8
performed.
A stable frequency counter capable of measuring up to at least 15MHz, a standard NTSC waveform monitor and vector
scope, and an AC voltmeter are required to adjust the CSG-50.
Note that the VIDEO LEVEL control permits minor adjustment of the video level and is set at the factory for an output
amplitude of 1 volt. Although not recommended unless you have ready access to a NTSC waveform monitor (or
oscilloscope) for re-calibration, the VIDEO LEVEL control can be used to compensate for slight amplitude variations
resulting from cabling and termination values in your system.
To access the adjustments, remove the bottom cover from the CSG-50 by removing the two screws from the front panel
and then sliding the bottom cover out towards the front.
If you have a Rackmount or Shortrack packaged CSG-50, remove the four screws from the top cover and remove the
cover.
All adjustments are located on the circuit board as shown in Figure-3.
C37 +
R23
+
C26
+
+R11
Figure-3, Adjustment Locations
5.4 Chroma Frequency Adjustment
Frequency Counter Method
1. Connect a frequency counter to monitor U6 pin-8.
2. Adjust C26 for a frequency reading of 14.318/-10Hz
Off the Air Method
The frequency of the CSG-50 master oscillator can be set very accurately by using off the air television broadcast signals.
1. Connect the CSG-50 Video Out through a BNC "T" connector to the input of a video monitor.
2. Connect the composite video output from a TV receiver/monitor or tuner to the other input of the "T" so that the two
video signals mix and are simultaneously displayed on the monitor. Alternately a monitor with separate A and B video
inputs and a "mix" display mode can be used.
3. Set the TV channel to one of the major networks.
NOTE:
For best frequency accuracy, make sure you are viewing a
network originated signal. Generally, a locally originated signal, such as from cable services, colleges, etc. may not be
as stable as that from a major television network.
4. The TV monitor will "lock up" to either the CSG-50 or the off air signal, sometimes switching back and forth between
the two. There will be a relatively dark vertical bar going from top to bottom of the screen and it will appear to be
stationary or to be moving slightly from left to right or from right to left. The bar will also have a colored stripe in its
right half, and the stripe will be continuously changing colors.
5. Carefully adjust C26 for minimum movement of the bar across the screen, and then for the slowest change of the
colored stripe. It should be possible to have the stripe go through all its colors only a few times a second or less.
Switch CSG-50 power OFF and ON if necessary.
5.5 Video Amplitude and Equalization
The video level is set at the factory for an output amplitude of 1 volt. Whenever the video amplitude is adjusted, the video
equalization should also be adjusted.
Содержание CSG-50
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