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AST RESEARCH, INC.          TECHNICAL BULLETIN # 1145               4-18-95

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				TERMINATION NOT DISABLED ON QUANTUM 1080S


PROBLEM

Systems using the Quantum 1080S SCSI Hard Disk may experience disk failures 
or other intermittent problems related to termination.  These problems could 
include disks dropping off-line, shadowed drives, and SCSI bus time-out 
errors, especially when the SCSI sub-system is under heavy use.

CAUSE

Although the TE (Termination Enabled) jumper (J13) is removed, the bus lines 
are still terminated through an AC termination circuit.  Due to this 
condition, the hard disk remains terminated when the jumper has been removed.  
The resistors located next to the TE jumper must be removed to ensure proper 
operation.

SYSTEMS AFFECTED
AST PART NUMBER AND DESCRIPTION                        REVISION
501530-XXX          Manhattan G560                     Model 1003
501500-XXX          Manhattan V5090                    Model 1003
501502-XXX          Manhattan P5090                    Models 1003E & 2003AE
500872-009          HDISK 1.0GB FastSCSI w/ rails      Option Kit
500872-013          HDISK 1.0GB FastSCSI w/tray        Option Kit

SOLUTION

In order to properly remove termination from the Quantum 1080S drive, both 
the TE jumper at location J13 and the terminating resistors located next to 
the TE jumper must be removed from the drive. Documentation indicates that 
only jumper J13 needs to be removed in order to properly remove termination 
from the drive.