24" Widescreen CRT (FW900) From Ebay arrived,Comments.

The DTP94 is a great meter for measuring any CRT. I still have one in my calibration kit for that purpose.
Newer meters designed for flat panels and projectors do not give such stable readings as the DTP94.

spacediver said:
Where did you read that peak white should be measured with a window rather than full screen. I can see this being relevant for plasmas that have automatic brightness limiters built in. Not sure about CRTs though. As far as I recall on my own display, windowed and fullscreen give similar luminance readings, though I'd have to double check.
Click to expand...
CRTs also use an ABL circuit, though the effects are usually far less severe than those found in plasma TVs.
CRTs should be measured using square patterns of a specific size for accurate measurements - especially gamma.

https://tech.ebu.ch/docs/tech/tech3325.pdf said:
The test inputs (patterns 4-1 to 4-19) are a series of test patches in measurement position 1 (Figure 3) in the centre of an otherwise black field. The patch is a square of dimension H/7.5 (13.35% of picture height, H)
Click to expand...
 
Thanks, that's a useful document. Yea, the ABL on the GDM line of CRTs works differently than plasma displays, from what I understand. In plasma displays, the brightness is reduced when a full field white pattern is presented. In the GDMs (and perhaps other trinitrons and CRTs), the tube shuts off completely once the beam current is too high. (I've actually done this during the G2 adjustment once when I slid the G2 way off to the right and made the screen too bright).
 
spacediver said:
Thanks, that's a useful document. Yea, the ABL on the GDM line of CRTs works differently than plasma displays, from what I understand. In plasma displays, the brightness is reduced when a full field white pattern is presented. In the GDMs (and perhaps other trinitrons and CRTs), the tube shuts off completely once the beam current is too high. (I've actually done this during the G2 adjustment once when I slid the G2 way off to the right and made the screen too bright).
Click to expand...
If you measure it, what you'll see is that as the pattern size increases, there is typically a gradual decrease in brightness.
With the best CRTs I've measured, the difference between a 1% window and a full white screen was <10% brightness.
Most plasmas lose at least 50% brightness on the same test.

And with CRT, as you reduce contrast, the strength of the ABL is also reduced.
With all of the plasmas I measured, the ABL was a fixed function which did not adapt to the contrast setting.
 
I guess what I'm afraid of is that I got a TV on its last legs. But it doesn't appear so. There's a bit of magnetization on the upper-left corner, and unfortunately there is no landing control. I'm wondering if I should get a degausser coil.

Also, there are some CA-100 units on eBay for not too much money. Is it worth getting one?
 
jbltecnicspro said:
Also, there are some CA-100 units on eBay for not too much money. Is it worth getting one?
Click to expand...

Don't waste your money. I don't think you'll be getting any additional functionality for your purposes. The only bonus is that if you get WinCATS to work, you can use the CA-100 with it and have it do the automatic white balance.

It's old tech anyway, the i1 display pro is probably superior as a colorimeter.
 
spacediver said:
Don't waste your money. I don't think you'll be getting any additional functionality for your purposes. The only bonus is that if you get WinCATS to work, you can use the CA-100 with it and have it do the automatic white balance.

It's old tech anyway, the i1 display pro is probably superior as a colorimeter.
Click to expand...

Okay then! That's good to know. :)
 
zone74 said:
If you measure it, what you'll see is that as the pattern size increases, there is typically a gradual decrease in brightness.
With the best CRTs I've measured, the difference between a 1% window and a full white screen was <10% brightness.
Most plasmas lose at least 50% brightness on the same test.

