IBM 727, Руководство по инструкции

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17. 0 PREVENTIVE MAINTENANCE
The head assembly including the pressure pad, magnetic recording head surface,
tape break cleaner block, split and guide pulleys, and top of the vacuum columns,
should be cleaned at the beginning of each assigned period of customer operation in
anticipation of eight hoursf usage. The pressure pad can be cleaned best with an
IBM typewriter brush (P/N 1018992). The other surface may be cleaned with a lint-
free cloth or cotton tipped stick dampened with a suitable solvent. The vacuum
columns should be disassembled to clean the walls every 40 hours of operation. A
cloth with solvent also does a good job in this operation.
Follow this cleaning schedule strictly to attain maximum tape reliability:
1. Reliability (daily). Establish reliability by use of a suitable program .
2. Reliability (monthly). Establish reliability monthly by obtaining 15 minutes
of e rr o r-fre e operation with a suitable program .
3. Abnormal DC— voltage tests (monthly). Vary the following voltages and ob­
tain one minute of e rr o r-fre e operation at each limit while operating a suitable program .
Nominal Voltage
-60
Recommended Test Limits
-54
-78
-130 -117
-137
+140
+133
+150
NOTE: In case of random tape e rrors that are not revealed in above tests, try
varying voltages in the central processing unit while operating a suitable program .
4. Tape drive mechanism (every shift). At the beginning of each shift of cus­
tomer operation, clean the following: tape head, drive capstans, stop capstans, split
idlers, and moving pulleys, pressure pad and vacuum-column metal tops.
5. Skew test (quarterly). Check for skew using a master tape (P /N 503928)
with either a control unit or a tape drive tester.
6. Interchangeability test (quarterly). Using a suitable program , write 500 feet
of tape on one unit, and check on three other units if possible. In case of trouble,
check for skew, tracking, pressure pad and mechanical adjustments.
7. Am plifier alignment (monthly). Check the pre-am plifiers for proper adjust­
ment. (Any time a tube is replaced, the amplifier should, of course, be re-align ed .)
Check range, pulse width.
8. Special pulses and timings (monthly). Use an oscilloscop e to check the follow ­
ing pulses:
Start envelope End-of-file OR
Stop envelope Tape break single shot
Write pulse Moving coil current
Echo pulse Erase coil current
Load point single shot
9. Vibration test (monthly). Vibration check the tube panel while operating the
unit.
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