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

Derupter

Limp Gawd
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I received the Multicomp displayport plug and well ... It seems it's a fail. :dead:

View attachment 203929

It has a lock, dimensions seem better than the one on the Delock adapter, it has a plastic cover that can be clipped BUT it is apparently intended to use with some molding around the cables and a copper foil on the top of it, instead of a solid shielding cover. On the top of that I also need a molded part around the cable end to secure it inside the plastic cover, and I couldn't find anything fitting. Probably something molded during the assembly process and not for sale as a spare part.
For reference here is the displayport plug of the cable provided with the Sunix adapter:

View attachment 203931

Unless someone has a genius spark, I suppose connecting a displayport cable cut in half to the box of the adapter is the only practicable way to fix it.
You can use some hot glue to block everything and adhesive copper foil to shield, or use the shielding cover (if it fits) and the molded part around the cable end of the original connector.


Digital Foundry is back with more CRT coverage:

(Starting around 22:55 John Linneman mentions using the Vention USB C to VGA adapter with success.)
He has probably read about it here, but the model shown in the video can't do more than 360 MHz.
Some information about Vention adapters:

USB-C to VGA (Model code CGMHA) with Lontium LT8711X-B
This is the model we talked before with performance comparable to Sunix DPU3000

USB-C to HDMI(1.4) and VGA (Model code CGKHA) with ITE IT6562 + VIA VL100
This is the old version of the HDMI+VGA and can't do more than 360 MHz, DAC should be 10 bit
This is the model shown in that video

USB-C to HDMI(2.0) and VGA (Model code CMFHB) with Lontium LT8712X
This is the new version of the HDMI+VGA, the new Lontium chipset should have the same performance as the LT8711X-B
I didn't mention it before because it was almost unavailable out of china
 

spacediver

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He has probably read about it here, but the model shown in the video can't do more than 360 MHz.
Strange, he did tell me he was able to get 2304x1440 @ 80 hz. It's possible he's using CGMHA and posted a link to a different one not knowing that they were indeed different.
 

Derupter

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Strange, he did tell me he was able to get 2304x1440 @ 80 hz. It's possible he's using CGMHA and posted a link to a different one not knowing that they were indeed different.
Can be that Amazon web page description is for the old model,but they actually sell the new model (CMFHB) which is aesthetically the same.
Or maybe they have both models and you don't know what is shipped.
 
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3dfan

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2304x1440 @ 80 hz is about 383 mhz, not far from 360, if possible, can you please ask him to try something like 2560x1600 72hz? its about 424 mhz and would be a good reference if that Vention model can support those pixel clocks the dpu3000 can, i know fw900 can support that with the dpu3000, because i have tested by myself, if he fails the 2560x1600 72hz test, can try 2560x1600 68hz which is 398hz, and if pass this test would mean that vention he used is 400mhz practically
 
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Wirysage

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You can use some hot glue to block everything and adhesive copper foil to shield, or use the shielding cover (if it fits) and the molded part around the cable end of the original connector.




He has probably read about it here, but the model shown in the video can't do more than 360 MHz.
Some information about Vention adapters:

USB-C to VGA (Model code CGMHA) with Lontium LT8711X-B
This is the model we talked before with performance comparable to Sunix DPU3000

USB-C to HDMI(1.4) and VGA (Model code CGKHA) with ITE IT6562 + VIA VL100
This is the old version of the HDMI+VGA and can't do more than 360 MHz, DAC should be 10 bit
This is the model shown in that video

USB-C to HDMI(2.0) and VGA (Model code CMFHB) with Lontium LT8712X
This is the new version of the HDMI+VGA, the new Lontium chipset should have the same performance as the LT8711X-B
I didn't mention it before because it was almost unavailable out of china
So do these usb-c to VGA adaptors work if a graphics card (like my r9 290) can output display port signals? The card doesn't have a usb-c port or the mobo. Does this mean that if I team this adaptor with a usb-c pci card it might allow the graphics card to output display port over usb-c?
 

