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NOTE
Users must limit their service to Level 1 during the warranty period.
The Quantum warranty is null and void if the HDA is opened or any
Level 2 procedure is attempted.
All time and material to repair the
drive will be billed at the prevailing rates.
5.3
Level 2 Maintenance
Level 2 maintenance is performed by trained personnel at an authorized
service center or at the factory.
o
Level 1 plus repair of HDA and PCBs.
5.4
Connector Maintenance
Both intermittent problems and solid problems can be caused by con-
nectors.
Before troubleshooting by observing waveforms, inspect the
ribbon cable connector on the SCSI bus: check visually with a 3X to
lOX magnifier that all wires are crimped to the contacts; flex the
cable gently while the drive is operating and watch for intermittents;
clean the contacts by wiping them with a lint-free cloth moistened
with a contact-cleaning solvent.
5.5
PCB Waveforms and Techniques
The waveforms described in this section may be observed for trouble-
shooting: to determine if the PCB is operating correctly, or to
isolate a problem to the board or the HDA.
If a drive successfully recalibrates when operating in a system, the
following waveform tests are not likely to reveal any problems, since
most circuits must operate: power, paR, RAM test, motor control,
microprocessor, EPROM, DICEY, FYLO, seek, servo, read, phase-Iocked-
loop, write, and SCSI interface.
These waveform tests are primarily useful with a drive that doesn't
recalibrate.
They concentrate on read functions; these exercise
almost all circuits and require the least special test equipment.
It is easier to check write functions by noting the Sense Error Codes
and Sense Keys reported to the host over the SCSI bus.
5.5.1
o
Special Test Equipment
150 MHz (or better) oscilloscope with differential input and
two or four channels.
High impedance probes are required,
and a delaying sweep is useful.
5-2
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