Yamaha PSR S710 Function board buttons not lighting up while powered on

Hello Guys :wave:

I have a Yamaha PSR S710 keyboard that the light on the function buttons went off and none is working again.

You can’t select voice neither do anything on the function buttons. But the keyboard dispaly the screeb memu while powered on.

Please Guys what could be the issue?
And what’s the possible solution to this?

Picture is attached.

Thanks for your help ao far.

You’re going to have your work cut out for that one.
First of all need to open it up - you need a large work area. Lay it on a soft surface top down and remove all the bottom screws - then turn it over and lift the top off the bottom and lay it on the rear of the bottom half. There are lots and lots of cables going from the boards with the switches to a central board on the left of where the screen is ( screen not visible from that view as it is behind the main board) - that is the EIF board - it controls the switches and LED’s. The EIF board communicates with the main DM board to exchange info from buttons pressed and LED’s to be lit up.

First just check all the cables - maybe even remove and re-seat them. Then move the top back over the bottom and try - no need to put any screws back in.

If that does not solve anything it will get difficult

For information - this is the block diagram of the PSR-S710 - each square representing a circuit board - you are looking mainly at the top left section where the EIF board is and all its connections to the various panel circuit boards.

Thank you so much for your assistance, you don’t know how much this mean to me right now.

I think i will systematically follow suit by starting with checking with the cables. I saw some flexes damaged. I will replace them first and replug the wires.
I will then see if this will fix the issue.

Thanks so much, i will get back here.