Derupter

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2304x1440 @ 80 hz is about 383 mhz, not far from 360, if possible, can you please ask him to try something like 2560x1600 72hz? its about 424 mhz and would be a good reference if that Vention model can support those pixel clocks the dpu3000 can, i know fw900 can support that with the dpu3000, because i have tested by myself, if he fails the 2560x1600 72hz test, can try 2560x1600 68hz which is 398hz, and if pass this test would mean that vention he used is 400mhz practically
The limit factor is always the digital receiver of these chipset.
If the CGKHA really has the IT6562 chipset it can't go over 360 MHz, the digital receiver can't do more than that.
If it goes over 360 MHz it means that the chipset is one of the Lontium and the Ventium specs are wrong.
Like Spacediver said, maybe that guy has simply confused his adapter with another and showed a wrong adapter in that video.
CGMHA and CMFHB with Lontium chipset can do up to 720 MHz with their digital receiver like DPU3000, how much can do the DAC only tests will tell.

Can the Delock 62967 do 1600 x 1200 at 95hz on a AMD R9 290 ?
Yes it can do more than that, but only if the adapter works properly with your graphic card.
If the displayport signal of your card is not strong enough, the adapter can't work properly over 180 MHz (no more than 1600x1200 66 Hz) and you need to replace the cable or return the adapter to the seller.
If the adapter works without problems you can go up to 340-350 MHz (example 1920x1200 100 Hz or 1920x1440 85 Hz)

So do these usb-c to VGA adaptors work if a graphics card (like my r9 290) can output display port signals? The card doesn't have a usb-c port or the mobo. Does this mean that if I team this adaptor with a usb-c pci card it might allow the graphics card to output display port over usb-c?
Yes you can connect any USB-C adapter to any displayport graphic card but only using special cards like Sunix UPD2018 or Delock 89582, you only need a free PCI Express x1 slot.
 
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SH1

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Have a little bit of good news from the big Radeon Adrenalin 2020 update.

The pixel clock cap for custom resolutions in Radeon Settings was lifted, for Sunix+5700 xt anyway. I was able to create some silly resolutions like 2560x1920@70hz.

But it still has the other issues I brought up a couple months ago:

It still ignores anything I put in CRU when using the Sunix, so all custom resolutions have to be added via Radeon Settings. CRU overrides still seems to be working on HDMI. Except for interlaced resolutions, which don't work no matter which program you create them with. Hopefully they still work on analog capable cards like the 380x, I'll be checking on that soon.

HDMI gave some other problems, like for my Nano GX adapter, I strangely couldn't make resolutions over 1280x960, then with the Benefei adapter, I couldn't switch to YCbCr, which the adapter needs to display proper color.

All those problems I just mentioned don't exist on the new Nvidia GPU's, so you guys can figure out where you need to look if you're buying a new GPU for your CRT.
 

kohan69

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My FW900 is having sideways motion/jitter at lower than 100Hz refresh rate, and at higher, it slowly fades in and out of focus on the corners a bit, speed depends on refresh. Before I do a full recap, does anyone know which area/board/component/caps are responsible for this?
 

strayan

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So do these usb-c to VGA adaptors work if a graphics card (like my r9 290) can output display port signals? The card doesn't have a usb-c port or the mobo. Does this mean that if I team this adaptor with a usb-c pci card it might allow the graphics card to output display port over usb-c?
Graphics card output analog VGA if they have a displayport++ so you don’t necessarily need a usb c adapter just a passive dp to d-sub cable
 
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Derupter

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Graphics card output analog VGA if they have a displayport++ so you don’t necessarily need a usb c adapter just a passive dp to d-sub cable
Displayport++ has nothing to do with analog VGA output, it is only for output HDMI and DVI signals through passive cables, for digital to analog conversion a true active adapter is required.
 

Strat_84

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My FW900 is having sideways motion/jitter at lower than 100Hz refresh rate, and at higher, it slowly fades in and out of focus on the corners a bit, speed depends on refresh. Before I do a full recap, does anyone know which area/board/component/caps are responsible for this?
It's hard to guess and it might not be a capacitor issue but the potential candidates are G board (power supply stability issues) then D board (dynamic focus & horizontal deflection), then N board (signal controling deflection come from there).

