Motorola roundie

[Electronic M]

Originally Posted by timmy

I guess you could say the afc attempts failed because I never had a problem like this so Grounding point G I would not have known what was right or wrong. So the coil may show 1-2 on sams but it was actually 3-4. At least I was able to figure that out lol.

When I look for test points (except for tube socket pins which are well standardized or well labeled PCB or chassis stakes) I always look for 2 components that connect to the test point and trace them to their common junction to make sure I'm not on the wrong end of a resistor/capacitor or wrong lug of a coil...It's good practice and it's saved me headaches a few times. I've also seen Sam's have schematic and or typographic details wrong several times so I like to make sure everything makes sense to me.

Sometimes ( especially on point to point sets) rushing ahead without a clear understanding of what you are interacting with can lead you to accidentally changing things in a way that breaks things and is hard to find.

[timmy]

Just yet another learning experience well as long as these sets are around.

[timmy]

Why is it some colors are alittle bit different from a flat tv to a crt tv

[Yamamaya42]

Originally Posted by timmy

Why is it some colors are alittle bit different from a flat tv to a crt tv

NTSC= Never Twice the Same Color.

[old_tv_nut]

Originally Posted by timmy

Why is it some colors are alittle bit different from a flat tv to a crt tv

Multiple reasons.

1) The picture tube primary colors (phosphors) were changed over time from the original NTSC standards to get brighter pictures (the green saw the largest changes, but blue changed significantly also. The red changed slightly; the strongest change was toward orange in the all-sulfide tubes.
2) TV manufacturers made proprietary changes to the color circuits to partially compensate for the phosphor changes
3) TVs for a long time used a quite cyan white balance, to reduce the load on the red electron gun, due to the relative inefficiency of red phospors
4) meanwhile, TV cameras were designed to make good pictures with the newer phosphors, so there were two rather uncontrolled adjustments in the system, at the camera and in the receiver.

5) Finally! PAL and HDTV settled on the correct circuitry in cameras and receivers for the new phosphors, which also became the sRGB standard for computer images (jpg files).

[timmy]

Originally Posted by old_tv_nut

Multiple reasons.

1) The picture tube primary colors (phosphors) were changed over time from the original NTSC standards to get brighter pictures (the green saw the largest changes, but blue changed significantly also. The red changed slightly; the strongest change was toward orange in the all-sulfide tubes.
2) TV manufacturers made proprietary changes to the color circuits to partially compensate for the phosphor changes
3) TVs for a long time used a quite cyan white balance, to reduce the load on the red electron gun, due to the relative inefficiency of red phospors
4) meanwhile, TV cameras were designed to make good pictures with the newer phosphors, so there were two rather uncontrolled adjustments in the system, at the camera and in the receiver.

5) Finally! PAL and HDTV settled on the correct circuitry in cameras and receivers for the new phosphors, which also became the sRGB standard for computer images (jpg files).

Interesting , lots of changes just for tv.

[Yamamaya42]

That, and you can't really compare the two, as they are vastly different techs. ( all joking about NTSC aside! :P )

With the vintage set, there will always be variations, no two CRTs are exactly alike, nor is any chassis, even if of the same make mo#, change a tube, and it will act slightly different.
And with NTSC, there is the infamous TINT control, https://en.wikipedia.org/wiki/Tint_control.
Always a source of fun to get JUST RIGHT!

But as things went over to flat/digital, these variations became almost, but not quite non existent between sets and other makes models of flat screen sets, a very keen discerning educated eye can still see differences, but to the average person, they look very much alike these days.

[timmy]

Originally Posted by Yamamaya42

That, and you can't really compare the two, as they are vastly different techs. ( all joking about NTSC aside! :P )

With the vintage set, there will always be variations, no two CRTs are exactly alike, nor is any chassis, even if of the same make mo#, change a tube, and it will act slightly different.
And with NTSC, there is the infamous TINT control, https://en.wikipedia.org/wiki/Tint_control.
Always a source of fun to get JUST RIGHT!

But as things went over to flat/digital, these variations became almost, but not quite non existent between sets and other makes models of flat screen sets, a very keen discerning educated eye can still see differences, but to the average person, they look very much alike these days.

Well I hate flat panel tvs the color even looks fake and to me it’s kind of hard on the eyes. And no more crt tvs is really a lot of crap them saying hazardous materials there is more crap burning diesel fuel and not everyone goes by the recycling program I think it was just a new technology they wanted to get out there.

