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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Wed Sep 23, 2020 7:40 pm 



Joined: 07 Apr 2016
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The development and information surrounding this mod is really interesting and promising. I look forward to any and all updates. Awesome job! :D


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Wed Sep 23, 2020 8:21 pm 


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"the ability to alternative more vertical white and black lines" IS a sharper image lol


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Wed Sep 23, 2020 9:05 pm 


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LukeEvansSimon wrote:
TVL is also a stupid metric that was clearly designed for marketing purposes as opposed to properly informing people about a display's properties.

So why is that metric rarely mentioned in the specs of consumer TVs, but almost always specified in the specs of professional/broadcast monitors?
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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Wed Sep 23, 2020 9:12 pm 


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Quote:
CRTs are analog video devices, so mask dot pitch is one of 3 factors that can bottleneck resolvable TVL.


Removing a bottleneck in a process does not inherently result in greater production in the process. I just counted the vertical lines in the two images in a given space and they are still the same. TVL has not increased. Perhaps what you are doing might make it possible to increase TVL if the other two factors are also modified, but alone, it does not.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Wed Sep 23, 2020 10:01 pm 



Joined: 17 Aug 2020
Posts: 81
Unseen wrote:
LukeEvansSimon wrote:
TVL is also a stupid metric that was clearly designed for marketing purposes as opposed to properly informing people about a display's properties.

So why is that metric rarely mentioned in the specs of consumer TVs, but almost always specified in the specs of professional/broadcast monitors?


It was a useful marketing metric for selling to businesses and professionals who are not immune from bad marketing metrics.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Wed Sep 23, 2020 10:15 pm 



Joined: 17 Aug 2020
Posts: 81
Josh128 wrote:
Quote:
CRTs are analog video devices, so mask dot pitch is one of 3 factors that can bottleneck resolvable TVL.


Removing a bottleneck in a process does not inherently result in greater production in the process. I just counted the vertical lines in the two images in a given space and they are still the same. TVL has not increased. Perhaps what you are doing might make it possible to increase TVL if the other two factors are also modified, but alone, it does not.


You are confusing "addressable" resolution versus "resolvable" resolution. As I stated in the original post, this mod increases the resolvable resolution, NOT the addressable resolution. Also, the maximum addressable resolution that the SNES and PS2 can output is 480 TVL. The same applies to all of the old 15khz analog video games. A higher TVL CRT cannot magically increase the addressable resolution of these game systems. A higher TVL CRT makes the blank scan lines thicker and the illuminated scan lines thinner. It also makes the image more sharp. This is exactly what this mod accomplishes.

Also, what you said also applies to all of the high TVL PVMs and BVMs. The best a SNES or PS2 can display on those high TVL CRTs is 480 TVL. A 600 TVL PVM does not make a SNES or PS2's addressable TVL 600. For digital video displays such as LCDs, the maximum addressable resolution and the maximum resolvable resolution are the same thing. I think this is what trips up most people, as they have been living with digital displays for so long, they use their intuition for digital displays to reason about analog CRTs where addressable and resolvable resolution are two very different things.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Wed Sep 23, 2020 11:05 pm 


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Josh128 wrote:
Quote:
CRTs are analog video devices, so mask dot pitch is one of 3 factors that can bottleneck resolvable TVL.


Removing a bottleneck in a process does not inherently result in greater production in the process. I just counted the vertical lines in the two images in a given space and they are still the same. TVL has not increased. Perhaps what you are doing might make it possible to increase TVL if the other two factors are also modified, but alone, it does not.


Ok, so TVL is a measure solely of how many black/white vertical stripes can be pictured visibly on a set (tube+chassis). If you reduce the spot size, this means you'll be able to resolve more lines cleanly (assuming for the moment that the dot-pitch is not noticeably larger than original spot size, which would prevent much improvement). This doesn't mean, however, that any given image will have more lines in it - that part has nothing to do with TVL. That's what Luke somewhat confusingly keeps referring to as addressability, and it just means how many pixels there are in the image being sent to the screen. To increase that you need to start playing with the number of horizontal pixels in your modeline so you can show more stripes. Super resolutions would be one example, or just something like the MiSTer can do this pretty easily. As an example of this, I'm running a consumer tube + chassis in an Arcade cabinet, at 800x600@50i for some newer games, and the image is much clearer than 480i, though the motion isn't as smooth.