If you go with a full recap, my excel sheet should be helpful, I attached it to the post. Left column: the electrolytic capacitors on each board. Right column: the ones I used as a replacement.
Further comments:
- You may use any brand/series you like but I strongly advise to use Rubycon YXF series without increasing the operation voltage for capacitors located on a voltage line after a Low DropOut voltage regulator (unless well, the original voltage capacitor and the higher voltage one have the same ESR). These regulators need capacitors with a reasonable ESR to operate properly and this serie/brand seems to be the only quality one with both a long lifetime (4000-5000h @105°C) and not-so-low ESR.
- C569 is a specific case as even an YXF capacitor has an ESR somewhat too low (0.40 on the datasheet, real life value 0.3 ohm, to compare to about 0.8-0.9 ohm for the original old Rubycon YK on the board). I put it in series with a 1 ohm resistor. Result: voltage variations decreased from about 20mV to 10mV, I suppose you can still get away with the 20mV variations though. Your choice.
- I replaced many of the capacitors with higher voltage ones, for the sake of performance and durability, but this is not mandatory at all.
- Panasonic capacitors named FR-L are actually part of the FR series, it's just a tag I put there to differentiate longer 1000µF/25V models from the standard ones. Both are suitable, but there may not be enough room for the long model on every board if I remember correctly.
- C559 can actually be replaced by a polypropylene film capacitor, it will be much more durable and there's actually some room planned on the board for this. Not sure if this brings any display improvement, but it can only make it better.
- While you're at it I strongly recommand to replace C919 with a good quality ceramic capacitor (ceramic type B/X5R or type R/ X7R). I suspect this may fix the G2 drift issues. Suggestion: Kemet C331C472KGR5TA, there were also good single layer Murata capacitors but they must be discontinued by now and they were bulkier.
- Be careful when desoldering on the D board, it's a double layer board. You'll need a powerful solder iron and maybe to add some flux or some leaded solder to remove components without ruining the tracks with prolonged heating.
- Your issues might have something to do with some polyester film capacitors on the D board. They have some transparent plastic through which you can see an aluminium foil. I've seen some of these getting yellow (especially on the top) and maybe some sort of oily substance spreading under the plastic. Even though the ones I removed seemed to measure fine, this is pretty suspicious. There's one of these stabilizing the current input of the flyback (C921).
 

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kohan69

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you're a god damn hero, Strat_84
I hope to find a post that someone fixed the horizontal shaking issue without redoing everything first, but either way your post will be really helpful. What was the issue on yours?
 

Strat_84

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Thanks, I'm glad to share this. :)

My screen didn't have much of an issue except old age, and its previous owner being a retard calling himself "electronician" and messing with the inside. He desoldered perfectly working memory chips for weird reasons (maybe to try saving the data ?), and broke a few lines in the flat cables linking the boards in the dismantling process. That led to the display contracting itself vertically. The G2 voltage was also completely messed up but this is pretty common.
It took a long time before I found the cable issue and I had already made a full recap for electrolytics, and many film and ceramic capacitors. Some replacements weren't really necessary, but I intended to restore that screen as completely as possible anyway, and to investigate the boards to find if some limited improvements were possible while I was on it.

One obvious detail I forgot to mention about the replacement of C919, you'd be replacing a leaky crappy worn out capacitor with a quality new one, that means a white point balance procedure with Windas is mandatory after the replacement.

