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  #1  
Old 04-13-2018, 04:08 PM
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The broadcast color stripe signal

Prizes related to this post:

3rd place: you remember reading about this test signal
2nd place: you remember seeing this signal on a black and white set
1st place: you remember using this signal to test a color set
Grand Prize: you worked for a station that implemented this signal.

The signal referred to is a pair of color bursts added to a black and white program inside the active picture area, on the extreme left and right. The idea was that, during a monochrome broadcast, a color set could be tested for basic function by turning the horizontal hold control to phase the horizontal so that the burst at the left of the screen was gated by the receiver burst gate, and therfore the color came on, and the right side burst was seen as a color stripe on the color set.

The signal could be seen as stripes of subcarrier dots in monochrome sets.

This was explained in the old SAMS Color TV Training Manual by Oliphant and Ray (no copyright date).

I recall looking at this on my family's monochrome set as a teenager when I was learning all I could about color TV, but I will leave the prize categories open for some others to claim.

By the way, this seems to be an indication of a possible problem with early sets, in that the horizontal could be misadjusted to place the burst gate during active video on color programs too!

Edit: I found a copy with the printing info: TVC-1, First Edition, First Printing, May 1956
Attached Files
File Type: pdf Color Stripe test signal.pdf (964.4 KB, 45 views)
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Last edited by old_tv_nut; 04-13-2018 at 04:17 PM.
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Old 04-13-2018, 10:04 PM
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I lose!
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Old 04-14-2018, 09:44 AM
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Engineers do some weird things when they don't have enough funds to do what they want.

The ability to detune the H till video reaches burst gate is worrisome it also may explain some sets tendency to drift color from station to station and or randomly. With overscan hiding edge rollover I can see this as being a common consumer misadjustment.
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Old 04-14-2018, 10:52 AM
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Rca wa-8

This color stripe generator was an accessory. Most likely only major market stations had them. Never saw one though. Attached is a write-up from a '56 copy of the NAB Handbook.
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File Type: jpg WA8-1.jpg (43.9 KB, 14 views)
File Type: jpg WA8-2.jpg (107.3 KB, 20 views)
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Old 04-14-2018, 11:23 AM
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Scroll down to page 27 of this pdf:
http://thehistoryofrecording.com/Lit...ision-1966.pdf
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Old 04-16-2018, 05:20 PM
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thanks for the references
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Old 04-26-2018, 09:49 PM
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I remember some stations broadcast a yellow vertical stripe on the left side of the screen when a black and white program was being aired. This was in the early 1960's. I was told it was so TV service persons could determine that the set was working properly even though no color programming was available. I wonder if this was the same thing?
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Old 04-26-2018, 09:54 PM
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Quote:
Originally Posted by Telecruiser View Post
I remember some stations broadcast a yellow vertical stripe on the left side of the screen when a black and white program was being aired. This was in the early 1960's. I was told it was so TV service persons could determine that the set was working properly even though no color programming was available. I wonder if this was the same thing?
Yes, the same thing, but usually it would not appear at the left side, but the right, as the one on the left would act as the color burst when the horizontal phase is slightly delayed. I think it is less likely that the phase could be pulled so far the other way, but maybe. I wish I had a source of this signal so I could try it on the CTC-5.
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Old 05-01-2018, 09:37 PM
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Quote:
Originally Posted by old_tv_nut View Post
Yes, the same thing, but usually it would not appear at the left side, but the right, as the one on the left would act as the color burst when the horizontal phase is slightly delayed. I think it is less likely that the phase could be pulled so far the other way, but maybe. I wish I had a source of this signal so I could try it on the CTC-5.
Maybe it was on the right side. My memory seems to not be quite as good as it used to be. It was over 50 years ago when I last saw this. I worked part time at a TV shop while in high school. We used the test signal quite frequently to see if the set was actually working. Otherwise we had to hang around until Bozo came on, which was in color.
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Old 05-02-2018, 02:22 PM
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I did an experiment. I have a DTV converter that includes playback of multimedia from a USB port, so I created an Indianhead test pattern jpg with two blue stripes in Photoshop.

The reason for making the stripes blue is that the media player always has its color burst on, so if phasing the horizontal hold over to the stripe works, the stripe color should change from blue to yellow-green. As you can see it works (at the extreme of the hor hold setting just before it loses sync)!

This is not an exact reproduction for a couple of reasons:
1) the only way I could produce the stripes in Photoshop affected the luminance as well as the chroma, that is, the stripes are actually darker than the background.
2) I don't know exactly what scale factors the media player uses to translate the jpg resolution to the NTSC output. The jpg is 720 pixels wide, but maybe it would work better with 640 or something else.
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Old 05-03-2018, 09:39 PM
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I think I had read about the stripe in an older copy of the "RCA Color TV Pict-O-Guide". I figured it was one of those little things that were long ago lost to history!
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Old 05-04-2018, 03:23 PM
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That color stripe was essential in color's early days, to set the fine tuning during the day so that the one or two color programs that evening would be in color. Worked really well.
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Old 05-15-2018, 10:13 PM
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The Admiral service manual supplement for the first Admiral 21 inch color set says it had a test point that would shift the phase of the horizontal for use with the stripe:

COLOR STRIPE TEST
A test point is provided on the rear apron of the chassis to test for color reception in those areas where color stripes are transmitted during black and white transrnission, see Figure 27.
To make color stripe test, proceed as follows:
a. Tune in station transrnitting black and white picture with color stripes.
b. Short test point to chassis ground with clip lead or screwdriver (picture will shift toward the left and perrnit easy viewing of stripe on the right side).
c, If necessary, readjust Fine Tuning control, with Color Intensity control set to near maximum.
Stripe should appear in color. If not, receiver is not reproducing color.
d. To check color intensity, vary Color Intensity control from minimurn to maximum, At maximum, color of stripe should appear vivid and at minimum, no color at all.
e. To check color fidelity, vary Color Fidelity control throughout its range. At some setting,
stripe should appear yellowish-green; if not, receiver will not reproduce correct colors.
f. If color stripe appears to contain colored bars, which repeatedly keep changing color (similar to
barber pole), receiver is not in "Color Sync." See Color Sync Alignment in Service Manual No. s592.
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Last edited by old_tv_nut; 05-15-2018 at 10:21 PM.
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