Even before doing that, this mod certainly makes the image you're looking at a bit crisper and the scanlines and pixels more distinct. Which itself may help in increasing TVL, just not if you photograph the image and pore over it. As with pro-monitors, not every is looking for a sharper image, but I certainly am in most cases. The potential for increased x-ray production still needs to be tested however, at this stage.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Wed Sep 23, 2020 11:48 pm 


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The issue is not the horizontal addressability of the PS/PS2 or SNES. The issue is the granularity of the horizontal lines displayed by the TV. If you only display a single solid color line, on an inherently low TVL set like you are testing with, you will have visible black/spacing in between horizontal pixels of the same color, whereas if you display the same line on a set with higher TVL, those black lines become smaller and eventually disappear the higher you go. What ultimately limits you here is the shadow/slot mask or aperture grille. Unless the set was designed with a mask pitch that was not matched correctly to the sets spot size (ie much finer grille/mask spacing than spot size), decreasing the spot size alone will not give you higher TVL.

The horizontal granularity shown in your pics is limited to what it is by the mask, and unless Im missing something, theres no way around that without going to a finer pitched mask. These pictures below are from monitors using a pentile matrix style mask matrix, so you never really see the vertical black lines, but you can see the granularity differences and if it was an aperture grille or a slot mask, you would.


900TVL
Image


700TVL
Image


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 12:25 am 



Joined: 17 Aug 2020
Posts: 81
Josh128 wrote:
The issue is not the horizontal addressability of the PS/PS2 or SNES. The issue is the granularity of the horizontal lines displayed by the TV. If you only display a single solid color line, on an inherently low TVL set like you are testing with, you will have visible black in between horizontal pixels of the same color, whereas if you display the same line on a set with higher TVL, those black lines become smaller and eventually disappear the higher you go. What ultimately limits you here is the shadow/slot mask or aperture grille. Unless the set was designed with a mask pitch that was not matched correctly to the sets spot size (ie much finer grille/mask spacing than spot size), decreasing the spot size alone will not give you higher TVL.

The horizontal granularity shown in your pics is limited to what it is by the mask, and unless Im missing something, theres no way around that without going to a finer pitched mask. These pictures below are from monitors using a pentile matrix style mask matrix, so you never really see the vertical black lines, but you can see the granularity differences and if it was an aperture grille or a slot mask, you would.


Now you are changing your claim from addressable resolution not being increased (never was my claim) to stating that this mod does not decrease the dot pitch of the mask. I never claimed that this mod changes the visibility of the mask, which is a different attribute of a CRT than TVL. These are not digital displays. TVL and mask dot pitch are two different things. If the smallest spot that the CRT can draw, illuminates 2 slots in the mask before the mod and it illuminates 1 slot after the mod, then the resolvable TVL is 2x higher as it is now possible to illuminate every other slot. Yes, you can't address each slot because the resolution that the game systems can output is not that high.

I do agree that a lower mask dot pitch does result in a less visible mask, but that is not limiting the number of alternating vertical white and black lines that the CRT can draw... up until the spot size is as small as 1 slot. As I have stated multiple times, most consumer CRTs have a spot size of 2 slots! Professional CRTs have an even larger spot size to dot pitch, but largely because the dot pitch is much lower on professional CRTs. The mask dot pitch is not the limiting factor for most CRT's resolvable TVL.

I have a Panasonic BT-H1350Y and a Panasonic BT-H1390Y. Both are 750 TVL, but the Panasonic BT-H1390Y has a smaller mask dot pitch, so the mask is less visible, even though TVL is the same. The fact that the dot pitch is larger (worse) on the BT-H1350Y, even though the TVL is not lower is a real life example of how mask dot pitch is not the bottleneck for TVL. Both of these CRTs are the exact same 13-inch dimension CRT, both have 750 TVL, and yet one of them has a worse dot pitch. Is Panasonic lying about the TVL of these two CRTs, or is mask dot pitch and TVL two different metrics?

Finally, when sitting on a couch playing a 27-inch CRT TV, the mask is not visible, but the smaller spot size does make the picture more crisp looking and it makes the blank scanlines more prominent. We are talking about modding very large consumer grade CRTs. You don't sit at a desk to play games on them like you would a PVM. You lay back on a couch or bed.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 1:13 am 



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LukeEvansSimon wrote:
We are talking about modding very large consumer grade CRTs. You don't sit at a desk to play games on them like you would a PVM. You lay back on a couch or bed.

Would this benefit a 20" 4:3 Aperture Grille consumer CRT TV?