Also, you should check the boards for bad solders, there are often some. In your case, according to your description I'd rather think about some capacitor issue on a voltage line. Maybe noise related to horizontal deflection or vertical deflection, or both, is making its way back on these lines and reaching areas it shouldn't. But it's only a guess, you'd need an oscilloscope to check this. ;)
 
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DooLocsta

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This cheap one from Amazon. CableDeconn Active DVI-D Link 24+1 Male to VGA Female M/F Video Cable Adapter Converter https://www.amazon.com/dp/B01DW2BJWU/ref=cm_sw_r_cp_apap_3ItFuSHXOmZHb
After reading the reviews on this I decided to try out this one https://www.amazon.com/gp/product/B07D3XZ9SD/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 and I am pleasantly surprised. I have a P1110 and I was just shooting for 1280x1024@110Hz but this handles the max res 1800x1440@75Hz fine. Pretty nice for $8
 
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After reading the reviews on this I decided to try out this one https://www.amazon.com/gp/product/B07D3XZ9SD/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 and I am pleasantly surprised. I have a P1110 and I was just shooting for 1280x1024@110Hz but this handles the max res 1800x1440@75Hz fine. Pretty nice for $8
I know that one of their HDMI adapters required YCbCr instead of RGB to hit high clocks. Is yours the same way?

Anyway, just so you know, 1280x1024 is a 5:4 resolution. You want to use 1280x960 or 1366x1024 instead.
 

DooLocsta

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This monitor seems to do really well with 5:4 but I have updated to 1366x1024@110Hz and all is good. I am not sure on the YCbCr, is there something I can test? I am running a 1080Ti
 

P1x3L

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The top Eizo & Iiyama CRTs seemed better than any Trinitrons I've seen. Anyone own both an FW900 & either and Eizo or Iiyama? The Iiyama visionm pro 514 is the best I've seen.
 

SH1

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The top Eizo & Iiyama CRTs seemed better than any Trinitrons I've seen. Anyone own both an FW900 & either and Eizo or Iiyama? The Iiyama visionm pro 514 is the best I've seen.
Had Iiyamas before Sonys, because were less expensive. Fine displays. However, as far as absolute best computer CRT, as far as I know -- Sony F520 which features a unique, for aperture grill, 0.22 pitch. And the FW900 with a picture still close enough to its sibling and just strikingly bigger. (I remember reading that Sony showed off a 0.15 pitch 4:3 tube at a trade show, but unfortunately it never made it to market before the end.)

I do not believe the Diamondtron tubes were as refined as the Sonys. FWIW...I remember being able to make out a visible curvature on the inner aspect of their flat screen tubes, which I cannot make out on the Sonys.

I recall hearing some saying Shadow Mask tubes being sharper for text.
 
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This monitor seems to do really well with 5:4 but I have updated to 1366x1024@110Hz and all is good. I am not sure on the YCbCr, is there something I can test? I am running a 1080Ti
I'm sure it does "well" with 5:4, it's just stretched horizontally on CRT's because they're 4:3.

But YCbCr will be in the resolution tab, under "color format"
 

Yuriy83

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The top Eizo & Iiyama CRTs seemed better than any Trinitrons I've seen. Anyone own both an FW900 & either and Eizo or Iiyama? The Iiyama visionm pro 514 is the best I've seen.
I haven't seen Eizo & Iiyama, but FW900 doesn't have the best quality amongst trinitrons to be honest. I like F520 better. FW900 has this weird phosphor / coating compared to other models. F520 and even G500 have better percieved contrast and color saturation in my opinion, while handling reflections better.
 

SH1

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I haven't seen Eizo & Iiyama, but FW900 doesn't have the best quality amongst trinitrons to be honest. I like F520 better. FW900 has this weird phosphor / coating compared to other models. F520 and even G500 have better percieved contrast and color saturation in my opinion, while handling reflections better.
F520 has a proper coating. FW900 has that glued on plastic film. Maybe Sony would have addressed this in a successor, but then it all ended.
 

P1x3L

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I wonder if there are enough enthusiasts online to justify producing the next top-end CRT...
 

Strat_84

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Don't dream too much of that. The expertise on high performance CRTs tubes has probably been lost by now. All factories have been dismantled, and as far as I know the only few CRT tubes that may still be manufactured are low end oscilloscope displays. On the top of that CRT displays require some components with very specific characteristics (horizontal deflection transistor for instance) that have been discontinued as well. It's not just dependant of a single company, the entire production chain is gone.
 

