“Yamaha DX7s Keyboard Digital Programmable FM Synthesizer with Original Cartridge
This keyboard has had the onboard battery replaced with a new separate board isolating the battery from the rest of the circuit board. I read up on it enough to know that the coin battery had a propensity to leak which is why I replaced it with a separate coin battery holder and while I had it taken apart I took the opportunity to clean all the crud out from under the keys and even replaced a few.
The pictures attached show close-ups of the front the keys which are all mostly level. I suppose you could adjust the felt underneath one or two of them if you want to get them to a more precise level.
All 50 of the sound banks work though buttons 14 and 15 require a little more pressure to switch. I cannot test programming because I have no MIDI setup as I am not a musician. One of the reasons I originally wanted to sell this locally was that whoever bought it could test it out before committing to the sale.
The pitch wheel moves the notes up and down as I might expect but the modulation wheel does not appear to do anything noticeable to the note when I move it with a key pressed down. I don’t know if it has to be programmed or if the effect is only on certain sounds or maybe I just don’t have the ear to detect it.” Click here to search for synths on eBay