HP 28642A manual Scsipba and Centpba Diagnostics, Troubleshooting Checklist

SCSIPBA and CENTPBA Diagnostics

Standard diagnostics,scsipbaandcentpba, are available for useby authorized service personnel. For more information on thesediagnostics,refer to the systemtroubleshooting and diagnostic manuals for your particular system.

Troubleshooting Checklist

Table 2-l provides a troubleshooting checklist that canbe usedto help identify faults.

Table 2-l. Troubleshooting Checklist

Check list item

Are all connectors (SCSI andparallel) properly and securelyfastened?

Are all the external devices operating correctly?

Explanation

Marginal connections can causeimproper operation. Ensure that the adapter and retaining screwsare completely engaged. Check all cableconnections.

Run their self-testsand verify their settings.

Doeseach device on the SCSIbus have a unique address(0 through 7)?

Are SCSI bus length and cable requirements met?

Usually, there will be a set of switcheson the device. Conflicting addressesmay causeintermittent or complete failures in transmission.

Minimize the SCSIbuslength. Do not exceed6 meters, which includes cable lengths inside eachperipheral (the SCSI/parallel adapter’s internal SCSIbus length is 0.1 meter). However, do not usedevice-to-devicecablesthat are shorter than 0.5 meters.

Are you using HP cables?

Do all deviceson the SCSI bushave the same parity-checking capability?

HP cables are wired to minimize noise.

If any device on the SCSIbus doesnot generateparity, no deviceon that bus maycheck for it A mismatchcauses non-recoverable hardware errors becauseparity is both expectedand missing. (Note: Only somevery early SCSI devicesdo not generateparity.)

Service Information 2-f