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 1:55 am 



Joined: 25 Nov 2019
Posts: 35
Wow, this is a really crazy mod. Thanks for sharing this!

Just to be clear, I will be unable to use this properly if my TV doesn't allow me to adjust the cutoff and gain on all three R,G, and B guns, right? I wonder if this can be done on arcade monitors?


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 4:30 am 



Joined: 17 Aug 2020
Posts: 81
GeneraLight wrote:
LukeEvansSimon wrote:
We are talking about modding very large consumer grade CRTs. You don't sit at a desk to play games on them like you would a PVM. You lay back on a couch or bed.

Would this benefit a 20" 4:3 Aperture Grille consumer CRT TV?


It will depend on the spot size to dot aperture pitch ratio. Smaller consumer CRTs tend to have a lower spot size per aperture/slot/dot pitch ratio than the larger consumer CRTs.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 4:38 am 



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rememberizer wrote:
Wow, this is a really crazy mod. Thanks for sharing this!

Just to be clear, I will be unable to use this properly if my TV doesn't allow me to adjust the cutoff and gain on all three R,G, and B guns, right? I wonder if this can be done on arcade monitors?


It depends on the electron gun design and the manufacturing quality. In other words, it may not be an issue. You will just need to try it out. Arcade monitors typically have potentiometers for tuning cutoff and gain for the RGB amps, so it will definitely work for arcade CRTs.

I have not seen a consumer CRT that doesn’t have any means of tuning gain and cutoff. It is either buried in a service menu or a pot somewhere. Sometimes it is even undocumented in the service menu. In the worst case you could switch out the fixed resistors on the NPN transistor RGB drive amps on the neckboard, for tuning gain, and bias (aka cutoff).

The RGB drive amp circuit on CRT neckboards is very straightforward NPN transistor amplifier design, where a few resistors are used to set the bias and gain. The only special thing is the amps are high voltage and high bandwidth.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 7:30 am 



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Josh128 wrote:
What ultimately limits you here is the shadow/slot mask or aperture grille. Unless the set was designed with a mask pitch that was not matched correctly to the sets spot size (ie much finer grille/mask spacing than spot size)


I think that this is one, but not the only factor. An example for this is that PVM 20M4E, L4, BVM 20F1E and E1E all use the same tube type, but are rated at 800, 800, 900 and 1000 TV lines respectively.
Although in case of the BVMs that could again be a marketing ploy, as the F1E and E1E don't have different service manuals... it would be interesting to directly compare their guts.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 1:15 pm 



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LukeEvansSimon wrote:

It depends on the electron gun design and the manufacturing quality. In other words, it may not be an issue. You will just need to try it out. Arcade monitors typically have potentiometers for tuning cutoff and gain for the RGB amps, so it will definitely work for arcade CRTs.


I have not seen a consumer CRT that doesn’t have any means of tuning gain and cutoff. It is either buried in a service menu or a pot somewhere. Sometimes it is even undocumented in the service menu. In the worst case you could switch out the fixed resistors on the NPN transistor RGB drive amps on the neckboard, for tuning gain, and bias (aka cutoff).

The RGB drive amp circuit on CRT neckboards is very straightforward NPN transistor amplifier design, where a few resistors are used to set the bias and gain. The only special thing is the amps are high voltage and high bandwidth.


I have one TV that doesn't have R cutoff in the service menu, only G and B. I suppose that could complicate things?


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 4:34 pm 


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Lots of confusion in this thread about TV Lines.

The term TVL, as it is (was) used in the industry, is for horizontal resolution.
It’s a function of the phosphor pitch of the aperture grill/shadow mask/etc.
Since there’s a finite number of vertical slits in an amputate grill, the resolvable horizontal resolution is finite.

For an analogue signal, the addressable horizontal resolution is infinite.

The addressable vertical resolution has no physical limit.
It’s only limited by the horizontal scanning frequency of the set.
The scanning frequency defines the number of vertical lines drawn per vertical refresh.
For 15kHz @ 60Hz it’s about 263 (~240 viewable), for 31kHz @ 60Hz it’s about 525 (~480 viewable).

So TVL is perpendicular to the number of lines scanned (aka 240p/480p/etc).


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 4:54 pm 



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I'm bookmarking this for the moment we don't need a huge high voltage transformer sitting next to the tv.
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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 5:11 pm 



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Posts: 81
Downcry wrote:
Lots of confusion in this thread about TV Lines.

