I have a MDV630RW & an MDV650 as well. In the past I've used several kinds of disks with success. Recently when running low on disks I've found that 1-4x DVD+R disk are getting hard to find. I've had some problems recording on higher speed disks so I did some checking and updated my firmware to version ff12t (which is suppose to improve burning on higher speed disks).
Well, not only did this not really help burning on higher speed disks (16x disks won't burn at all and the 8x brands that I previously used successfully won't either-about 50% failure rate on them) now, some of the disks that were burned & played on these recorders won't play on them (Magnavox in particular). The disks still play on my portable player.
I found some1-4x DVD+R disks on eBay that I've previously used, and now I can't record on them (they record but with about a 75% failure rate). My Dvd+RW disks from TDK work fine, and the few 1-4x DVD+R disks from Ridata work great, but I can no longer find them.
Does anyone have any feeling if I should install an old version of the firmware & if so which one? Or maybe a source for Ridata 1-4x disks. I've found a couple sources for 8x ridata, but as I'm accumulating a lot of disks already that won't work, I'm getting gun shy.