I have a PD 650MB optical drive from Panasonic.(Model#LF-1004H) It will read the disk but when I want to write, it always says that the disk is write protected. I know it is not write protected. Why is the drive can't see it? Any help will be appreciated. Thanks. Andy Kovacs.

On most of these high capacity storage disks, the write-protection is effected by software. Launch the utilities that came with the drive and see if there is a setting for write-protection. Also, if you ever used this disk for a backup using a proprietary backup utility (usually provided with the drive utilities), the utility may lock out any additional writes to the disk. This is the case with ZIP disks and the Iomega backup utility, and it may be so with yours. The third possibility is that there is a defect in the disk or drive write head itself. If a cleaning kit is available for this drive, try using it.

I have had the same problem with my Sony SMO501 650MB drive and oddly it only does it on one side of the disk. I also sometimes get the message disk is not formatted from time to time. I have yet to find the answer.

I've had some fun with this device. I use an Adaptec 1520A SCSI controller to drive a LF-1004H. My collegue has an identical configuration and there's also a machine at work. All three use a Pentium 100 CPU. The work machine uses DOS5 and is utterly reliable. My collegue and I have used Win95 and Win98 and find that you can use the disk fine for a while, then it locks up with the Write Protect error you describe. We've solved the immediate problem by using the works machine to perform a low level format on the disk (i.e. disk is NOT faulty) but, of course, you lose the data! On the Win 9x machines, we've tried cleaning, different disks, different power supplies, updated drivers (Win, Adaptec & Panasonic) with no success - I can't even get Win9x to allow a low level format, I have to boot up in DOS first! I've trawled the support sites for Windows, Adaptec and Panasonic with no real success until I found this site. The fact that my collegue and I both have identical symptoms would seem to suggest a configuration problem and I'm currently chasing the route of trying to isolate a block of memory for the controller to use. To get your disk going again, you'll have to do a low level format though. If anyone out there has an idea on this subject, please let me know 'cos I'm tearing my hair out with this problem!