P1x3L

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Don't dream too much of that. The expertise on high performance CRTs tubes has probably been lost by now. All factories have been dismantled, and as far as I know the only few CRT tubes that may still be manufactured are low end oscilloscope displays. On the top of that CRT displays require some components with very specific characteristics (horizontal deflection transistor for instance) that have been discontinued as well. It's not just dependant of a single company, the entire production chain is gone.
There's no way a bunch of the engineers who built Eizo, NEC, Iiyama, and Sony CRTs aren't still alive...
 

Yuriy83

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There's no way a bunch of the engineers who built Eizo, NEC, Iiyama, and Sony CRTs aren't still alive...
That's not the problem. They would have to rebuild many production lines to produce various components. It wasn't profitable for them to maintain in the 2000s, it would be even less profitable to build everything from scratch today. A CRT display today would have to cost a fortune to justify the expenses. Not happening.
 

XoR_

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The top Eizo & Iiyama CRTs seemed better than any Trinitrons I've seen. Anyone own both an FW900 & either and Eizo or Iiyama? The Iiyama visionm pro 514 is the best I've seen.
Color quality of FW900 is pretty mediocre as is contrast. It is due to phosphors they used in this model. Some other Trinitrons I used like IBM P275 and Dell P1110 used much better phosphors/filters and color quality was much better.
Diamondtrons used even better phosphors and also different gun layout giving to better colors/contrast and sharpness respectively.

Actually it is only the larger and widescreen aspect ratio that makes FW900 so desirable. Other than that there are better and much cheaper alternatives available.
 

XoR_

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F520 has a proper coating. FW900 has that glued on plastic film. Maybe Sony would have addressed this in a successor, but then it all ended.
When I had IBM P275 friend of mine bought some older non-flat Trinitron and it used exactly the same phosphor and coating as GDM-FW900 and thus also had inferior color/contrast.
If CRT era was allowed to continue some more then we would definitely have much better displays to choose from today, including Diamondtron offerings. This is so sad :(
 

XoR_

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I wonder if there are enough enthusiasts online to justify producing the next top-end CRT...
Not happening
Besides, right now we are at the brink of OLED explosion and you also need to have wide-gamut and high dynamic range capabilities while CRT are quite dim to begin with and putting even more saturated phosphors would make these displays even dimmer.
Oh, and did I mention "green" or "eko" regulations? CRT consume tons of power and use (considered to be) hazardous materials in their production... on top of that there is fabrication facilities being lost issue.

Some small production could be done if some millionaire insisted on making this happen but those people usually do not do stuff that would only make them loose their money, they also need to have some profits or at the very least get even. So not going to happen.
 
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Finally managed to get my hands on a FW900 :)
The AG film was destroyed so I had to remove it entirely. I must say the colors on this thing are beautiful. Geometry is perfect. Had some convergence issues but fixed them entirely with the Dcnv procedure in WINDAS and now it's perfect! Gotta love the fact it has 135 zones to adjust compared to 45 as my two F520 and one Dell P1130 have AND the 4 controls instead of 2 (adjust the green beam separetely). It took me 4 days to complete it with warmups up to 10 hours before calibration to make sure it doesn't drift any further and now it's perfect even in the corners or sides of the image!
Unfortunately the monitor has severe focus problems :(
I spent hours and hours trying to fix this but with no luck. Check out the photos. The focus is good and sharp in the center but as you move to the top or the bottom of the image the horizontal lines become more blurry and foggy. Adjusting the two focus pots on the FBT can solve the problem at the top and bottom of the image but at the expense of the center of the screen which is unacceptable.
Curiously, the focus is very good on the sides of the monitor with no thickening of the lines as you go up or down, considering they are furthest apart from the center of the screen. The issue is present only on the top-middle and bottom-middle parts of the screen. So if you were to look at the first horizontal line at the top of the screen, it is very focused on the hard left and hard right of the screen but becomes extremely blurry as you move toward its middle section.
I even played with some dynamic focus parameters found in WINDAS. For the CR1 chassis (F520, Dell P1130, etc) you have HDF_DELAY_LO and HDF_DELAY_HI. On the FW900 you have two awkward ones: H_SIZE_ORIGIN and H_DF_XB3_HI but they only affect the sides of the screen not the top-middle and bottom-middle parts :(
Any suggestions?
 