And with CRT, as you reduce contrast, the strength of the ABL is also reduced.
With all of the plasmas I measured, the ABL was a fixed function which did not adapt to the contrast setting.
Click to expand...

wait wut

i find this kind of hard to believe... testing right now

on my cpd-g520p:

77.7cd/m^2 full white screen
79.0 cd/m^2 36% abl
79.2cd/m^2 4% abl

everything set to default settings (last wpb adjustment was like 6 months ago)
 
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flod, when you say 36% abl and 4% abl, are you referring to the area of the white patch (relative to full screen)?

what do you mean by abl? (clearly not automatic brightness limiter)
 
my fw900 is too bright even with 0 value on the control panel
do i have to work with windas or flyback transformer?
can someone instruct me where i can find the flyback transformer(knob) for the voltage control inside the monitor?
 
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Question for my fellow CRT folks. So after trying to calibrate my big TV again, I was able to get it with a Delta E of 2-ish (2.3) for 100 IRE white and 30 IRE white. I have, however, noticed an issue with the screen. If I max out the white level of the screen and pull up the menu while doing a full white pattern, I'll notice the white balance drifts. The white turns pink-ish white when I pull up the TV's user menu and then goes back to normal again when I exit the menu.

Also, at full picture, I notice that the white balance drifts while calibrating as well - but more subtly (as in - the drift isn't very visible but the meter catches it). The x-axis will "bounce" from being too low, to right on target, and then too low, and then right on target (etc, etc). It's not SUPER far from target, but it's noticeable and none of my other screens do this.

Am I possibly looking at a weak gun? The television was a living room television for years, so I imagine that it has racked up some hours on it. It's not dim, but it's not a super-bright screen either. There's still some headroom on the unit, as pushing it too high on the white level leaves the screen too bright for normal use.

However, this is nothing compared to my 32-inch trinitron. The 32-inch screen has a LOT more headroom than the 36-inch screen does. This leaves me to believe that it may have been a game room TV or a bedroom TV.

I would like to look at getting a Sencore CR70 or CR7000 and maybe giving it a little bit of juice (after testing it of course) and getting it back up again. But for all I know, it could be a bad transistor. Any opinions on this? Unkle Vito - do you still read these boards?
 
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Not sure what the cause is, but so long as your TV is unaffected during actual viewing, why worry about it :)

not like you're going to be viewing material with the menu pulled up.
 
spacediver said:
Not sure what the cause is, but so long as your TV is unaffected during actual viewing, why worry about it :)

not like you're going to be viewing material with the menu pulled up.
Click to expand...

I guess you're right. Though it does have a misconvergence at the top left corner and a little bit of a landing error there too. According to the service manual there are disc magnets in the back to take care of the landing. I may try and adjust the one for the top-left corner. As for the misconvergence, I have some permalloy strips that should hopefully take care of it. I think I may investigate the picture issue further though, as I'm curious as to what's causing it. I still may end up getting a sencore CR70 or CR7000 just for fun. :)
 
yea a CR-70 would be cool (no real advantage to the CR-7000 other than that it lets you test all 3 guns simultaneously)
 
spacediver said:
yea a CR-70 would be cool (no real advantage to the CR-7000 other than that it lets you test all 3 guns simultaneously)
Click to expand...

Only reason I would consider a CR7000 over a CR70 is that, and newer documentation. Or not - maybe the CR70 documentation is just as good?
 
well if u can get a cr7000 for a good price go for it! But being able to test 3 guns at once is a time saver and nothing more, so keep that in mind.

As for documentation, the CR70 documentation seems very comprehensive to me.
 
spacediver said:
well if u can get a cr7000 for a good price go for it! But being able to test 3 guns at once is a time saver and nothing more, so keep that in mind.

As for documentation, the CR70 documentation seems very comprehensive to me.
Click to expand...

Gotcha. I actually got a Belltron 8080A coming in the mail to me. I'm going to go to Goodwill ($3 CRT TV's) and pick some units up to practice on. I think we should probably start a CRT enthusiast site or something... :D

In other news (regarding the TV situation)... For whatever reason, the white balance adjust has improved. No "pinkish" whites when I pull up the menu at full Picture. However, I think that the blue gun may actually be the weak gun. The service menu actually allows you to turn on and off the guns (GON, RON, BON - just don't turn all off at once!! :D). The blue picture is by far, the blurriest of the bunch, and it's worsened when I increase the drive.
 
