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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 2:24 pm 



Joined: 07 Aug 2018
Posts: 66
Uhh, that is some nice work! Very interesting stuff. I'm right in the process of moving and I'm gonna have all my monitors with me in my new big basement. I'm gonna start experimenting hopefully soon and will see if I can incorparate that design. Having a potentiometer is so much nicer.

Where did you find a potentiometer for that voltage?


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 4:08 pm 


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Joined: 09 Aug 2017
Posts: 1529
Location: Australia
Can you post 2 side by side pictures of 0v and -229v but set the brightness level on -229 to match -0v?

I'm interested to see if there is a difference at all.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 4:15 pm 



Joined: 17 Aug 2020
Posts: 120
ElBartoME wrote:
Uhh, that is some nice work! Very interesting stuff. I'm right in the process of moving and I'm gonna have all my monitors with me in my new big basement. I'm gonna start experimenting hopefully soon and will see if I can incorparate that design. Having a potentiometer is so much nicer.

Where did you find a potentiometer for that voltage?


The pot is rated for up to 250V and 250mW, which is more than enough for this application. I bought it from here. The snap-in knobs for the pot are optional, and come in a variety of designs. If you don't use a snap-in knob, you can just use a plastic alignment tool or screw driver to adjust the pot. I went for the very long dial here so that it could be safely adjusted by hand without a tool.

I also put together a "simple" version of this design, without the pot and ripple filtering. The filtering is overkill, and the pot is unnecessary if you are going to stick with a single setting. As you can see, this simple version is very easy to build, and it does not require adding a new winding to the flyback:
Image

"Flyback-pin" can just be a wire that is soldered to one of the pins on the flyback that has a waveform with a peak to peak voltage of somewhere between 150 and 250 volts peak to peak. R1 limits the current used, especially during powering on. C1 and D1 together create the "new" power supply. C1 is a coupler that provides galvanic isolation and removes the DC bias of the input power, while D1 makes the "new" power supply a negative rail. D2 converts the AC to DC, and C3 removes the noise and smooths the output.

Here is another side-by-side, but since it was taken during the day, the bright sunlight added glare and washed out the colors, especially the blacks.
Image


Last edited by LukeEvansSimon on Mon May 03, 2021 10:07 pm, edited 2 times in total.

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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 4:19 pm 



Joined: 17 Aug 2020
Posts: 120
Syntax wrote:
Can you post 2 side by side pictures of 0v and -229v but set the brightness level on -229 to match -0v?

I'm interested to see if there is a difference at all.


The brightness levels are matched. I used 240p Test Suite's color bars pattern to match the black levels and white levels of both. The decreased light output of the picture on the right is because less phosphor surface area is being illuminated. But you sound like a CRT tech expert, so please enlighten us all on your infinite wisdom as to why you think the brightness levels are not matched.

I'm interested to see if you know anything at all.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 5:21 pm 


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Joined: 09 Aug 2017
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Location: Australia
Funny, doesn't look so bright compared to 0v.

Seems like a really involved method of turning the screen brightness down.

That and a waste of time. The 480p thing sounds much more interesting.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 5:25 pm 


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Joined: 16 Jan 2014
Posts: 1376
Oh snap! :lol:


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 5:31 pm 



Joined: 06 Mar 2021
Posts: 27
Great work (OP and others). Making a consumer SD set is certainly interesting, but what about making an HD CRT multi sync? It inherently has the video bandwidth, you just have to allow sync rates other than 35kHz to get to the tube, right? The reason I ask is because the 34XBR960 had a display pass through that allows 1080i to propagate through with no lag. If you could hardwire the muxes to always pass through the input signal, theoretically you could make it multi sync, right? Over driving to get it to 720p or even 1080p would be amazing, too.

I’m willing to guinea pig my set for the cause. Would love to mod my 27FV300 too, though I wonder how far back you’d need to modify to support 31khz sync or greater through all the datapaths.

Also, I get that this mod rejuvenates the cathode, but will decreased spot size contribute to acceleration of phosphor aging?


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 5:59 pm 



Joined: 17 Aug 2020
Posts: 120
Syntax wrote:
Funny, doesn't look so bright compared to 0v.

Seems like a really involved method of turning the screen brightness down.

That and a waste of time. The 480p thing sounds much more interesting.


Thanks for your scientific analysis about "look so bright" and "turning the screen brightness down". The technical details you have provided are a tremendous gift to the CRT gaming community :lol: Honestly though, you clearly have little understanding about the science behind how CRTs work.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 7:17 pm 


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Location: bmore
LukeEvansSimon wrote:
Here is another side-by-side, but since it was taking during the day, the bright sunlight added glare and washed out the colors, especially the blacks.
Spoiler: show
Image


Even if we have science on paper, the presented result is ultimately an observational one.

