Roland A-800 Pro dead keys

All of a sudden, 8 keys highest E thru B quit working, all at the same time, without hesitation just went dead on my Roland A-800 Pro midi controller. If it were a dirt problem, it would seem unlikely that they would all go dead that abruptly, and the fact that the high C works fine is curious. Any ideas?
Thanks Ross

Hello Ross, this looks like one on the keyboard matrix connection is not working. Like most keyboards each key is scanned individually as a matrix. In your case the group that has become dead is a line within this, that is eight notes altogether.

I would have a look at the ribbon cable CN1 first which connects the motherboard to the keyboard unit itself.

Regards Darren

Thanks Darren. Can this be fixed by replacing the cable? If so, how can I get one?

It could do, for me, I like to know exactly where the failure is. So probably the cable, but I would also check the keyboard frame PCB.

I’ve checked the service manual but it does not state the exact cable type, you’d probably need to see the cable and get one equivalent. This cable can be sourced from Digipart, Farnell, RS-Spares etc.

I think it’s rare that a cable would “go bad.” Maybe with age, or being handled.

I’d examine the circuit board in the keybed and find the common trace, then run it back and check continuity with the connector. I’d suspect maybe a bad connection that gave out.

Thanks for all the replies. I have made a mistake of messing up the ribbon cable that attaches control surface the power from opening the case too many times. It still comes on but doesn’t function right at all! There is a service center in Gainsville, so I will take it up there next week. Once again, thanks for all the replies!