check the boards and connections under the keys and found no corrosion so I guess I will check the Key If board and end of the the cables.

Thanks a lot for your help!

I’ve opened it up and inspected both boards, I’ve had the cable out at both ends and put it back in, the problem is still there and I can’t seem to see any visable corrosion so I’m not sure what to do next or which part to replace first.

I’ve attached some pics incase theres something I’ve missed!

Thanks again.

Click thumbnail to see full-size image

eltmatt - 07 November 2019 01:06 PM

I’ve opened it up and inspected both boards, I’ve had the cable out at both ends and put it back in, the problem is still there and I can’t seem to see any visable corrosion so I’m not sure what to do next or which part to replace first.

I’ve attached some pics incase theres something I’ve missed!

Thanks again.

The first picture appears to show some dirt in the vicinity of CN1 (61H board), and flux residue from soldering at that connector’s pins. As a fist step, I suggest that the area be cleaned and the flux removed - certain types of flux can become conductive and/or corrosive when there’s sufficient moisture present. Sorry, but I won’t go into cleaning details, since I don’t know your abilities or those of any other Motifator members who might read this thread. There are online articles that describe flux removal, but anyone attempting their own repairs is doing so at their own risk.

Cleaning might not resolve the problem. There may be a circuit failure on the KEY-IF board, or some other problem that isn’t evident from your description or pictures. The unskilled or inexperienced should leave the work to qualified technicians.

Best of luck with this issue.