I recommend you go with B7T9 unless you have reason not to. Software bugs are always fixed in the more recent revisions, and the development group will not always admit to the fixes. My recommendation would be to run the B7T9.EXE executable file rather than use the "B7T9.CVT" data file, since your drive now thinks that it's a "B" version. And there's always the possibility that the executable might do a bit more than simply updating the drive's firmware.
Next, if you don't already have it, you should download the latest CDSpeed from the following link:
Before using CDSpeed, I recommend you consider changing the "quality check" graph colors from the default "Legacy" color to "Bright" so that you can see the color coding easier, since the color will help you interpret the value of your scan. You do this by clicking menu items "File->Options" and then selecting "Disc Quality" along the left. You'll then see a "Colors" section to the lower right with a pulldown box labelled "Theme". It will have "Legacy" currently selected. Change it to "Bright", and CDSpeed will use different colors in the PIF area (green, light red, and dark red) to help you determine the health of the burn.
At this point you can do a couple of things:
- You can tell CDSpeed to write its own test data to a DVD. You do this by clicking menu item "Run Test->Create Data Disc". By default, CDSpeed will write the disc at its highest speed (8X in your case). Be careful, since there's no warning - the disc burn process will start immediately after you click "Create Data Disc".
This process has a few advantages as follows:
a) It will always fill your DVD with data and hence test out the whole disc.
b) It will write the data independant of other software programs on your system, thus keeping things simple.
c) It will show you the write speed of the data in real time as it's writing, and it will save this write information in one of the many random test files that it will write to. Later, when you do the "Quality Scan", it can retrieve this data and merge the write graph information into the read graph.
d) It will also save the DVD writer name and its current firmware version number on the disc for later retrieval when a "quality scan" is requested.
The sole disadvantage is that this process costs you a disc.
- You can do a quality scan of almost any disc with data written to it. You do this by clicking menu item "Extra->Disc Quality Test..." and then clicking "Start". You should probably leave the Speed setting either at 8X or at maximum (currently the same as 8X). For now, you should probably avoid 16X scanning, since its use is still fairly new and it's somewhat difficult to properly interpret the results.
To be completely sure that your data is good (at least good enough to be read back on your 1620), you could also do a surface scan (as detailed previously in this thread), and it should be completely green for an acceptable disc.
Hope this is useful.