24x CD-ROM problem on SuperMac computers

Kennedy Brandt (of SuperMac) describes and issue concerning the 24x CD-ROM drives that came bundled with SuperMac computer models:

Trying to boot a SuperMac S900i/250 and a J700/233 from the TechTool Pro 2.0.3r1 CD will cause the machine to completely freeze at startup before even reaching the Happy Mac icon. Also, if these computers are allowed to fully boot and the CD is then inserted, FWB CD-ROM ToolKit (which we bundle with the SuperMac computers) produces a warning message about 512 byte blocks being specified when in fact a different size is in use on the CD. These same symptoms may also occur with custom-burned bootable CD's one might make with, for example, Toast 3.5.4.

The cause of the problem, we've deduced, is that the 24x Matsushita model CR-508 CD-ROM drive used in later-model SuperMac computers has a setting on the back for "Sector Size," and this setting is jumpered. When so configured, the computer will exhibit the above symptoms. If the "Sector Size" jumper is simply removed, the symptoms do not occur and the TTP 2 CD is bootable, just as it should be. We have yet to encounter any problems caused by removing this jumper. Again, this issue will most likely exist with any SuperMac computer that has that 24x CD-ROM drive, as the Matsushita CR-508 is the only 24x CD-ROM drive we've ever bundled.

The only remaining concern is that,while the "Sector Size" jumper is relatively easy to access in our J700 desktop systems, it's virtually unreachable in the S900 tower case unless one first removes the CD-ROM drive, which may entail that one remove the entire drive bay assembly as well.