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It's present on all CRTs. Blooming is caused by failure of the high voltage regulation as the deflection system operates at or beyond it's stated threshold.

When a set is new, or still in good condition, it's much less noticeable because you can get a "bright" picture with a lower voltage. As a set ages, two important things happen. 1) The tube gets used up and it requires more and more voltage to make it as bright 2) the components in the high voltage stage get worn and become less effective at precise regulation of high voltage.

The Sony Trinitron FV310 has a voltage regulator that prevents the blooming, this makes it the consumer CRT with the thickest scanlines. Some people find it odd though, is a model with no bloom but also low tv lines (not quite the regular consumer set, but also not yet a pvm).

Here is pic of a bright image:


Photo from: https://socksfelloff.wordpress.com/2017/02/26/sony-trinitron-fv310-crt/

I don't recall (and it's been a while) ever seeing this when I was using pretty good CRTs as computer monitors, even high-end monitors and PVMs can't fix this?



This is interesting, I never made a connection between blooming and scanline visibility. I have a set with pretty bad blooming really causing major warping when content has uneven brightness, and it also has fairly uneven scanlines where they are quite clear in one part of the screen and completely washed away in others. Another TV with significantly less blooming has rather even scanlines across the screen. That's also related to HV-regulation?

Well, I don't want to rain on anyone's parade, so to speak, but there is no amount of "voltage regulation" that can compensate for the deterioration of components. No matter how good the set is, time will eventually take it's toll and the image will suffer. I don't know the details of the FV310 system, but if it doesn't "allow" blooming, then as the set ages and the components get worn, it would simply get dimmer and the regulator wouldn't allow for the voltage to exceed it's own stable voltage level. In fact, running a set brighter, because you are able to without blooming, will wear the set down much more quickly and I wouldn't do it myself. It's always best to keep a set at a reasonable brightness level if you are concerned about longevity.

IAC, All CRTs that of good construction (not cheap-o) won't show blooming when the voltage is set to a viewable threshold. If you're getting blooming at normal contrast levels, it's a sign that your TV has worn down components or it's just no good to begin with.

That being said, the HV sections of CRTs are very important for clarity of the image at normal brightness levels. Line count means nothing if you're regulation isn't stable enough to produce a clear image. If you think about the way the electron guns draws the image on the screen, you can imagine the system that controls the guns is also controlling how stable (or not) the resulting image is. PVMs and BVMs have more sophisticated deflection sections that generally perform better and last longer.

Thanks, interesting. I wish all TVs would have an hour counter like BVMs so I could see if mine with strong blooming has just been worn out.

Can you daisy-chain SCART TVs? SCART has lines for both directions and all my CRT TVs have some kind of menu option to output video from the 2nd SCART port. Could I hook up a RGB console on AV1, set the TV to output AV1 to AV2 and the use a fully-wired 21pin SCART cable and connect AV2 on TV-1 to AV1 on TV-2? I'm scared to try

You can easily figure out if the tube is worn out by measuring the high voltage while your contrast is set to a reasonable viewing brightness. If it's way high, then you've most likely got a worn out tube. If it's a normal (middle of it's service range) voltage, then you have bad components in the HV section or the set just wasn't that great to begin with. Most big name brand TVs of the 90's were pretty good when new, but we are all using old stuff now, so you have to take it in stride.

One day I'll buy high voltage gloves and a long ceramic tipped screwdriver and get into this, but right now I'm a bit scared to open a CRT. I'd love to fix convergence on my sets and one has a drooping corner that's not fixable from the service menu.

I have a set with an hours counter in the service menu, was around 15k. Tube is still plenty bright and apart from convergence for red being off in one corner it looks nice to me. How many hours would be considered 'worn out' for a 90s/early 2000s Sony TV?

That's fair. No reason to do anything dangerous that you don't feel comfortable with. But if you did, you would need to buy a special HV probe; they aren't super expensive.



Good question. Not sure.

So I finally (after 4 months, lol) calibrated the PVM-2950(for good this time). And I gotta say, this monitor's colours are better than I had initially given it credit for.

Now it's way closer(almost equal) to the fidelity of the small 600 TVL PVMs I had in the past (1344, 1354Q, 14M2U). WHereas at first it was more like a consumer set (ain't nothing wrong with that).
I first noticed the potential when using component, which looked better than RGB, now it was obvious that someone had messed about with the colour Cut and Drive of the RGB channel and that it's calibration was way out of whack. It made a huge difference to tune it correctly, as well as finding the right combo of brightness and contrast that'd make it shine at it's very best.

I gotta say, this is a dynamite display now. wow. I'm getting pretty stoked, finally. looks like a big ass version of say the PVM-1344. blindingly bright almost (this gotta be a lightly used unit), very potent depth to the picture and soft blanked lines. Very pleasing. It took me a bit to warm up to it since colours/contrast were off and texture is different than 2530, but now I dig. I'm impressed even

I'll try for real this time to upload good pics soon, lmao. I'm due to change my shit phone so I'll have a decent enough dslr soon

Worn tube strictly speaking would be one that needs to be "shot" to keep going.
https://www.youtube.com/watch?v=YikOY8WTnLU

I have a 1998 Trinitron monitor and even after all the years I was able to recalibrate the colors and get it to very decent luminance levels. It is said however that after 10000 hours a CRT loses 50% of its original brightness, but there are alot of factors and these tubes are way more reliable than we imagine.

