If you have an older synth, try this which covers a lot of models, and it just might suit you.
If the synth you have is in here, you can create a new ins for just that synth from this file too, simply by deleting the unnecessary stuff. You do have to be careful not to delete any needed text for it to work, and I haven't done this in years, so I'm afraid I can't help with that!
Roland.ins