Same with mine:

14biadi.png


I'm not sure this is indicative of a weak gun though. If you look at the spectral sensitivity function of the human eye, you need much more radiance in the blue wavelengths to achieve the same perceived brightness as, for example, the green wavelengths. This means more photons required from the blue phosphors, which means, all else being equal, more beam current from the blue gun (which would mean more electron back scatter, a less focused beam, and a blurrier image). Of course, not everything is equal - each phosphor type has its own radiant efficiency, and if it turns out, for example, that the blue phosphors are much more sensitive (i.e. emit more photons per incoming electron), then this would counterbalance the lower sensitivity to blue light of the human eye.
 
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Noted. Thanks for the very concise explanation. :)

That does make sense then that the blue would be a little blurrier than the others. I guess the only way to find out is to test it huh? Now that I think about it, when doing the focus adjustments on the Artisan and F520, I do remember that blue wasn't as crisp as green was (don't remember red). But the difference between the blue gun and the others on the TV is pretty stark in contrast. Green is the sharpest, red is close, but blue is just downright blurry compared. I guess what I really should do is readjust the white balance for D65 and THEN run through the guns and see how blurry blue is. I did mess a little with the drive settings, so I'm sure I threw it off.

Excited for the Beltron to come in. :D
 
Yea I'm curious to hear about your experience with the Beltron - maybe consider it training for the CR-70/7000 :)
 
Is it worth getting one used? I've been reading the replies in my thread, and am already having second thoughts if it's too much effort to maintain. I also have no clue on how well CRT.Emudriver will function with it.
 
I've bought three used ones, one of which clearly had tonnes of hours on it, and had been recently dropped. I paid $30 for it. Other than the occasional fizzy losing focus pop, which doesn't happen often, it works perfectly. The other two may just as well be brand new as far as I can tell. I paid $300 and $200 for them, respectively. Best to ask the seller if it has any issues with it.
 
BlackGuyRX said:
Is it worth getting one used? I've been reading the replies in my thread, and am already having second thoughts if it's too much effort to maintain. I also have no clue on how well CRT.Emudriver will function with it.
Click to expand...

I've only had one FW900 but it's pretty much perfect. I also have a GDM-F520, and a GDM-C520K Artisan. Of the three, I think the Artisan has the most hours on the tube and it's still pretty good. Definitely no functional issues. CRT monitors are a crap shoot. But of the ones I've owned/had in my possession:

- Dell M782 (unknown tube - wasn't in to CRT's as much at the time I had it, so I never looked)
- Dell M991 (Phillips tube)
- Dell P991 (Sony Trinitron Rebrand)
- Compaq 17 inch (not sure either)
- NEC 17-inch
- IBM PS/2 12 inch
- LaCie Electron Blue II (22 inch Diamondtron rebrand)
- Nokia 17-inch (Hitachi rebrand)
- Sony GDM-FW900
- Sony GDM-F520
- Sony GDM-C520K Artisan

These tubes have all been in my possession within the last three years. Only three of them really stand out to me for issues. The NEC monitor had a dying flyback, the Dell P991 was going dim (couldn't reach luminance spec on the 5000K white balance adjustment no matter how hard I cranked it), and the IBM monitor for a dying flyback. All other monitors were serviceable with no functional issues. EDIT: The Nokia was pretty used up too - but it still could produce a decent enough picture.

Maybe I'm just lucky, but that's my experience. Unfortunately, you don't know what life the tube lived. You won't know until you get it and see it in person. If you can - get an older FW900. They have the better tubes. A new DTP-94 can be had on eBay for not much money (hey - if you're blowing money on the FW900 you may as well) and get a WinDAS cable and learn to do a white balance adjustment.

When you go through the White Balance Adjustment, you adjust the number one culprit of most Trinitron monitors - the darned G2 level. Sounds scary, but it isn't.
 
