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The Set: Pete Deksnis's Site about the CT-100

Restoring a Vintage Color Television Set

The Solution:

The reason for the failure of this set to reproduce 100-percent saturated primary colors is still a challenge. When the set is set up as noted in the preceding page, the 100-percent primary red or blue or green is not reproduced. The cause is probably not in the video amplifiers or the CRT itself, but rather an accumulation of errors, some sort of receiver-based incidental phase distortion if that's even possible, or the result of some guy diddle-sticking the cans in 1956. The color picture looks fine as is, so if this problem goes unsolved, there will be no lack of enjoyment viewing this restoration. The search continues...

Added 11-22-05: In the last 48 hours, a pair of additional facts has emerged:

The 100-percent red screen will appear with extreme fine tuning; that is, from the point of normal color reproduction, the fine tuning control is advance CW to the point of noise, noise, noise. Just at the point that the picture is lost in noise, the screen goes red.

Secondly, I have publicly questioned the efficacy of an NTSC converter/generator found in consumer electronics equipment, and my preference has always been an over-the-air signal when testing and evaluating a CT-100. (The converter/generatorI use is in a late model S-video VCR, fed baseband through an S-Video link from a DVD player.)

Whenever I switch from a channel-4 over-the-air signal to a channel-4 signal from the S-video VCR, the fine tuning of the CT-100 must be readjusted with what amounts to be a major rotation of the fine-tuning knob. Clearly, the f
o of the VCR generator is not normally going to be offset enough to account for the difference in fine tuning.

For me at this point, the prime suspect in this adventure is now the converter/generator in the VCR, and it must be either convicted or exonerated of responsibility.
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