It seems that you have a valid System Folder on the drive if it can boot the Mac when the HDD is used as an external startup volume. However, internal and external buses are separate in the 9500.
External bus (including its controller) and termination seem to be functional. Given that the HDD is terminated correctly on the drive, and was not getting termination from the external enclosure, and that the HDD is not only the terminal device in the internal daisy-chain, but also has TP enabled (termination power supplied by the drive, if the HDD has that option) it should work.
It is unlikely, but not impossible, that the internal bus controller might fail, but the internal controllers of two MLBs? It seems rather that yours is a cabling, a connector, a PS (or termination power to the bus), or a position problem. Do both drives, especially the HDD, spin up? Have you jumpered TP (termination power) on the CD-ROM? Can you boot the Mac from the internal CD-ROM?
de
External bus (including its controller) and termination seem to be functional. Given that the HDD is terminated correctly on the drive, and was not getting termination from the external enclosure, and that the HDD is not only the terminal device in the internal daisy-chain, but also has TP enabled (termination power supplied by the drive, if the HDD has that option) it should work.
It is unlikely, but not impossible, that the internal bus controller might fail, but the internal controllers of two MLBs? It seems rather that yours is a cabling, a connector, a PS (or termination power to the bus), or a position problem. Do both drives, especially the HDD, spin up? Have you jumpered TP (termination power) on the CD-ROM? Can you boot the Mac from the internal CD-ROM?
de