[sdiy] DX7s failed recovery after dead battery

[Rutger Vlek]

Dear all,

I'm hoping for a little inspiration and/or expertise from someone here, as I ran into a strange problem with a Yamaha DX7s (yes the S version).

It displayed a dead battery sign, and I've replaced the battery with a fresh one. The message is gone, and it boots correctly. Of course the original memory content was scrambled due to the lack of battery power, so I tried uploading new patches via Sysex. I've tried many different ways of doing this, and the synth receives them, stores them to memory, and I hear differences in the sounds that I can recall. However, all patches suffer from the same problem. A huge amount of vibrato is added, and pitch scaling over the keyboard is often out of tune or randomized. I tried manually programming a patch (in the memory buffer, didn't try storing it yet), and this worked fine. I tried modifying the loaded patches and found strange parameter values for some modulation indeces that caused the vibrato and key scaling to be off. I found values of 15 where my slide and buttons only allow me to enter up to values of 12! Clearly, something goes wrong in receiving the SysEx and putting it to memory, but I can't figure out what.

I tried 3 different programs, from a plain SysEx dumper to a more fancy DX editor/librarian. I tried from both Windows and Mac machines. I tried through 2 different midi interfaces (both MOTU). I tried various sources on the internet for the SysEx files, at least 5 different sources. So I'm beginning to think it's an internal problem, and nothing to do with the Sysex itself.

Other MIDI messages are received correctly (e.g. note on/off, controllers, etc).

Any ideas?

Best,

Rutger