21CT55 #2628 restoration

[Penthode]

The line I believe is actually due to the other end of the sync pulse. Consider this: the other end of the sync pulse is approximately 4.7us after the horizontal sync trigger. This falls within the active picture in the middle during the horizontal retrace period and if not properly controlled, will induce a vertical white line.

The factors which induce its appearance include IF alignment or video amplifier response in conjunction with the sync generated in a DVD player perhaps having too sharp a risetime. If the overall TV's video response is not reasonably flat, this will cause an overshoot into white which shows up as a white line.

Earlier sets did not have retrace blanking which makes this more problematic. The solution is careful check of the overall video RF and more particularly the IF response.

Color chassis's and the CTC2 chassis in particular is tough to align if you do not have the correct equipment. Fortunately good equipment is available on Ebay at a reasonable price. I trust you will find better equipment.

Forty years ago when I dismissed the thought of ever acquiring Hewlett Packard test equipment to do the job. Back then, at $5K to $10K, 1970's HP equipment was certainly out of the question. In the last 10 years, (thanks to Ebay) I picked up a 1970's HP8601a and HP8600a together for less than $100. I have used these devices to align sets RF, IF and chroma sections to and often I feel more accurately to factory specifications.

Alignment can be tough and is impossible without adequate equipment. But doing it right with the right equipment always rewards your efforts.

Originally Posted by Zenith6S321

I notice that turning the contrast all the way down removes the vertical white line. I can then turn the brightness all the way up with no line.

If I connect the Heathkit vectorscope and use its switches to disable the CRT grid video I do not see the line. Just connecting the vectorscope leads to the CRT grids reduces the white line quite a bit. Maybe high frequency ringing occurring during the horizontal retrace somehow coupling into the video?

I am using three modern 120 mH peaking coils that drive the CRT grids. I tried substituting an old style Miller replacement 120 mH peaking coil, but it shows the same white line.

Maybe I can track it down by putting in caps to filter out the noise at places along the video processing...