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BlackGuyRX said:
Is it worth getting one used? I've been reading the replies in my thread, and am already having second thoughts if it's too much effort to maintain. I also have no clue on how well CRT.Emudriver will function with it.
Click to expand...

Have a question - do you NEED a VGA monitor? How well does MAME work with RGB monitors? I'm wondering if you could just assemble your own? That would be awesome. :)
 
I just bought linear polarizer sheet for my FW900 http://allegro.pl/folia-polaryzacyjna-polaroid-samoprzyl-100x50-cm-i5540240636.html

earlier I did tests with small sheets and circular polarizer was way to go but rather hight price, it being from abroad and lack of option with adhesive put whole thing on hold. I will put this linear filter instead. Linear filter was quite nice too, even without phenomenal glare reduction it would at least put it on par with other CRTs.

Transmittance is 48% so maximum brightness will be much much lower and so with given amount of brightness eg. 120cd/m2 it will be much much more blurry because with CRTs the higher output power from guns the more blur and with filter to get 120cd/m2 screen will have to be as bright as ~250cd/m2... which is very easily doable because FW900 is brightness monster :D

In any case I should have it somewhere in the middle of next week and will post results then. So far I brought on my desk some cheapo LG (Flatron 915FT Plus) and it absolutely destroys FW900 in picture quality and it is solely due to it having actually black screen. How can FW900 compete when it have worse black when it is off than this LG have black on and around white edge. Yes, some cheap-ass LG have better black despite flaring and inner glass reflection than FW900 when it is totally off... Imho all this praise FW900 gets for its picture quality is totally unjustified. Seeing normal proper multimedia CRT directly next to FW900 (which sacrificed picture quality for sharpness) have opened my eyes: FW900 have actually pretty bad picture quality XD XD But nothing I can not fix... I hope...
 
Well, so I went to Good Will today and bought a $3 Apex 27-inch CRT television. First thought when I took the television apart is that it's fucking disgusting in there. The previous owner(s) were definitely smokers. Grime was literally caked around the flyback transformer. It was so bad that I couldn't read which pot was the G2 or which pot was the focus (had to try em out).

With that out of the way, I'm disappointed to say that my test has been a failure with the Beltron. The tube's guns tested with great emission levels, and had no shorts so I couldn't really do much to see this baby really "work."

That said, I did play around a little bit and here are my observations:

1. The neck board of a CRT comes off pretty easily.
2. Finding a socket to fit the tube was also easy.
3. When doing any cleaning or rejuvenation process(I did the more gentle "clean" process on the Beltron) - always have the tube face down. If you leave it upright, filament may fall down in the neck area and short when you turn on the television (this happened to me the first time I did a clean for the tube). The next time I ran the cleaning process, and burned off some stuff, I had the tube face down and the tube didn't even blink when I reassembled it the second time.
4. If a CRT is already good, working it with a restorer will do NOTHING (and if you fuck it up, you could make it worse). I think this is kind of a "duh" thing, but thought I'd mention it here. If it ain't broke, don't fix it.

All in all, I had fun. Will post a pic later. I'll be tossing this TV to the curb though, as it truly is a work of disgusting art under the hood. :mad: Nasty smokers.

EDIT: The tube is in great condition though. Weakest gun is the Red, but its emissions were far above what the manual states is good emission levels. If I was making an arcade cabinet, I would definitely consider yanking the tube from this television. It's a Thomson 27-inch shadow mask - round. I don't really know what else to say. Picture is great, and if it wasn't so nasty I'd call it a keeper and do a grayscale calibration.
 
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Well just looked at my adapters and none of them do the newer Trinitrons. Darn... Oh well. It did come with a universal lead, so I can probably just make my own.
 
just had a major breakthrough in my "sharpness" testing.

The main issue I was having was this:

My setup is able to take very high magnification images, and then analyze these images to determine how sharp they are. The focusing is done manually, with a high end micrometer (this one), attached to a linear translation stage. Then, using the Canon EOS utility, I can see a live preview window of what my camera is seeing, and I can zoom in very close on the target and adjust the micrometer until the focus is perfect.