If your optimized example looks super dark in comparison to your baseline, it doesn't effectively show the advantage in your technique versus turning down the picture controls to reduce blooming. If the two photos were taken in the same lighting conditions, what does that suggest about the difference in brightness (or not) between the two example photos?

It would really behoove you to have a couple of well take photos of a system paused on a specific screen, with the camera on a tripod and fixed in place on a locked focus and exposure setting, in a dark room.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 7:54 pm 



Joined: 07 Aug 2018
Posts: 66
LukeEvansSimon wrote:
I also put together a "simple" version of this design, without the pot and ripple filtering. The filtering is overkill, and the pot is unnecessary if you are going to stick with a single setting. As you can see, this simple version is very easy to build, and it does not require adding a new winding to the flyback


That is awesome. I'm gonna build this type of supply the next time I get the chance, although I still suggest putting in the potentiometer. That makes my life so much easier. I hated playing around with the number of turns of the winding.

That makes it also possible to change the spot size "on the fly" more or less.

vol.2 wrote:
It would really behoove you to have a couple of well take photos of a system paused on a specific screen, with the camera on a tripod and fixed in place on a locked focus and exposure setting, in a dark room.


I like that idea. When I have my "lab" set-up I will use a tripod to make pictures with different with the lights off at night. Most of the Sony consumers I modded keep the brightness constant when I change G1 and G2. But I'm still gonna verify the brightness.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 8:07 pm 



Joined: 17 Aug 2020
Posts: 120
vol.2 wrote:
LukeEvansSimon wrote:
Here is another side-by-side, but since it was taking during the day, the bright sunlight added glare and washed out the colors, especially the blacks.
Spoiler: show
Image


Even if we have science on paper, the presented result is ultimately an observational one.

If your optimized example looks super dark in comparison to your baseline, it doesn't effectively show the advantage in your technique versus turning down the picture controls to reduce blooming. If the two photos were taken in the same lighting conditions, what does that suggest about the difference in brightness (or not) between the two example photos?

It would really behoove you to have a couple of well take photos of a system paused on a specific screen, with the camera on a tripod and fixed in place on a locked focus and exposure setting, in a dark room.


For CRTs, "brightness" refers to black level calibration, which is only one component of 3 determining factors for total light emission from a CRT. White level calibration and spot size are the other two determining factors. If all you did was turn brightness down, you'd crush all of your shades of grey into black, and all dark shades of green, blue, and red (as well as all variations of them), would be crushed into black.

To understand why "brightness" is the wrong term, consider a pixel pattern that is a single dark red pixel on an entirely black background. Turning the brightness down would make the pixel disappear (crush into black). This mod does something different, it decreases the size of the area of phosphor that is illuminated when drawing the pixel, but the illuminated area is still the same dark shade of red and it is still visible. It is true that the photon flux density for the CRT screen's face is reduced by this mod, and the photon flux density is also reduced by turning the brightness down. But they are two different things that alter the picture in two different ways.

People often misunderstand the difference between black levels (brightness), white levels (contrast), and photon flux density (total light emission).


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 9:10 pm 


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Joined: 05 Mar 2018
Posts: 1552
LukeEvansSimon wrote:
vol.2 wrote:
LukeEvansSimon wrote:
Here is another side-by-side, but since it was taking during the day, the bright sunlight added glare and washed out the colors, especially the blacks.
Spoiler: show
Image


Even if we have science on paper, the presented result is ultimately an observational one.

If your optimized example looks super dark in comparison to your baseline, it doesn't effectively show the advantage in your technique versus turning down the picture controls to reduce blooming. If the two photos were taken in the same lighting conditions, what does that suggest about the difference in brightness (or not) between the two example photos?

It would really behoove you to have a couple of well take photos of a system paused on a specific screen, with the camera on a tripod and fixed in place on a locked focus and exposure setting, in a dark room.


For CRTs, "brightness" refers to black level calibration, which is only one component of 3 determining factors for total light emission from a CRT. White level calibration and spot size are the other two determining factors. If all you did was turn brightness down, you'd crush all of your shades of grey into black, and all dark shades of green, blue, and red (as well as all variations of them), would be crushed into black.

To understand why "brightness" is the wrong term, consider a pixel pattern that is a single dark red pixel on an entirely black background. Turning the brightness down would make the pixel disappear (crush into black). This mod does something different, it decreases the size of the area of phosphor that is illuminated when drawing the pixel, but the illuminated area is still the same dark shade of red and it is still visible. It is true that the photon flux density for the CRT screen's face is reduced by this mod, and the photon flux density is also reduced by turning the brightness down. But they are two different things that alter the picture in two different ways.

People often misunderstand the difference between black levels (brightness), white levels (contrast), and photon flux density (total light emission).

