This is the Yamaha TX7. It’s the module version of the DX7. It was the first synthesizer I ever bought, 28 years ago. It still works perfectly.
But I wanted to replace the display as it is hard to read because it is not backlit. So I bought a display replacement from eBay.
I opened up the case and carefully removed the original display. If you work carefully this is not very hard to do. Next step was mounting the new display and connecting the wires to the main PCB. There is a small pot to adjust contrast to your liking.
After a quick test to check that the synth was still working, I closed the case again. My TX7 now has a shiny bright new display which is easy to read, especially in darker surroundings.