This is what my setup looks like - the target I'm measuring is actually a ronchi ruling, which is a transparent slide with a set of perfect square wave gratings. You can see the live preview in the top left of the screen.

14jxa8p.png


The problem is that I'm never quite sure when the focus is perfect. There's a range of about 15 microns of movement of the camera where the image looks very similar. My concern is that the noise level of my visual system may be above the difference levels of whatever sorts of targets I'm comparing. For example, if I'm measuring the sharpness difference between a DVI-VGA and a DVI-BNC cable, if the actual difference in sharpness between these two cables is less than the difference in sharpness I'm able to perceive with manual focus, then my method won't work.

So what I did was to set up a system where a screenshot is automatically taken every second of my desktop (which includes the live preview window). Matlab then reads this image, and supersamples the image using the slanted edge method (described beautifully here, (read from page 7 onwards)), and then measures the Edge spread function (how gradually the image goes from black to white). By using a fitting procedure, I can measure the standard deviation of this function, and try to minimize the standard deviation while I'm adjusting the micrometer real time. By adjusting the micrometer until I get the lowest standard deviation, I'm able to achieve the perfect focus without guess work.

After a lot of work, I was able to get the system very stable, and it's very sensitive. The target angle I was using (about 1.6 degrees) gives me a supersampling factor of about 36, which is huge!. When I adjusted the micrometer by 10 microns, the standard deviation changed about 20 units, which is at least 10 times more sensitive than I'm able to achieve visually. I've also decided to stick with the standard deviation of my Edge spread function as my primary measure of sharpness. The MTF (modulation transfer function) is superfluous, and has other issues that I won't go into here.
 
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So are you trying to measure the sharpness of the CRT under certain conditions? Sorry - this is very technical and I'm getting a little lost in the details.
 
Yes, I'll be able to measure the sharpness, using an objective quantitative measure, under various conditions.

for example:

diff types of cables.
diff refresh rates
diff video cards
with or without anti glare
diff luminances of the white part of the pattern (my patterns will be a patch of white bordering a patch of black)
diff sizes of the pattern (e.g. I think the image will be less sharp when there's a large white patch bordering a black patch, vs. a small white patch bordering a black patch).
 
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jbltecnicspro said:
Well just looked at my adapters and none of them do the newer Trinitrons. Darn... Oh well. It did come with a universal lead, so I can probably just make my own.
Click to expand...

wait, you're thinking of using the Belltron with trinitrons? I know next to nothing about rejuvenators, but I always just assumed you needed a sencore for those.
 
spacediver said:
wait, you're thinking of using the Belltron with trinitrons? I know next to nothing about rejuvenators, but I always just assumed you needed a sencore for those.
Click to expand...

You can use anything with any CRT. I've read that Beltrons are very gentle with their cleaning process, and among the more gentle rejuvenators out there. Sencores - the modern ones (CR70 and CR7000) - can be used on them, but the older ones should not because of how they blast the tube. They're too strong. Trinitrons are fragile, apparently.

Any CRT rejuvenator will hook up to a CRT monitor. It's just a matter of connecting the correct pins. Most rejuvenators come with socket adapters to make it easy for this. So far, I have tried to hook up three TV's. Two of them were a success - the Sony was not. I have no socket adapter for the new Trinitrons - just the old ones.

But really, it shouldn't be hard at all. All I need to do is look at the schematic of the Beltron universal adapter, and look at the Sony schematic for the socket (in the service manual) and BAM - I'm done.

In general the Sencore CR70 and CR7000 are among the best TESTER's. Beltron is apparently a good cleaner and rejuvenator. It's not as good at testing though because it doesn't test all the parameters that the Sencores do.
 
spacediver said:
Yes, I'll be able to measure the sharpness, using an objective quantitative measure, under various conditions.

for example:

diff types of cables.
diff refresh rates
diff video cards
with or without anti glare
diff luminances of the white part of the pattern (my patterns will be a patch of white bordering a patch of black)
diff sizes of the pattern (e.g. I think the image will be less sharp when there's a large white patch bordering a black patch, vs. a small white patch bordering a black patch).
Click to expand...

