b . S l o w a x i s c o n t r o l l o o p .
Consists of the following components circuits.
D i f f e r e n t i a t o r C i r c u i t
Slow Axis Integrator
Exposure Index Circuit
Slow Axis Raster Edge Control
Slow Axis Toggle
Reset Network
Run/Stop Flip-Flop
Blanking Network
(1) The input to the slow axis control loop is from the fast axis toggle
which consists of a series of positive and negative pulses. These positive and
negative pulses are applied to the input of a differentiator consisting of C11,
CR16, CR19, and R500 on the printed card chassis.
The differentiator produces a
positive spike when the input level changes.
The amplitude of these positive spikes
has one of three levels as determined by the EXPOSURE INDEX switch setting. The
largest amplitude occurs for an EXPOSURE INDEX switch setting of 10 and integral
m u l t i p l e s o f 1 0.
An intermediate amplitude occurs for a setting of 12.5 and
m u l t i p l e s o f 1 2 . 5.
The lowest amplitude occurs for a setting of 16 and integral
m u l t i p l e s o f 1 6.
( 2 ) T h e d i f f e r e n t i a t e d o u t p u t i s a p p l i e d t o t h e s l o w a x i s i n t e g r a t o r w h i c h
consists of operational amplifier Al and current amplifiers Q3, Q4, Q5, and Q6 on
slow axis deflection card 3D2.
The slow axis integrator converts the pulses into a
staircase current through CRT yoke L101B and R37.
The horizontal portions of the
s t a i r c a s e a r e c a l l e d “ t r e a d s ” a n d t h e v e r t i c a l p o r t i o n s “ r i s e r s . ” W h e n t h e i n t e g r a-
tor receives a positive pulse, the output is stepped down (riser). The interval
between input pulses, which form the tread, is the time of the fast axis sweep. The
staircase current produces the slow axis sweep which moves the spot along the slow
axis at the end of each fast axis sweep.
The voltage across R37 on card 3C2 is
applied to the slow axis raster edge controls on card 3CC1.
(3) The exposure index circuit consists of C104 thru C111, EXPOSURE INDEX
switch S108, EXPOSURE INDEX VERNIER switch S102, and vernier resistors R139 thru
R147.
Changing the setting selects different values of capacitance for the exposure
of the negative.
The value of capacitance determines the rise in the slow axis
s t a i r c a s e .
The larger the capacitance, the smaller the step and, therefore, the
more scans per square inch over the complete raster. As the number of scans
increases, the time it takes to completely expose the negative increases.
Exposure
index can be varied to produce any exposure pitch from 10 to 1000 scans per square
i n c h .
EXPOSURE INDEX VERNIER switch S102 adjusts the exposure control in five
percent increments.
9-10
TM 5-6675-319-14
