Theory And Circuit Analysis - GE 4PE350A3 Instructions Manual

COLOR CAMERA EBI-6351
NOTE
The luminance test
pattern is
displayed
with
its
polarity unre-
versed and the chrominance test
pattern with its polarity reversed.
4. Rotate the red yoke to superimpose the
center horizontal line.
5. Adjust the R SKEW control to super-
impose the center vertical line.
6. Adjust the six red channel controls on
the registration control panel to superimpose
the R channel on the luminance channel.
7. Depress the W -B push button on the
viewfinder panel.
8. Repeat steps 4, 5, and 6, using the blue
controls.
9. Depress the W -G push button on the
viewfinder panel.
10. Repeat steps
4, 5,
and 6, using the
green controls.
11. Depress the WRBG push button on the
viewfinder panel. There should be no evidence
of misregistration in a central area equal
to 0.8 of the picture height.
Luminance Aperture Correction
1. Using a wideband oscilloscope, observe
the output of the luminance amplifier, with
the calibration pulse on.
2. Adjust the aperture correction control,
R25, to its mid -position.
3. Adjust the aperture correction balance
control, R31, to its mid -position.
4. Adjust the aperture correction clipper,
R12, so that correction occurs only on. the
top 40 percent of the calibration pulse.
5. Remove the pulse and observe the Res-
olution Chart.
6, Set the iris to produce 0.7 volt on the
white area of the Resolution Chart.
7. Set up the oscilloscope in the line se-
lect mode.
8. Observe the 400 -line point on the wedge
and adjust the aperture correction control,
R25, until the
peak whites are at 100%
(0.7 volt).
9. Observe the W channel on the Camera
viewfinder and adjust the aperture correction
balance control, R31. to produce equal whites
on each edge of the vertical black lines.
10. Recheck the 400 -line point on the wedge
for 100% response and readjust if necessary.
NOTE
The procedure outlined previously
should be used for initial
setup.
Once the Channel has been com-
pletely aligned,
the
picture
and
waveform monitor, Model 4TM22A1.
can be used in place of the os-
cilloscope mentioned previously.
THEORY AND CIRCUIT ANALYSIS
Preamplifier Board, PL -7674511G1, G2
Refer to the
Waveforms, Fig. 15, the
Printed Circuit Diagram, Fig. 16, and the
Schematic Diagram, Fig. 17.
The input stage of the preamplifier is a
cascode configuration using a field effect
transistor, Ql, and a conventional transistor,
Q2, The signal is further amplified by Q3
and Q4 and a negative feedback is applied
to the amplifier input through load resis-
tors R11 and R12. The feedback lowers the
input impedance
of
the amplifier to ap-
proximately
2500 ohms and thus greatly
reduces the amount and time constant of
the high peaking required to compensate for
the input shunt capacity.
Q5 serves as a buffer to drive the re-
mainder of the amplifier. Q6 is an amplifier
stage that incorporates the peaking circuits
required to make the overall amplifier re-
sponse flat to 6.0 mHz. Q7 is another buffer
amplifier and Q8 is an inverting output stage.
The normal output level of the pream-
plifier
is typically 0.20 volt peak -to -peak
into 51 ohms for the luminance and 0.30
volt peak -to -peak into
75 ohms for the
chrominance.
17