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7970B/7970C
Description
SECTION
DESCRIPTION
1-1.
INTRODUCTION.
1-2.
This section describes the transport for the Hewlett-
Packard 7970B/7970C Digital Magnetic Tape Units and pro-
vides a functional description of the transport circuits. Speed
critical assemblies are defined and optional assemblies are
described.
1-3.
PHYSICAL DESCRIPTION.
1-4.
The tape unit consists of a transport casting as-
sembly and a sheet metal housing assembly. The housing
assembly contains the power supply, the power distribution
assembly, the control and status assembly, and interfacing
provisions. The read and write modules are also contained
in the housing assembly.
1-5.
The transport casting assembly consists of all tape
moving assemblies, reel motors, capstan servo motor, ten-
sion arm assemblies and the circuits associated with these
assemblies. The magnetic tape head assembly, photosense
assembly, write interconnect assembly, and read preampli-
fier assembly are also mounted to the transport casting as-
sembly. All standard and optional switch assemblies are
mounted to the transport casting assembly. All assemblies
are accessible and all circuits will operate with the transport
assembly open.
1-6.
SPEED CRITICAL ASSEMBLIES.
1-7.
The tape unit will operate at tape speeds between
10 ips and 45 ips. The actual tape speed of the unit is speci-
fied when the unit is ordered. The following are limited or
critical to tape speed:
a. Reel Motor Assembly.
b. Capstan Motor Assembly.
c. Capstan Servo PC Assembly.
d. Magnetic Tape Head Assembly.
e. Read Modules.
f. Write Modules.
1-8.
REEL MOTORS.
1-9.
Reel Motors B1/B2, part number 07970-60170, are
used on tape units with tape speed ranges between 10 ips
and 37.5 ips. Reel Motors B1/B2, part number 07970-60171,
are used on tape units with tape speed ranges between 37.6
and 45 ips.
Part 2
1-10.
CAPSTAN MOTOR ASSEMBLY.
1-11.
Capstan Motor Assembly MG1, part number 07970-
60140, is used on tape units with tape speed ranges between
10 ips and 37.5 ips. Capstan Motor Assembly MG1, part
number 07970-60141, is used on tape units with tape speed
ranges between 37.6 ips and 45 ips.
Note
Capstan Motor Assembly MG1, part number
07970-60140, may be used on tape units oper-
ating at 45 ips. However, program restrictions
must be maintained.
1-12.
CAPSTAN SERVO PRINTED-CIRCUIT
ASSEMBLY.
1-13.
The capstan servo PCA is equipped with a dummy
connector that functions as a strapping network. The
dummy connector is installed in one of six positions, de-
pending upon the speed range of the tape unit and capstan
motor assembly used. See figure 7-10, Capstan Servo PCA
A9 Schematic Diagram, for details of dummy connector.
1-14.
CAUTION
Ensure that dummy connector is installed in the
proper position prior to applying power to the
unit. Attempting to operate the unit without the
connector installed or with the connector in the
wrong position may result in damage to the unit.
MAGNETIC TAPE HEAD ASSEMBLY.
1-15.
The magnetic tape head assembly consists of tape
guides, a tape cleaner, and, depending upon configuration,
read, write, and erase heads. The tape head assembly is speed
critical; refer to section VI for part numbers and speed ranges
of the magnetic tape head assembly.
1-16.
READ MODULES.
1-17.
The read modules are described in detail in part 3
or part 5 of this manual.
1-18.
WRITE MODULES.
1-19.
The write modules are described in detail in part 4
of this manual.
1-1
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