This will be awesome! Very excited about this.
 
spacediver said:
very interesting!
Click to expand...

Just figured out the new Trinitron setup and got it working. Very easy, and I'm very very thankful that whoever owned my Beltron marked the cables (red, green, and blue cathode cables were color coded, and the other three were educated guess work).

In my opinion, every CRT enthusiast/hobbiest would do well to own a tube restorer/tester/rejuvenator.

As for which ones to get for the Trinitrons, common wisdom that I've seen on other forums is that Trinitrons are very fragile. Beltron is one of the few older restorers that you can get for cheap that are gentle enough for the Sony's to be useful.

Apparently there was a Sony service bulletin back in the day that referred to the Beltron as "Lazarus". :D

Sencore CR70 and CR7000 are other units that are good for them as well. I haven't read any direct comparisons between the units, but it is my understanding that the Beltron rarely ruins tubes (assuming you know what you're doing of course) and that tubes that they have fixed have lived long lives. Common forum wisdom seems to point the finger at the fact that the Beltron system has two restoration modes - a "Clean" mode and a "Restore" mode. Most working tubes who need a kick are fixed with the "Clean" function. Another neat feature about the "Clean" function is that you can manually control how much voltage you give (it's a pure-analog, non-stepped potentiometer) the tube during the cleaning process. When it comes to testing, however, the Sencore units wipe the floor with the Beltron. Beltron can only explicitly test for emission levels in the guns, and as such, is much more demanding on the user to interpret what's going on. As an example, when you test the emissions levels on the guns, the needles should smoothly and swiftly rise to their peak and stay there. If there are any needles that "bounce" on the way up, it indicates there could be some shorting going on. But really - it's up to you, the user, to figure it out.

The Sencores, on the other hand, will just flat-out tell you what's wrong with the tube. They will test a number of things - emissions, cutoff tracking, color tracking, H-K shorts, etc. As such (I have never used one, mind you), I would consider these units more user-friendly. Eventually I will probably get a CR70. I see no need for a CR7000 unless I find a really good deal on one. I haven't read too much into the manual of the CR70, but unless I'm mistaken, the CR7000's only leg-up on the CR70 is that it can restore all three guns at once. I'm quite sure that the CR70 can test all three guns (otherwise it could never test color tracking - which measures all three guns together and calculates how far the weakest gun is from the strongest). I mean - the Belltron tests all three guns at once, for crying out loud! :) The Beltron can only rejuvenate one gun at a time though. I really need to take some pictures to give a better visual as to what I'm talking about...

Getting a tester that's older than a CR70 probably isn't recommended because I've read of older Sencores being absolute brutes with their restoration process on CRT's. And so are the other brands. With the exception, of course, of the Beltron system. I have the Model 8080A, in case anyone is interested. There were only two models. The 8080A and the other one, which is a 29xx I believe. I think there is one on Ebay, but it looks like an 8080A
 
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spacediver said:
Same with mine:

14biadi.png


I'm not sure this is indicative of a weak gun though. If you look at the spectral sensitivity function of the human eye, you need much more radiance in the blue wavelengths to achieve the same perceived brightness as, for example, the green wavelengths..
Click to expand...

Yes but the balance of luminance output is something like 22% red, 71% green, 7% blue in order for the white you need for sRGB.

So while it takes a lot of blue energy to be bright, we don't need a lot of it for an accurate picture.
 
obiwansotti said:
Yes but the balance of luminance output is something like 22% red, 71% green, 7% blue in order for the white you need for sRGB.

So while it takes a lot of blue energy to be bright, we don't need a lot of it for an accurate picture.
Click to expand...

Good point.
 
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