| The Set: Pete Deksnis's Site about the CT-100 Restoring a Vintage Color Television Set |
The Search:
Based upon picture settings described next, a test of the reproduction capability of the set for each primary color at 75-percent saturation yields:
Determine Control Settings:
Front panel color, contrast, and brightness controls are set CCW. When the brightness control is varied from end-to-end, it swings the red grid between 0 and 70 volts dc as shown in the lower, dc-coupled 50 V/cm vertical sensitivity traces below.
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With the brightness at maximum (70 Vdc) the G2 control setting produce a moderately bright raster as seen in the right-hand image, above. [Vintage documentation sets the brightness control slightly lower when G2 adjustments are performed.]
When the brightness control is set for one-half its full swing, or 35 Vdc, the contrast control is rotated CW to locate the point of red-gun signal clipping (below). Under these conditions, the red gun signal clips at about 150 volts p-p.
However, the dc restorer keeps sync tips fixed until the red video reaches about 100 volts p-p. Accordingly, the contrast control is set for a 100-Vp-p red video signal.
Review:
Brightness is adjusted for a 35-volt dc level at the red gun,
then the contrast control is adjusted for a 100-Vp-p video signal at the red gun.
Color is added by advancing the color control. Except for the presence of an I signal as seen on the upper scope trace, no changes are evident.
To continue, click on [The Solution] next.