I just purchased a Lite-On LH-20A1HX external DVD burner from Newegg. I bought this for a friend who has a laptop with a dead optical drive. After looking at the results people were having with the internal LH-20A1H, I thought this drive would be a good deal and save me the trouble of finding separate drive and enclosure that would get along well.
Well, for my first burn, I decided to try putting a movie backup on my last blank Taiyo Yuden (TYG03) at 20x. USB obviously cannot feed the drive quite that fast, so I was not expecting good results. The write process finished after something over 7 minutes – not that good for a drive claiming to be “the fastest DVD Writer in the world.” I never noticed the drive fall back to a lower speed, however, so you can only imagine how much starting and stopping the thing was doing. Now, while I was expecting bad, I was not expecting unreadable. But that is what I got. At around 2.5 GB, CD Speed gave up on the transfer rate test. Later I did a PIE/PIF test with the drive and the results were not pretty at all…
I didn’t think [i]too[i/] much off this because of the massive buffer underrun problem.
Well, the next day the Verbatims (MCC004) I ordered arrived, and I began testing with them so I could be sure the drive would receive data fast enough to prevent any buffer underruns at 16x. It certain did, the buffer meter in CD Speed stayed above 95% to the finish, and the plot was a nice, smooth arc. This chart is from trying HyperTuning. The plot with HyperTuning off lacked the stalactites.
Now, without any drops in performance during writing and with the excellent results people have been getting using the MCC004 media with the LH-20A1* drives, I figured on a very nice, low and consistent PIE/PIF graph. That turned out not to be the case however. While the scan started off great, at around 3 GB the PI Failure rate became horrendous, and the PI Error rate jumped noticeably as well (though it did seem comparatively low for such a dramatic PIF increase).
The transfer rate curve showed a corresponding drop at that point on the disc as well.
I tried a few test burns at 16x and one at 12x with the same results, though with some problems were more pronounced than others. My LG drive read the above disc without trouble, but another was bad enough to cause severe problems.
At 8x the problem did disappear and drive produced an scan, but I didn’t buy this drive and media to settle for 8x burning.
The drive seems to read discs well enough. These are the results are from a disc burned with an LG GSA-H22N (I bought it at the same time) at 18x and scanned with the Lite-On.
The only problem is a small dip near the beginning of the curve. The drive seemed to always have trouble here (high speed quality scans showed lots of PI problems there too).
After making a small stack of coasters (even if they were readable, they are still useless), I was feeling a bit depressed. As I gathered the test discs from my desk, I glanced at the data side of one disc which brings me to the point of this post.
There is a blemish near the outside edge, around where the 3 GB mark should be. In the photo (done with a flatbed scanner in greyscale) the blemish is in the top left quadrant about half an inch from the outer edge of the disc and 50 or so degrees from horizontal.
Instead of merely ascribing this to a defect in the media, I examined all of the other test discs I had made so far. The same anomaly appeared on all five discs written by the Lite-On including that TYG03 done at 20x. One disc even had two instances separated by about 30 degrees.
Visually examining the discs as well as I could without magnification, it seemed as though the data in that area was not written as strongly/distinctly, as though the laser lost focus or power for a brief period at that point.
I don’t know enough about the physics specific to DVD writing to figure out why this sort of problem is occurring. Common problems with writing to to a disc seem to always result in more pronounced rings in the finished disc. Why the problem always happens at the same region on different discs and how it lines up at the same angle on the disc through dozens of passes, I do not have a clue.
I supposed if I had to guess, I would say there is a sort of harmonization occurring between the laser focusing and the wobble/vibration of the disc resulting in the laser losing focus for a few microseconds. A destructive interference sort of thing. But again, I don’t have enough knowledge and am totally clueless.
I am hoping someone here will be able to shed some light on the cause of this problem and perhaps make me feel better about getting a replacement.