HP 13255 Technical Information page 38

13255
Cartrldge Tape Module
13255-910j2/36
Rev AUG-Ol-16
dzimuth adjustments are independent of one another. The vertical head
position is controlled
by
maintaining close tolerances on the head and
head bridge, and thus no height adjustment is required. The spherical
bump is also within
+/-0.001
inch with respect to the locating pins
molded into the head bridge. This accurately controls the fore and aft
position Of the head to maintain the proper tape-head wrap angle. Once
set, the head adjusting screws arp sealed in position and no further
head adjustment is required either at initial assembly Or dUrinq field
replacement. Thus any head bridge assembly wOrKs interchangeably with
any base assembly.
3.3.2.3
The head bridge assembly also includes the Cartridge Electronics PCA
(detailed in section
3.2)
which performs various functions. Circuitry
tor sensinq the position holes in the tape is included on this board.
The infrared LED liqht source for this function is retained and pre-
cisely positioned by a molded-in clamp taking advantage of the strength
and
~imensional
stability of the plastiC material used In the
h~ad
bridge to grip the LED without additional parts or machining. Car-
tridge insertion and the position of the
R~CORD
tab on the cartridge
are sensed by the position Of two switches. Fixed contact pads for
these switches are on the circuit board while the moveable contacts
with their plunger actuators are enclosed within the head bridge giving
inexpensive, reliable, enclosed switches.
3.3.2.4
The indicator lamp (previously mentioned) is also located on this
peA
and is enclosed bV a Shield molded of titanium-dioxide filled plastic
for maximum reflectivity. This part serves the dual functions of
blOCking stray light from the lamp While concentrating the light
entering the light pipe portion of the release button. Since all in-
terconnections are made on the board, no wiring harness is necessary
on the mechanism.
3.3.3 MOTOR/TACHOMETER ASSEMBLY - CTU TRANSPORT ASSEMBLY.
3.3.3.1 The third subassembly of the rTU Transport is the motor/tachometer
assembly Which consists of a motor with drive capstan, a motor mount
and a tachometer to provide velocity feedback to the servo.
3.3.3.2
The motor/tachometer assembly is single axis gimballed about its center
of gravity to eliminate acceleration effects on the force developed be-
tween the motor capstan and the belt capstan in the cartridge. This
force is provided bY two exiension springs which also serve to retain
the assembly in the gimbal and to aid in ejecting the cartridge. The
force between capstans is
15 +/·1.5
ounces. The gimbal consists s1mply
of two hemispherical ball and socket jOints between the motor/tachome-
ter assembly and the base assembly. The assemblies are held together