No display from the LCD on my Yamaha DX7

by Jose Tuero
(Hallandale Beach FL USA)

Hi everyone,
I was wondering if anyone else has had the misfortune
of flipping the switch on their old Yamaha DX7 synth. and notice that there is no longer any display visible on the screen!
This happened now to long ago when sitting down to play and when I flipped the switch; lights came on, patch cartridge lit up and the two 7 segment LED's were showing a number but no visible display could be seen from the LCD screen. Before I start sticking my fingers where they don't belong, I ask in the hopes that someone has run across this same problem and have found what it was.
It's been a good keyboard for the time I have owned it
and I would hate to get rid of it just because there is no fix for it.
Thank you all for your time in reading my question.
Regards
Jose