The term TVL, as it is (was) used in the industry, is for horizontal resolution.
It’s a function of the phosphor pitch of the aperture grill/shadow mask/etc.
Since there’s a finite number of vertical slits in an amputate grill, the resolvable horizontal resolution is finite.

For an analogue signal, the addressable horizontal resolution is infinite.

The addressable vertical resolution has no physical limit.
It’s only limited by the horizontal scanning frequency of the set.
The scanning frequency defines the number of vertical lines drawn per vertical refresh.
For 15kHz @ 60Hz it’s about 263 (~240 viewable), for 31kHz @ 60Hz it’s about 525 (~480 viewable).

So TVL is perpendicular to the number of lines scanned (aka 240p/480p/etc).


I think another source of confusion is that people are confusing "spot size" with mask/grill "dot pitch". For CRT technology, "spot size" is a very specific term. It refers to the width of the spot the electron beam makes when it hits the screen. Electron beam spot size is typically at least 2 phosphor dots wide, if not more.

Yes, TVL measures horizontal resolution, and TVL is finite, as white and black spots on an illuminated scan line can only be alternated at most every other dot/slot/aperture. However, most CRTs have a spot size that is at least 2 dots/slots/apertures in width, so if a horizontal scanned line has 1000 apertures in the mask/grill, then the maximum number of alternating white and black dots is limited to 500. However, if the spot size is reduced to take up one aperture, then the number of alternating white and black dots is then higher, now limited to 1000. This is a 2x increase in resolvable TVL!

Vertical resolution is also finite, but not limited by the mask/grill. People fixate too much on the mask/grill's dot pitch, as that is analogous to LCD pixels, but these are analog devices. The phosphors are not pixels. The electron beam's spot size and horizontal deflection are the biggest determining factor for CRT vertical resolution and the spot size size can only be made so small by increasing the voltage differentials between cathode-G1 and G2-G1. Once those voltage differentials reach what is known as the cathode to G1 breakdown voltage or the G2 to G1 breakdown voltage, electrical arcing occurs between the cathodes and anodes. I have acquired a spec sheet for one of the tubes that I own and it actually lists these breakdown voltages. It is sad that these spec sheets are so difficult to find. They have very useful information in them. Electrical arcing causes the voltage differentials to drop, increasing spot size. I don't have specs for any aperture grill tubes, but I expect you could 4x vertical resolution by decreasing spot size, before you hit the breakdown voltage limit. Of course, there is also the limitation placed by horizontal deflection's limited scanning frequency. Aperture grill tubes have the additional benefit that the phosphor is continuous vertically, so the grill does not in any way limit vertical resolution.

CRTs that are designed to have a very small spot size with lower cathode-G1 and G2-G1 differentials, achieve this smaller spot size by having a much smaller physical gap between the cathode and G1 and the space between the G2 and G1. They also have a much smaller aperture at the end of the G1 anode. The reduced gaps between these components makes the electromagnetic fields between them stronger, but it also means that the breakdown voltages are also lower, so again, a physical limit occurs on vertical resolution because spot size can only be made so small.

Research and development in how to control the electron beam spot size was very extensively investigated 20 years ago, when CRTs started getting pushed to their limits due to the PC/internet revolution. The docs I linked in the original post come from that research and development.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 5:34 pm 



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fandangos wrote:
I'm bookmarking this for the moment we don't need a huge high voltage transformer sitting next to the tv.


Lab bench power supplies are used for rapid prototyping. An inexpensive version of this mod is possible as described by viletim, earlier in this thread. CRT flybacks have an exposed core. If you loop a wire around that exposed core about 125 times, then the voltage between the ends of the wire will be 250 volts. The current is extremely low, but that is a good thing because the G1 does not need a high current.

The trick that viletim described, of using a wire wrapped around the exposed core was an old school trick for increasing the CRT's heater voltage when the CRT gets very old and worn. Just loop a wire around the exposed core 4 times and the ends of the wire have a voltage of 8 volts. Increasing heater voltage from 6.3v to 8v allows for making an old dim, blurry CRT new again. This trick can be tried over and over again as the CRT ages, until a heater voltage of about 11v to 12v, when the heater filament will burn out. You'd need to hit more than 100,000 hours though before a heater voltage of 11v is required to get peak brightness and contrast.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 7:53 pm 



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What kind of wire?

Enameled wires will do?
Either way, for this mod, a good bunch of pictures or schematics would be the best. Similar to the rgb mod for sony models.
Tons of pics and schematics makes it easier to not burn anything.
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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 8:48 pm 


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I think the confusion surrounding the description of the mod as making it "high TVL" might be alleviated a bit if it's phrased more specifically "decreasing spot size to increase TVL such that the pitch of the tube becomes the limiting factor".

