Sony BVM-20f1u Troubleshooting Help Please!

[Duke Wellington]

Hello. I'm relatively new to these forums, but I want to have a retro gaming setup, so I bought a retro studio CRT with RGB input via BNC leads, but I wanted to connect the monitor to my PC for emulator use. After much research and many months of trial and error of making failed home-brewed VGA to BNC-4 converters, and temporary give-ups on the project, I finally caved in and bought the appropriate gear to do all the conversion and adaptation from RGBHV from a VGA source to RGBS on a BNC-4 source. I am now in the process of fiddling with settings in nVidia control panel to output to the right analog signal, which should be easy since the monitor supports NTSC and PAL, and even their variants like 240p. I also made sure to output with the correct sync polarity based on the BVM's manual, and I estimated the largest resolution I could possibly get away with on this monitor (based on the dot pitch and inch size of the tube screen) on this thing as being either 1280x960i@15Hz in 4:3 aspect or 1280x720i@~15Hz in 16:9 aspect ratio, though nVidia Control Panel tends to be finicky about what it allows as the maximum resolution--probably the decoder on the monitor doesn't have support for non-TV input signals.

Anyways, long story short, this is what ends up being displayed on the monitor in 230x240p@60Hz mode (after fixing scaling issues in the nVidia Control Panel--note that trying to display in 640x480i@30Hz mode tends to crash my display drivers for some reason):

(Excuse the Windows 10 being used for retro emulation)

The problem seems to be in incorrect sync information being provided by the signal, but I've invested a hefty sum of research and money into making sure that it gets the correct sync information, even if nVidia hardware doesn't natively output composite sync information like AMD probably still does.


Also, here are the cable setups:

The BNC-5 cable being used as a BNC-4 cable with RGB and Composite Sync being input into the default decoder for the monitor:


The BNC-5 cable being connected via four cables into a VGA->BNC-4 adapter:


A pricey Sync Combiner I purchased to convert between RGBHV to RGBS from VGA to VGA, connected to the VGA->BNC adapter:



Finally, here's some screenshots of my nVidia Control Panel configuration (as you can see I can take screenshots of the 240p second monitor, so thought I would include that in the screenshot):

As you can see, the BVM is undetected via EDID information, but it shows up as a generic analog display device, used as a secondary (or technically tertiary) monitor:


And very important to show are the custom resolution settings provided to the BVM here. The manual requires that the sync polarity be negative, which appears like it already is in automatic mode, other than that I'm unsure of how to set the front pixel porch, sync width and such; maybe my issue lies here:

[niall]

If you can't figure it out, an Extron Emotia Plus is currently for sale here: http://shmups.system11.org/viewtopic.php?f=4&t=53187

Usually it's easier to have the main desktop at 31kHz and just run 15kHz to the BVM as a secondary display, get it to auto-start at boot on that screen etc. Check out GroovyMAME and Calamity's AMD 4xxx drivers as to what's possible, if Nvidia hardware can do what you need here.

[Duke Wellington]

Yes, thank you for posting that, but I was hoping to avoid the extravagant cost of getting a full-fledged A/V switch with fancy filters and all that. Having failed making one myself, it was expensive enough just buying the sync combiner--which I would've just bought an AMD video card for my system that already has composite sync output and the end result would've been cheaper except for the fact that I have a laptop--and the sync combiner's not something on that user's trading list.

[Fudoh]

Are you sure that your graphics card is able to output 15khz ?

The multiple images you get on that windows screen suggest that you're feeding more than 15khz.

Also I'm pretty sure that that 15Hz resolution isn't going to work. The BVMs requires standard TV timings. 240p60 or 480i60.

[Duke Wellington]

Yeah I suppose that's my problem then, is that the video card is feeding a 31 kHz horizontal sync signal instead of a 15 kHz TV-format one. Do you have any extra advice for me being able to do what I want to do (hooking up the BVM to my PC using nVidia hardware--or else some cheap alternative)?

Also, where'd you learn the stuff you know?

P.S. When Sony advertises 900 TV lines, do they do so fully knowing that no signal can utilize such resolution on the perfectly capable tube, if not just for the inept decoder (which I assume is the bottleneck in disallowing higher resolutions, albeit lower frame rate)?

[kamiboy]

TV lines does not mean what you think it does.

[Duke Wellington]

Well according to the .3 mm aperature grille pitch, and the 20" screen, there should be enough individual addressable phosphors to actually have 900+ vertical scan lines (actually a little above 960 if I calculated right), if the electronics were there to allow it (the magnets and electron gun should do it though). But in any case I'll just take it as the tube being capable, but the rest of the TV not. Also, according to nVidia Control Panel, it does report being able to output 15kHz resolutions, like here:




And finally, yes, I remembered I know the 900 TV lines figure was meant to describe horizontal resolution in terms of widescreen non-square pixels, but the aperature grille pitch and size of the tube (by my calculation) allow just over 1280 horizontal phosphor slots in the grille, and it was by coincidence that it also should allow just over 960 vertical pixels if the aperature grille pitch also measures height--and which is why I forgot that TV lines weren't meant to describe the vertical lines--but all this is only the case if the manufacturer implements the grille structure throughout the entirety of the tube, which to me it does look like so.


Edit:
Actually I now realize that the aperature grille .3 mm pitch only describes the horizontal pixel width, and the height of the pixel is probably as big as a scan line (which I just calculated as .8 mm), so I guess I took that .3 mm figure a little too far.





Anyways, technical babble aside, I'd still appreciate help.
Here's a nice reference to aid in helping me with timing formula: http://wiki.osdev.org/Video_Signals_And_Timing

[crabfists]

Hi,

I have been down this road before. Like fudoh said you are going to need to get your graphics card to output 15Kzh as it sounds like it is currently outputting 31Khz. You can do this with software or hardware. The software route would involve using something like Soft15Khz or CrtEmuDriver.

Soft15Khz does not run so well (if at all) on modern versions of Windows and will involve you using old versions of nvidia or ati drivers. I ended up installing Windows XP on a seperate box for this reason.

CrtEmuDriver apparently runs better on newer windows versions but I think it will only work with ATI cards. You need to use a modified version of the ATI drivers. I know of someone who has got CrtEmuDriver working on Windows 7 with their PVM as a second screen, so this is possible.

The hardware route is to get something like an ArcadeVGA card, but I think they are not cheap.

[BazookaBen]

All I needed to get 15hz on a AMD HD7970 was CRU to create the resolution, and Quickres to select it. Of course, it would be nice to have a secondary monitor to use, because Windows won't boot in 15hz.

[Duke Wellington]

CrtEmuDriver apparently runs better on newer windows versions but I think it will only work with ATI cards. You need to use a modified version of the ATI drivers. I know of someone who has got CrtEmuDriver working on Windows 7 with their PVM as a second screen, so this is possible.

The hardware route is to get something like an ArcadeVGA card, but I think they are not cheap.

Thank you. I will try the Arcade VGA Card for sure.

If that doesn't work, I might try CrtEmuDriver unless I can paravirtualize the monitor to virtual machine with an old operating system on it with custom drivers (but either way I'm pretty sure that the host system's video drivers and hardware are merely abstracted to the guest OS, and thus have to deal with its setbacks).



Edit:
Will this work? Since I have a laptop, it seems ideal in usability, even if it is not so ideal to emulate rendering at a higher resolution than intended and downscaling with this back to original resolution.


The only potential issue I notice is that it doesn't list 240p as a possible output, and the only 480i mode it outputs does so at 60Hz, yet it still claims being able to do so with 15 kHz output.

• CGA (15K) (480i @60Hz)