Hp 7925H Mainframe Assembly - HP 7925D Service Manual

Appendix A
A-79. OPERATING MODE. Self test will be
started at power turn on and will run through the self-test
sequence until a test requiring a "drive ready" state is
incurred. A flashing octal 10 will then be seen on the
TEST RESULT LED's. When the disc drive RUN/STOP
switch is set to RUN, the sequence described above will be
repeated. When the spindle comes up to speed, the heads
load, and the internal time delays have lapsed, "drive
ready" will occur, and the self-test sequence will complete.
A similar sequence can be initiated by HP-IB command, or
by the START switch on the self-test panel. At the begin-
ning of self test, the TEST RESULT LED's, the S.T.
FAILED LED, and the operator panel SELF TEST
FAILED indicator will flash briefly, indicating controller
activity and testing of the LED's. If a test fails, the test
number (octal) is displayed continuously on the TEST
RESULT LED's. A test failure summary, including prob-
able failure sources is provided in table A-9. The S.T.
FAILED LED and the SELF TEST FAILED indicator are
also lit continuously if a test fails. If no failures are de-
tected, all self-test readout remains off.
If an error occurs on tests 17 through 15, the controller
"hangs" (HP-IB command sequences are not recognized
and the self-test panel switches are inoperative). If an
error occurs in tests 14 through 3, or if there are no errors,
self test exits to the controller operating firmware where
the HP-IB sequences are recognized. The secondary se-
quence RETURN SELF-TEST RESULT should be exe-
cuted before any disc drive commands are attempted in
order to learn of any self-test failures.
All other disc drive indicators and controls, including the
DRIVE FAULT and DRIVE READY indicators, and the
RUN/STOP switch are not affected by self test. Drive
ready is not inhibited by a self-test failure.
A-BO.
SERVICE MODE. In the service mode, the
controller loops continuously on the test number set on the
TEST NUMBER switches until the first error is detected.
If the TEST NUMBER switches are set to zero, the con-
troller loops on the entire self-test program.
If the controller is looping on a single test in the service
mode and an error is detected, the section number of the
failure is continuously displayed on the test panel TEST
RESULT LED's.
If
the controller is looping on all of self
test (TEST NUMBER switches set to zero), the test failed
number is displayed continuously. Whenever a test is suc-
cessfully completed when in the service mode, the TEST
RESULT LED's flash the appropriate test number to indi-
cate which test the controller is executing. When looping
on all of self test, the TEST RESULT LED's continually
count down through the test numbers.
A-81. SELF-TEST EXAMPLE
The following example is provided to illustrate the man-
ner in which a circuit malfunction - an intermittent fault
in the formatter/separator data path - is isolated by
A-38
7925
means of self test. First, it should be noted that intermit-
tent faults may not cause a self-test fail at power turn on,
especially if the problem is temperature related. There-
fore, if a drive fault is suspected, it is recommended that a
continuous loop on self test be initiated. This is achieved
by a) setting the OP/SERVICE switch to the SERVICE
position, b) setting all of the TEST NUMBER switches to
zero, and c) activating the START switch. In the event
that the system is not in Idle State 2 or 3, Idle State 2 can
be entered via the END command. The controller will now
loop on self test, with the TEST RESULT LED's counting
down the test numbers until an error is detected. The
TEST RESULT LED's will then continuously display the
errant test number and the self-test failed indicators will
be lit. For the sample malfunction, an octal 12 will be
displayed, indicating a formatter/separator loopback test
failure. Details of this test are given in table A-B. By
setting the TEST NUMBER switches to 12 and again
activating the START switch, the controller can now be
made to loop on the formatter/separator test until a failure
again occurs. This time, when a failure is detected, self
test will halt with the TEST RESULT LED's indicating
the sector number of the failure - in this case an octal15.
From table A-9, it can be determined that the data sent
through the formatter/separator is bad and the probable
source of the malfunction is data peA-Al.
It is possible to continuously loop on a section failure by a)
selecting the service mode, b) setting the TEST NUMBER
switches to the failed section number, and c) holding the
START switch in the on position. This allows the failed
test to be repeated after it is detected - a useful feature
when troubleshooting the circuitry with an oscilloscope.
A-82. TROUBLESHOOTING
FLOWCHARTS
The following troubleshooting flowchart is revised for use
with the HP 7925H and replaces figure 4-1 in the main
manual.
• Figure A-13. HP 7925H Power-Up Troubleshooting
Flowchart
The remainder of the troubleshooting flowcharts in the
main manual are applicable to the HP 7925H. The revised
functional diagrams listed in paragraph A-B6 should be
used with these flowcharts.
A-83. POWER SOURCES
The following schematic is revised for use with the HP
7925H and replaces figure 4-23 in the main manual.
• Figure A-15. HP 7925H Mainframe Assembly
Wiring Diagram