Who says this? Sony's own service techs say their BVM's need tube replacement at 30,000 hours, and that is ONLY because the color accuracy goes down a little bit (which at that point, is still perfectly fine/good/great for retro gaming use like we use them for now since we don't really care or notice if the colors are only ~98% correct or whatnot).

https://www.extremetech.com/electronics ... ovations/5

That's for dot-trio shadow masks though, and it's really common in monitors. Most TVs use slotted mask and it is in fact brighter than shadow, but not as much as aperture grille. Also says that aperture grille monitors only lose 10% in the same time period, but it could just be marketing. It makes sense though, less blocked beam = less current to reach the same luminance level as other mask types = less phosphor decay.

I think it's also important to note that any projections are going to be based on a set running on all cylinders. As the sets age, you're going to have wear on the flyback and the potential for leaky (leaking AC that is) caps that aren't doing their job. All of that stuff is going to lead to higher voltages and much higher wear on the set. Also, the projections are typically based on operating level at a studio, so "bright" will be to where you can see the set in a pitch dark room. Most people are turning them up bright enough to see clearly in a well lit room.

Ive noticed a small scratch in the centre of the screen on my D-24.

Ii is really small but it creates a darker spot at it's location.

Do you think I should atempt to polish this out?

Don't know if anyone else has had success with this?

I wouldn't try to polish it out. If it's dark enough to leave a dark spot it's not possible to remove it with typical glass scratch remover.

I went through the process with my car a long time ago and learned how difficult it is to remove a scratch in glass. The rule of thumb is that if you can feel it with your fingernail (like your nail gets caught on it)
then you can't get it out with normal polishing means.

The only way to remove it is with cutting compound and that's both tricky to do and easy to take away too much of the surrounding material.

There are glass kits which fill cracks rather than remove them you might want to look into. They are clear resin kits that you put on with a vacuum device. That might work as they are designed to make windshields clear after filling a crack. I'm not sure what you would do to get it off if you didn't like the result, but some kind of solvent would probably work. I'm also not sure if the monitor screen has any chemical coating on it which might interact with the resin or be disturbed by an attempt to remove it with solvent (toluene, acetone, pentane).
Those are questions you should ask about before trying.


Good luck

Thanks

It really is very tiny like maybe not even quite a milimetre.

I'm not sure I could even fill it in with a resin.

I might just try some cerium oxide if that doesn't work I guess I'll have to live with it.

I polished out some scratches from a crt before using a 3 stage sanding process using sanding and polishing pads and a drill, but you have to do the whole screen I believe to make it even. Not worth it in this case, it's messy and takes hours.

That's more or less what I meant by normal polishing means. If it's faint enough it might work, or at least lighten the scratch enough to remove the shadow it casts. Mask the rest of the set really well cause that stuff on a drill makes a huge mess. (in the surrounding area as well)

I know lol it gets everywhere.

Well worst case scenario I can just get another D24 not like these things are expensive or hard to find is it

On another note, my bvm has started doing this werid thing when I first power it on where the colours are predominantly red and blue, if I leave it for a minute or turn it off and on again this goes however.

Not sure what this means?

could be as simple as a loose connection or as bad as a failing color gun. hard to speculate.

https://www.repairfaq.org/samnew/tvfaq/ ... me%20loose.

Ah ok well that's a bit worrying but thanks for your help

yw.

If you feel comfortable poking around inside, it could be as simple as reseating all the connectors. I would probably spray some deoxit in them as well.

I always thought of this as a feature, at least for older stuff. The first time I saw Turbografx games on an emulator, they were unrecognizable. I remember the ship in Aero Blasters seemed jagged, simple, cheap and primitive looking. I was so used to the bloom filling out the sprite, making it look smoother and more expressive than it really was. I genuinely thought there was something wrong with the emulator.

This is not really what's meant by CRT bloom. It's not like a bloom filtering effect done in a shader in modern games. The picture expands when the screen gets brighter, which distorts the entire screen.

Here:



On a CRT with strong blooming the white box would noticeable bulge around the white car as the image expands in this bright area.

I think it's a really unpleasant defect of consumer TVs vs monitors/good PVMs/etc. as it basically distorts and warps the screen, even if you'd have flawless geometry on the set. It's super noticeable if your console doesn't fill out the whole screen has the black border warps and distorts depending on the image content. For instance a bright sky means the top part of the picture expands horizontally more than the bottom part.

As other post pointed out, it's not exactly the same thing. What you are describing is bleeding. That's a color saturation issue and/or limitation of the set. Blooming generally effects the geometry of the picture. You can typically remedy bleeding, even on a cheap set by turning down the color knob until the scan lines are clear. How bright the colors of the resulting image are will be determined by the quality and state of the set.

If you want to test for blooming on a set with a composite input (sounds like what you are describing) turn the color all the way down and the brightness and contrast up. All sets will reach a point where the voltage is too great the geometry increases past acceptable deviation.

https://www.repairfaq.org/samnew/tvfaq/tvbloom.htm