I would be interested in replicating your results using some common arcade monitors. If the results are as sharp as you describe, then I expect they can not really be well conveyed in photographs, so seeing it in person would be the best way to judge it.

As mentioned, seeing as the control grid supply should be relatively low current (ideally close to 0A, right?) wrapping another winding and smoothing with a high voltage capacitor sounds like a decent way to produce the needed voltage. Or, if nothing else, an additional transformer could be used.
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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 8:49 pm 



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fandangos wrote:
What kind of wire?

Enameled wires will do?
Either way, for this mod, a good bunch of pictures or schematics would be the best. Similar to the rgb mod for sony models.
Tons of pics and schematics makes it easier to not burn anything.


About 50 cents worth of 28 AWG enameled wire aka "magnet wire" will work best for looping around the exposed flyback core. A 50 cent rectifier diode and 50 cent 1uF film capacitor are also needed to ensure the 250 volt rail is smooth. These 3 parts make what is essentially an ultra basic, low current, high voltage DC power supply. Every CRT has a heartbeat that is generated by the horizontal deflection circuit. This heartbeat is what pumps the flyback with power, and by winding a wire around the exposed core of the flyback, some of that power is used to induce a high voltage in the wire. The rectifier diode (50 cent part) is used to convert the current to DC and the capacitor is used to smooth the ripple from the DC. Total cost for materials is approximately $1.50, assuming you already own solder and a soldering iron.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Thu Sep 24, 2020 9:04 pm 



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mikejmoffitt wrote:
I think the confusion surrounding the description of the mod as making it "high TVL" might be alleviated a bit if it's phrased more specifically "decreasing spot size to increase TVL such that the pitch of the tube becomes the limiting factor".

I would be interested in replicating your results using some common arcade monitors. If the results are as sharp as you describe, then I expect they can not really be well conveyed in photographs, so seeing it in person would be the best way to judge it.


I'd describe it as increasing resolvable (as opposed to addressable) TVL by decreasing electron beam spot size from the original two phosphor triads width to be an electron beam spot size with a width of one phosphor triad.

This is very verbose though, and people need to get over the fact that two CRTs can have the same TVL, even though one CRT has a much higher mask dot pitch than the other CRT. PC CRTs can change spot size on the fly, as they switch between different resolutions, and clearly PC CRTs are not adjusting mask dot pitch on the fly. At 640x480 resolution, a PC CRT's resolution is 480 TVL, and when it switches to 1024x768 resolution, the resolution is increased to 768 TVL.

Using electronics to control for spot size in 15khz consumer CRT TVs is just taking a known technique from PC CRTs and porting it over to big chonker consumer CRTs. The research articles that I link in the OP are from the PC CRT industry 20 years ago.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Fri Sep 25, 2020 8:04 am 



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Downcry wrote:
Lots of confusion in this thread about TV Lines.

The term TVL, as it is (was) used in the industry, is for horizontal resolution.
It’s a function of the phosphor pitch of the aperture grill/shadow mask/etc.


But then how do you explain the thing that I mentioned a couple of posts above yours that an 800TVL and a 900TVL Sony used the same tube?


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Fri Sep 25, 2020 2:23 pm 


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SuperSpongo wrote:
Downcry wrote:
Lots of confusion in this thread about TV Lines.

The term TVL, as it is (was) used in the industry, is for horizontal resolution.
It’s a function of the phosphor pitch of the aperture grill/shadow mask/etc.


But then how do you explain the thing that I mentioned a couple of posts above yours that an 800TVL and a 900TVL Sony used the same tube?


TVL represents the number of resolvable lines (lines you can count with your eye), not the theoretical limit that the tube is capable of resolving.

Different electronics and circuitry will drive the tube with varying levels of precision.
This mod is trying to modify the electronics to squeeze more fidelity out of the tub since the factory electronics leave some precision on the table.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Fri Sep 25, 2020 4:14 pm 



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Downcry wrote:
SuperSpongo wrote:
Downcry wrote:
Lots of confusion in this thread about TV Lines.

The term TVL, as it is (was) used in the industry, is for horizontal resolution.
It’s a function of the phosphor pitch of the aperture grill/shadow mask/etc.


But then how do you explain the thing that I mentioned a couple of posts above yours that an 800TVL and a 900TVL Sony used the same tube?