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P1x3L

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That's not the problem. They would have to rebuild many production lines to produce various components. It wasn't profitable for them to maintain in the 2000s, it would be even less profitable to build everything from scratch today. A CRT display today would have to cost a fortune to justify the expenses. Not happening.
What evidence is there that companies didn't kill the CRT due to it not having the profit margin that the LCD has... Versus Not making enough profit to keep a company running? The LCD killed the CRT, the CRT did not kill himself ;)
 

Strat_84

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Finally managed to get my hands on a FW900 :)
The AG film was destroyed so I had to remove it entirely. I must say the colors on this thing are beautiful. Geometry is perfect. Had some convergence issues but fixed them entirely with the Dcnv procedure in WINDAS and now it's perfect! Gotta love the fact it has 135 zones to adjust compared to 45 as my two F520 and one Dell P1130 have AND the 4 controls instead of 2 (adjust the green beam separetely). It took me 4 days to complete it with warmups up to 10 hours before calibration to make sure it doesn't drift any further and now it's perfect even in the corners or sides of the image!
Unfortunately the monitor has severe focus problems :(
I spent hours and hours trying to fix this but with no luck. Check out the photos. The focus is good and sharp in the center but as you move to the top or the bottom of the image the horizontal lines become more blurry and foggy. Adjusting the two focus pots on the FBT can solve the problem at the top and bottom of the image but at the expense of the center of the screen which is unacceptable.
Curiously, the focus is very good on the sides of the monitor with no thickening of the lines as you go up or down, considering they are furthest apart from the center of the screen. The issue is present only on the top-middle and bottom-middle parts of the screen. So if you were to look at the first horizontal line at the top of the screen, it is very focused on the hard left and hard right of the screen but becomes extremely blurry as you move toward its middle section.
I even played with some dynamic focus parameters found in WINDAS. For the CR1 chassis (F520, Dell P1130, etc) you have HDF_DELAY_LO and HDF_DELAY_HI. On the FW900 you have two awkward ones: H_SIZE_ORIGIN and H_DF_XB3_HI but they only affect the sides of the screen not the top-middle and bottom-middle parts :(
Any suggestions?
You should never have to touch the potentiometers on the flyback, they are always adjusted perfectly from the start and you can only make this worse. In your case there may be a failure somewhere on the D board impacting the horizontal/vertical dynamic focus circuits. The horizontal lines sharp in the center and blurry on the bottom/top are typical of a dynamic focus issue.
 
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You should never have to touch the potentiometers on the flyback, they are always adjusted perfectly from the start and you can only make this worse. In your case there may be a failure somewhere on the D board impacting the horizontal/vertical dynamic focus circuits. The horizontal lines sharp in the center and blurry on the bottom/top are typical of a dynamic focus issue.
Focus does drift due to moisture and temperature variations. I've seen it on one too many CRTs. More to that, not all of them are perfectly calibrated at the factory. Anyway, that is not an issue, I'm quite skilled at refocusing them, I've done it hundreds of times and I use a magnifing lens ;)
Now, you say is a D-board issue? The thing is the two windas parameters I mentioned earlier do work in making a difference but not the one I need AND I've seen this exact issue on a Samsung 19" 997MB monitor that was pretty used up. Changing the ENTIRE mainboard from a new one did nothing to correct this. Ofcourse I tried refocusing but with no succes. This FW900 is also beat-up and I got it for free so I'm trying to exhaust all possibilities before getting rid of it.
 

