Quadra 900 & 950: Internal Hard Drives Must Not Be Terminated


Internal hard drives on the Quadra 900 & 950 must NOT be terminated. All Apple and third-party internal SCSI drives have terminating resistors that must be removed before installing in the Quadra 900 & 950.

If an internal hard drive is terminated, it will likely damage the Quadra 900 & 950's logic board. This occurs because the Quadra 900 & 950's logic board has active SCSI termination. If a SCSI device is installed with terminating resistors, it will overload the SCSI chip on the logic board and probably cause it to fail. Adding more SCSI devices will increase the load on the SCSI chip and make the failure more likely.

This situation is noted in the Technical Procedures for the Quadra 900 & 950 on
pages 1.6 and 2.11.

Article Change History:

29 Nov 1994 - Reviewed and updated.
26 Jan 1993 - Updated to include the Quadra 950.

Support Information Services
Published Date: Feb 18, 2012