BK Precision 1249B, Instruction Manual

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37
MAINTENANCE (CONT.)
2. Press the NTSC BARS switch and release the COLOR
OFF switch. Set the Waveform Monitor for a sweep
speed of 1µs/div.
3. Adjust VR10 and VR11 on the 1249B for minimum
ripple on the bottom edge of the sync pulse. Repeat until
no further improvement is possible.
Color Adjustments
1. Adjust the vertical and horizontal position controls on the
Vector-scope so that the dot is exactly centered on the
screen and make sure that the gain control is adjusted for
sync pulse amplitude of - l 0 IRE.
2. Press the NTSC BARS switch and release the COLOR
OFF switch on the Generator.
3.
Adjust VR12 on the NTSC Generator to align the burst
vector with the mark on the horizontal axis of the
Vectorscope. Readjust the phase control on the
Vectorscope if necessary.
4.
Adjust VR4 and VR9 on the Generator to bring the red
vector into the small R box on the Vectorscope display.
5.
Adjust VR6 to bring the blue vector into the small B box
on the Vectorscope display.
6. Adjust VR5 to bring the green vector into the small G
box on the Vectorscope display.
7. If necessary, readjust VR12 to align the bunt vector
with the proper mark. Also if necessary, readjust VR4,
VR5, VR6 and VR9 to bring all six vectors into their
proper boxes.
8. Return the Waveform Monitor sweep switch to 2H and
adjust VR7 on Generator for grey level
of 77
IRE on the
Waveform Monitor. Recheck Vectorscope display and
readjust vectors if necessary.
9. Release all of the pattern selection switches (the four light
colored pushbuttons) by slightly depressing one of them.
With the Waveform Monitor sweep switch still set on 2H,
adjust VR20I on the Generator for a white level of 100 IRE
units on the Waveform Monitor. Engage the
NTSC BARS
switch.
10. Adjust VR2 on the Generator so that the black color bar the
last one) is 2.5 divisions wide on the Waveform Monitor. If
waveform jitters, readjust VR2 slightly so that spacing is
between 2.5 and 2.0 divisions.
11. Press the LINE and 7 X 11 switches on the NTSC
Generator. Adjust VR3 so that the top horizontal line of the
Waveform Monitor display is at 100 IRE.
12. Adjust VR1 fully counterclockwise. If the tops of the
vertical lines on the Waveform Monitor display are not at
100 IRE, adjust VR1 until they are.
INSTRUMENT REPAIR SERVICE
Because of the specialized skills and test equipment
required for instrument repair and calibration, many
customers prefer to rely upon B&K Precision for this
service. We maintain a network of B&K Precision
authorized service agencies for this purpose. To use this
service, even if the instrument is no longer under warranty,
follow the instructions given in the WARRANTY SERVICE
INSTRUCTIONS. There is a nominal charge for instruments
out of warranty.