Strat_84

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Focus does drift due to moisture and temperature variations. I've seen it on one too many CRTs. More to that, not all of them are perfectly calibrated at the factory. Anyway, that is not an issue, I'm quite skilled at refocusing them, I've done it hundreds of times and I use a magnifing lens ;)
Now, you say is a D-board issue? The thing is the two windas parameters I mentioned earlier do work in making a difference but not the one I need AND I've seen this exact issue on a Samsung 19" 997MB monitor that was pretty used up. Changing the ENTIRE mainboard from a new one did nothing to correct this. Ofcourse I tried refocusing but with no succes. This FW900 is also beat-up and I got it for free so I'm trying to exhaust all possibilities before getting rid of it.
Well, the problem looks very much like something wrong with the dynamic focus. It's hard to be more specific without checking the monitor. ;)
But the failures possibilities I can think of are the following:
- the most obvious, something failed directly in the dynamic focus circuits (D board then). In such case it would be more likely to have a problem on vertical or horizontal focus though, not both.
- something wrong with one or several lines of the power supply (G board) which then affects the circuits controlling focus.
- something wrong with the control circuitry generating the signals for dynamic focus (N board)
- a failure of some components in the vicinity of the flyback or the flyback itself (D board again).

I can't say anything about the Samsung as I don't know that model and I can't find a service manual. I don't know either what kind of circuitry is on the mainboard.
 
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Well, the problem looks very much like something wrong with the dynamic focus. It's hard to be more specific without checking the monitor. ;)
But the failures possibilities I can think of are the following:
- the most obvious, something failed directly in the dynamic focus circuits (D board then). In such case it would be more likely to have a problem on vertical or horizontal focus though, not both.
- something wrong with one or several lines of the power supply (G board) which then affects the circuits controlling focus.
- something wrong with the control circuitry generating the signals for dynamic focus (N board)
- a failure of some components in the vicinity of the flyback or the flyback itself (D board again).

I can't say anything about the Samsung as I don't know that model and I can't find a service manual. I don't know either what kind of circuitry is on the mainboard.
I was trying to point out that the tube itself might be worn out. I'm the third user and the second user got it refurbished as far as I know. Due to aging, the cathodes's surface that emits electrons increases because the central part loses emission material thus the focal point becomes a larger spot. The monitor can't maintain an uniform focus across the screen. In a way the monitor loses "resolution".
Now, if you look at the pictures, the problem affects ONLY the horizontal lines NOT the vertical ones.
The FBT looks ok in my opinion. Both pots glide smoothly without any jumps and I can set the focus perfectly top and bottom but doing so sacrifices the center.
 

Strat_84

Limp Gawd
Joined
Jul 16, 2016
Messages
332
I was trying to point out that the tube itself might be worn out. I'm the third user and the second user got it refurbished as far as I know. Due to aging, the cathodes's surface that emits electrons increases because the central part loses emission material thus the focal point becomes a larger spot. The monitor can't maintain an uniform focus across the screen. In a way the monitor loses "resolution".
Now, if you look at the pictures, the problem affects ONLY the horizontal lines NOT the vertical ones.
The FBT looks ok in my opinion. Both pots glide smoothly without any jumps and I can set the focus perfectly top and bottom but doing so sacrifices the center.
Except if it were a tube issue you'd have the same focus issue on the entire display area. So no.

If I look at the pictures it seems both lines are affected, but these aren't very good pictures. You have the screen in front of you, if you tell me the problem is only with the horizontal lines then you have your answer. The problem is either with the vertical dynamic focus section of the circuit on the D board, the +15V / -15V lines or the N board.

edit: ahaha, mistake. :p
Looking back at the schematics the vertical dynamic focus is a circuit actually separated from the vertical deflection. That kind of signal goes to the flyback.
 
Last edited:

SH1

[H]ard|Gawd
Joined
Jun 30, 2006
Messages
1,410
When I had IBM P275 friend of mine bought some older non-flat Trinitron and it used exactly the same phosphor and coating as GDM-FW900 and thus also had inferior color/contrast.
If CRT era was allowed to continue some more then we would definitely have much better displays to choose from today, including Diamondtron offerings. This is so sad :(
I've found the picture quality of the FW900 to be great. Not quite that of the F520, where the thing I most noticed is the latter display's superior uniformity in luminance across the screen.

Blacks definitely suffered with the antireflective film removed. Still liking the Kantek filter.

Very sad indeed that CRT production ended without a proper successor in terms of raw PQ. OLED first sign of such a successor hopefully.
 
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