[Yamamaya42]

For all practical purposes, CRTs were/are hazardous waste, they made millions of them, w/o any foresight to recycle them, so they get tossed out and end up in land fills, many of them have lead and other heavy metals, these are items of this type that went down this path, nor should they be condemned because of this, really.

[Electronic M]

It's been argued here before by others that lead is added to glass through vitrification and that nuclear waste is safely disposed of by vitrification into glass and that if the process is good enough for nuclear waste it should be fine for lead. As I understand it you won't really be getting much out of lead glass unless you grind it up and chemically break down the glass in something like acid.

Just repeating material from previous posters in topics I find interesting...

[old_tv_nut]

Originally Posted by timmy

Well I hate flat panel tvs the color even looks fake and to me it’s kind of hard on the eyes. And no more crt tvs is really a lot of crap them saying hazardous materials there is more crap burning diesel fuel and not everyone goes by the recycling program I think it was just a new technology they wanted to get out there.

Actually, modern flat screens have much better color than the old CRT sets, IF you turn off the "lighthouse" default sales-floor mode and set them to a calibrated mode. This is especially true because of the much better contrast (consistent, blacker blacks) of flat panel sets.
This was not true with the very early flat sets because makers had not gotten the hang of compensating the extreme non-linearity of LCDs to match the ideally smooth non-linearity of CRTs.

[dtvmcdonald]

Originally Posted by old_tv_nut

Actually, modern flat screens have much better color than the old CRT sets, IF you turn off the "lighthouse" default sales-floor mode and set them to a calibrated mode. This is especially true because of the much better contrast (consistent, blacker blacks) of flat panel sets.
This was not true with the very early flat sets because makers had not gotten the hang of compensating the extreme non-linearity of LCDs to match the ideally smooth non-linearity of CRTs.

I would not say that the color itself of the new flat screens is much better.
It is the basic light intensity curves, which are obvious in B&W. The perfection of gray scale if of course better too. That's because they are all adjustable ... but most people don't do it. And in many cases the default so-called "correct" setting is artificially far to dim (to match the default too-dim screens of movie theaters).

I can and have gotten my old Sony Bravia and my CT-100 to be essentially perfect matches by adjusting the Sony gamma to match that of the CT-100,
which is not ideal. IF you adjust the Sony to the correct gamma, you can get either mid-tone hues to match, or high-tone hues to match, but not both at once. This is with the Sony hues correct. I can do the same with my high-end Dell "Photoshop edit" monitor. This is with the one additional adjustment I added to my CT-100 color matrix, which gives complete control. The correct setting is within the standard resistor tolerances, but noticeably off the nominal value.

The difficult hues are in the yellow vs yellow-green and purple vs. violet areas.

[etype2]

I’ve posted this once prior, which is an excellent power point presentation by ISF (Imaging Science Foundation), and I think pertinent to the current discussion of this thread.

The industry moved to better calibration of consumer sets perhaps, the early 2000’s.

https://visions4netjournal.com/wp-co...-2017-33.3.pdf

[old_tv_nut]

Originally Posted by dtvmcdonald

...This is with the one additional adjustment I added to my CT-100 color matrix, which gives complete control...

What adjustment did you add?

[dtvmcdonald]

Originally Posted by old_tv_nut

What adjustment did you add?

I don't remember for sure. It was one of the six resistors from the I and Q
phase inverters to the three adders. I thought about which adjustment direction was missing. I thought again just now and come to the conclusion that it had to be one of the two resistors coming from the plate of the Q phase inverter.

Its no longer there. I had already replaced the six resistors with high stability
1% ones, and when I got the adjustments right I replaced the pot with
one of those fixed ones. As I said, it was within the stated 5% tolerance of those resistors.

If you look long enough at the list of adjustments, i.e. CRT screens, user color control, blue and green video gains, I gain, and relative demod phase, you come up with one degree of freedom too few for complete control.

As I have said innumerable times, this set has, for a single VHF channel,
81 adjustments. I adjusted every single one. The most critical are the two yoke tilts and two yoke lateral shift adjustments. Get these right and essentially perfect convergence is possible. Interestingly, when I replaced the CRT they did not need changing significantly ... the marks I had made were just fine.

Zenith's famous quip is wrong.