Tech-Master NIB TV Kit #5516 - Page 21 - Videokarma.org TV - Video

Crist Rigott · #**301** 01-07-2017, 12:36 PM

Quote:

Originally Posted by Kevin Kuehn

Boy that first picture is so close to being good. What happens if you slide the yoke back just a hair?

No help, but a good thought.

Kevin Kuehn · #**302** 01-07-2017, 01:23 PM

Quote:

Originally Posted by Crist Rigott

Just a note here. The sleeve seems to "compress" the whole picture, thus it fits into the viewing area of the CRT. It does not cutoff any portion of the picture.

I'll spend some time tweaking the picture to see what I can get without the sleeve and post the results here.

I did consider that maybe changing some cap might be an improvement.

But as someone pointed out you're actually under-scanning the screen in your second picture(the left edge of the picture is in view). Also the difference in width between the two picture seems to be about half of one square on each side, so it's not really a dramatic change in width. The idea behind over-scanning the screen was to make sure the edges of a 4:3 ratio picture never showed when the line voltage fluctuates.

Crist Rigott · #**303** 01-07-2017, 06:46 PM

Guys, I've just spent hours trying to adjust this TV with and without the sleeve. I just deleted the pictures by mistake that I wanted to post.

As of right now, I'm burned out on this thing.

Time to take some time off!!!!!

tom.j.fla · #**304** 01-07-2017, 07:02 PM

CRT televisions are all about the art of compramise. They are not like todays' digital sets. Do not beat your self up trying to get perfection. All any of us can do is get it as close as we can and leave it alone. All the best,Tom.J

Electronic M · #**305** 01-08-2017, 01:22 AM

Quote:

Originally Posted by tom.j.fla

CRT televisions are all about the art of compramise. They are not like todays' digital sets. Do not beat your self up trying to get perfection. All any of us can do is get it as close as we can and leave it alone. All the best,Tom.J

Truer words...

It is really easy to go off and fight windmills that are baked into the design when you want to optimize a tube set...Knowing when to declare good enough, or balance between two incurable issues that can not be fixed together is important to staying sane.

old_coot88 · #**306** 01-08-2017, 10:57 AM

I gotta concur with the last two postings. Any B&W tube TV, especially a low B+, minimalist design, is gonna have very fluid parameters in its performance, like tubes and components aging, low and/or fluctuating line voltage etc. The design has built-in 'headroom' to allow for this. And very few sets if any will display perfect linearity, either horiz or vertically. Even If you set everything as near 'perfect' as possible, it's gonna change on its own.

The results you've already attained with this project have knocked everybody's socks off, and achieved performance beyond any typical BW set of the period.

(Edit) There's an old adage relating to model aircraft design, but it applies here as well: "Perfectionism is the manic form of fuddyduddy-ism."

I would be 110% happy with what you have there now.

timmy · #**307** 01-10-2017, 03:46 PM

The pic in the other post without the sleeve to me and others look great and these old sets were far from perfect aside from today's sets, no comparison, but these old sets were not engineered to be perfect that's why there is 20% built in but today's sets may have 1 or 2% built in, that's it. I say leave it alone looks great without the sleeve, you hand built it , lot of work now just enjoy it. It took me a long time to realize that these old sets are not perfect with all my annoying questions to a lot of members but not I'm cured, lol.

kvflyer · #**308** 01-11-2017, 07:53 AM

Very true about trying to get things to look exactly like the schematic wave forms or voltages spot on.

Now if you really want to beat yourself up, do a purity and then convergence on an old round CRT color set, say from 1959 or so! I remember reading that you should concentrate on the center of the picture and the edges will be as good as they will be (read, not always perfect).

Good time for a coffee (or beer, depending on the time of day

)

dtvmcdonald · #**309** 01-11-2017, 10:37 AM

I don't know about 21AXP22 sets, but the 15GP22 CT-100 can indeed achieve truly perfect convergence, viewed at 3 feet. Mine showed that last night.

What's not easy, and perhaps impossible without at least one mod, is
keeping it near perfect at all average brightness levels (up to blooming of course.)

I got a great improvement by regulating the focus voltage (at the bottom end
of the focus pot only) with a big chain of Zeners and checking all the parts
including the pot in the 20kV regulator circuit and replacing ones
even a little off. It helps to be sure your
HV probe is calibrated right and setting the HV right at the top limit.

kvflyer · #**310** 01-11-2017, 04:51 PM

Quote:

Originally Posted by dtvmcdonald

I don't know about 21AXP22 sets, but the 15GP22 CT-100 can indeed achieve truly perfect convergence, viewed at 3 feet. Mine showed that last night. ...
HV probe is calibrated right and setting the HV right at the top limit.

Oh, I hate you and you had to rub that in!

Just kidding of course and glad that you have a CT-100 with a good 15GP22. I doubt that I will ever have one. But I do have a CTC-9 that is in queue and hope to get to it soon.

So, please do enjoy that CT-100. There are not many out there, let alone ones with a good CRT. I am sure you understand and appreciate that!

Crist Rigott · #**311** 01-14-2017, 08:29 PM

Thanks for all the good comments guys. It is appreciated.

Here is a video of what I'm dealing with. This is without the sleeve and using my OTA and converter.

https://youtu.be/uQW7s4tmZM0

Later on from that recording, I tried a 17LP4 CRT with pretty much the same over scan.

old_coot88 · #**312** 01-15-2017, 01:17 AM

Well, I gotta retract my earlier pontification.

It looks like you do have some excessive overscan. Startin' to sound like a broken record, but have you considered trying a bit of resistance in series with the H yoke winding? Dunno if it'll affect the HV as I've never tried it. But it might be worth a shot. Maybe 20 ohms to start out.

Electronic M · #**313** 01-15-2017, 10:51 AM

That is odd...Was the earlier test pattern somehow letter-boxed and pillar-boxed, or is the DTV box set to zoom?...There is a clear difference in apparent over-scan between the two signals you've shown.

Crist Rigott · #**314** 01-15-2017, 07:07 PM

Quote:

Originally Posted by old_coot88

Well, I gotta retract my earlier pontification.

It looks like you do have some excessive overscan. Startin' to sound like a broken record, but have you considered trying a bit of resistance in series with the H yoke winding? Dunno if it'll affect the HV as I've never tried it. But it might be worth a shot. Maybe 20 ohms to start out.

I'll try that. It'll be a week or so till I can get back to the TV.

Crist Rigott · #**315** 01-15-2017, 07:08 PM

Quote:

Originally Posted by Electronic M

That is odd...Was the earlier test pattern somehow letter-boxed and pillar-boxed, or is the DTV box set to zoom?...There is a clear difference in apparent over-scan between the two signals you've shown.

Tom,
Not sure what you mean by letter-boxed or pillar-boxed. The DTV does not have a zoom feature.

Maybe I can borrow another converter box.