IBM 727, Руководство по инструкции

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The other way to initiate a rewind operation is from the load-rewind button on
the front panel. This button in 75.09. 02 brings up "manual load rewind" which com ­
bines in 75.08 with "read status" to bring up "rewind PU re la y ." "Read status" is
used because, if the unit were in write status, the read-w rite and erase heads would
conduct and information would be destroyed as the tape was passed by these heads.
11.14 FILE PROTECTION
If a file-protection ring is placed in the groove of the file reel, the sensing pin
is forced to the rear. This operates the file-protection relay armature and the AL
points close. This closing causes the relay coil to be picked (75. 09. 06) and to hold
as long as the reel is on the machine and the door is closed.
The file-protection relay BL points (75. 09. 01) transfer to bring up the "not file
protection" line through R22-2, R31-3, R35-3. This line goes to 75.02 where it is
combined with the right output of the re ad-write-status trigger to produce "write
status." If the ring is not in the groove of the reel, the relay is not operated and
"not file protection" is down. The n /cB L points cause the file-p rotect light to be
turned on. When "not file protection" is down, writing and erasing are prevented.
11.15 FORWARD AND REVERSE SWITCH
A customer en gin eers tool is provided for manually controlling the forward or
reverse motion of tape. The tool consists of two push buttons that may be connected
through a cord and Jones plug to the machine. The connection is shown on 75.09. 01.
If the forward button is pressed, R34 is energized which in turn brings up the manual-
start line (75.09.02). If the reverse button is pressed, R33 is picked and the man­
ual-rev ersé line is brought up (75.09.02) to reverse the forw ard-reverse magnet
assembly. Also, R33-1 picks R34 to bring up "manual sta rt."
11.16 MACHINE READY 75. 09. 03
The machine-ready line is up, and the ready light is on if R20 and R18 are picked
and R36 is down. To accomplish this condition, the start key must be pressed to pick
R20. The run relay R18, when picked, indicates a closed door, no blown fuses, no
broken tape, DC power available and vacuum motor up to speed. R36, rewind status,
when down, indicates the unit is not rewinding. The ready line must be up in order to
perform such operations as read, write, backspace, or rewind from the control unit.
11.17 RESET 75.09.04
Pressing the reset key picks R30. The R30 points take the machine out of ready
status and, in general, stop any tape operation that has been initiated (section 20. 0).
11.18 REEL ARM LATCH
The reel-arm latch magnet (75. 09. 06) is energized whenever the door is open.
When energized, the latch pin is driven forward to prevent the reel arm, once lifted,
from falling. This is for convenience in loading and unloading the machine reel.
When the door is closed, the latch magnet is de-energized, the latch pin returns un­
der spring, tension, and the reel arm falls into place.
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