The bottom line is regardless of the correct terminology nobody cares if it looks darker they will say it's darker. Instead of getting mired in the wording you should respond to his actual point


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 9:39 pm 



Joined: 17 Aug 2020
Posts: 120
maxtherabbit wrote:
The bottom line is regardless of the correct terminology nobody cares if it looks darker they will say it's darker. Instead of getting mired in the wording you should respond to his actual point


I am pretty sure I have responded, multiple times, to the following incredibly insightful statements: (1) this is the same as turning down the brightness, and (2) this is the same as tuning the focus pot on the flyback.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 10:07 pm 


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LukeEvansSimon wrote:
maxtherabbit wrote:
The bottom line is regardless of the correct terminology nobody cares if it looks darker they will say it's darker. Instead of getting mired in the wording you should respond to his actual point


I am pretty sure I have responded, multiple times, to the following incredibly insightful statements: (1) this is the same as turning down the brightness, and (2) this is the same as tuning the focus pot on the flyback.


How about, instead of posting cocky replies to legitimate queries, actually responding to the points made? All the science in the world is not going to help you if the end result is ultimately not worth the hassle.

Actually turn down brightness and show us that it's not the same. Make a video in a dark room using a tripod, mention which camera you're using and the settings. Slowly turn the pot towards -229V starting from the 0V initial position. Can't be that hard.

Also it's still unproven that you're increasing TVL. Do the honorable thing, change the title.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 10:10 pm 



Joined: 17 Aug 2020
Posts: 120
Blacksheep wrote:
How about, instead of posting cocky replies to legitimate queries, actually responding to the points made?


I have responded several times to several different people that pop into this thread and claim "this is the same as turning the brightness down" or "this is the same as changing the focus pot". So whenever somebody pops into this thread and adds their cocky reply along one of those two statements, they will get a cocky reply back.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Mon May 03, 2021 10:57 pm 


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LukeEvansSimon wrote:
So whenever somebody pops into this thread and adds their cocky reply along one of those two statements, they will get a cocky reply back.



That didn't happen. I brought up a flaw (that you qualified in your own post by saying your room was too bright) in your photographic comparison and suggested a way to address it. I never made either one of those statements.

I was hoping to help you bring a more positive environment to you thread and to dispel some of the trolling and negativity, not to argue with you about the merits of your project.

I wish you all the best.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Tue May 04, 2021 8:03 am 


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Joined: 09 May 2005
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Come on everybody, please don't get personal. This is a fascinating topic and I'd hate to see the discussion get thrown out because we have disagreements on minor details.

Whether or not the original mod was successful in increasing a TV's TVL rating, it seems like the OP and others are trying to make progress in that direction through other means and IMO the thread title is still appropriate.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Tue May 04, 2021 9:24 am 



Joined: 17 Mar 2018
Posts: 171
Location: Germany
vol.2 I don't think he was addressing your post, but rather Syntax's.

And I agree, I really hope the constant naysayers don't push Luke to completely abandoning the project or at least stop posting his findings here. That would be a shame.


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Tue May 04, 2021 12:04 pm 



Joined: 07 Aug 2018
Posts: 66
vol.2 wrote:
That didn't happen. I brought up a flaw (that you qualified in your own post by saying your room was too bright) in your photographic comparison and suggested a way to address it. I never made either one of those statements.


That is constructive criticism the way I like it. You made a valid point and gave a suggestion how to fix it.


But the pages and pages of (sometimes in my opinion pointless) discussions made me also tired to work on this topic or share my results.
Everytime the thread dies down and Luke comes back with some new findings there is new drama. :roll:


I made this picture some time ago in a dark room. Without a tripod though. They both should be at the same brightness, but next time I'm gonna make some pictures with a tripod and make sure the brightness is constant.

https://i.imgur.com/zTnWvFC.jpg


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Tue May 04, 2021 2:08 pm 


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I will say, even if this mod is not for me (I prefer softer RGB picture),

it did teach me something (spot size) and I'm thankful for that

and I hope it'll keep going because even if it doesn't interest me, it might interest other people
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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Wed May 05, 2021 4:11 am 



Joined: 13 Jun 2020
Posts: 2
Thanks for all your hard work Luke.

I am interested in trying this on a KV-20S10. I would like to add a switch to make it easier to take before/after photos.

Would something like this work?

Image


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 Post subject: Re: Mod a CRT to increase its TVL
PostPosted: Thu May 27, 2021 6:40 am 


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Location: ME, USA
Just wanted to say I appreciate the work you’ve put into this, and I enjoy reading all of the technical information written, even though a lot of it is over my head. I hope that your findings will one day be able to unlock the potential of my D-series to become a 36” multisync monitor. Not that I have the skills to do it myself :roll:

Looking forward to seeing more pics as well!


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