TVL represents the number of resolvable lines (lines you can count with your eye), not the theoretical limit that the tube is capable of resolving.

Different electronics and circuitry will drive the tube with varying levels of precision.
This mod is trying to modify the electronics to squeeze more fidelity out of the tub since the factory electronics leave some precision on the table.


Exactly this. The phosphor/mask pitch is only one technical detail that can force an upper bound on the resolution, but it is very important to not think of phosphor triads as pixels on an LCD display. CRTs have no native resolution. So it is important that people do not think of phosphor/mask pitch as being the same thing as the CRT's resolution.

For example aperture grill tubes have continuous vertical stripes of RGB phosphor triads, so higher and higher voltage differentials between K-G1 and G2-G1 can drive increasingly higher and higher vertical resolution, but the breakdown voltage of K-G1 and G2-G1 will be the technical limit of the tube that forces an upper bound on vertical resolution, not phosphor/mask pitch. Of course, this is vertical resolution, which TVL doesn't measure (because TVL is just horizontal resolution), but for 240p gamers, the higher vertical resolution is the most visible factor of high resolution CRTs.

I'd love to see somebody try this mod on a 600 TVL aperture grill PVM. I bet a PVM G1 charged to -400 volts, the tube would draw at a 1000 TVL fidelity and create razor thin illuminated scanlines. I know that look is an acquired taste, but if you can have a potentiometer dial that lets you achieve both... why not? I mean, the fact that I got any visible results on a shitty, cheapy low end consumer curved slot mask CRT TV suggests the results on a 600 TVL aperture grill will be rockstar.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Fri Sep 25, 2020 8:58 pm 


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LukeEvansSimon wrote:
At 640x480 resolution, a PC CRT's resolution is 480 TVL, and when it switches to 1024x768 resolution, the resolution is increased to 768 TVL.


You know the tech, as you have shown in this thread, but at the same time this is the 2nd time you’ve related TVL to the vertical resolution. This is confusing.

As a bunch have already reminded, TVL relates to the horizontal resolution. I.e how many vertical lines contained in a displayed image can be resolved on the horizontal axis (to be absolutely clear, not talking about scanlines here, which define the limit of vertical resolution, i.e how many horizontal lines (in a displayed image) can be resolved on the vertical axis).

In your example, 640x480 corresponds to 640 TVL, 1024x768 1024 TVL.
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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Fri Sep 25, 2020 9:00 pm 



Joined: 07 Aug 2018
Posts: 25
LukeEvansSimon wrote:
I'd love to see somebody try this mod on a 600 TVL aperture grill PVM. I bet a PVM G1 charged to -400 volts, the tube would draw at a 1000 TVL fidelity and create razor thin illuminated scanlines. I know that look is an acquired taste, but if you can have a potentiometer dial that lets you achieve both... why not? I mean, the fact that I got any visible results on a shitty, cheapy low end consumer curved slot mask CRT TV suggests the results on a 600 TVL aperture grill will be rockstar.


So as I said I got this 14N2 here that is 500 TVL and it's not turning on.

Image

I got it out of storage today and it actually turned on for a very brief moment.

Image

The image stayed on for a short while, got bigger and then it shut itself off again. If somebody has a pointer in the right direction as to what could cause this it would be very much appreciated. Not exactly sure what causes this.

My idea would be to take my variac (which also is galvanically isolated) and use a voltage doubler to get around 650V rectified. With that I could experiment with different G1 voltages.


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Fri Sep 25, 2020 9:11 pm 


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Joined: 16 Jan 2014
Posts: 1041
Just curious, can you post photos of the entire screen with both stock and then modded voltage?


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 Post subject: Re: Mod a consumer CRT television to make it high TVL
PostPosted: Sat Sep 26, 2020 1:49 am 



Joined: 03 Mar 2005
Posts: 468
People might find this interesting for comparison. I think I found the very spot LukeEvansSimon had Alucard standing, although I put a different cape on him. It's right outside the last save point before the final boss.


This is a 20" shadowmask broadcast monitor advertised as 700TVL. In fact, it's the same one used in the Sonic CD shot Josh128 posted, which I originally took.

Spoiler: show
Image


And this is a 20" shadowmask broadcast monitor advertised as 900TVL. This is not the same one from the Sonic CD shot (that one is in storage).

Spoiler: show
Image



EDIT: Here, I made an image that's roughly to scale with the one in the OP:

Image


Last edited by SamIAm on Sat Sep 26, 2020 4:04 am, edited 1 time in total.

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