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Main => Monitor/Video Forum => Topic started by: swirlee on April 12, 2019, 07:16:06 pm

Title: Trouble getting my NVidia GPUs to export vga signal to Makvision CRT
Post by: swirlee on April 12, 2019, 07:16:06 pm
Hello,

I am revisiting a MAME build I never fully realized. Initially I was connecting an old laptop that had VGA out to a Makvision M2929D4G-TS CRT monitor. This worked without issues running at 800x600 resolution at 60Hz. However I am now trying to replace this laptop in my build with an old gaming desktop for performance reasons. I'm encountering issues getting the desktop to send a usable signal to the CRT. The desktop has two EVGA GTX 570 HD connected via SLI and the machine is running windows 7 with latest video drivers and updates. These video cards do not have VGA out but I purchased this cable  (https://www.amazon.com/dp/B00B2HP8AW/ref=cm_sw_em_r_mt_dp_U_WLrSCbR28MNA7) which I assumed could step down the DVI signal to VGA. Windows detects the CRT as a Generic Monitor and says the native revolution is 1024x768, which I believe is incorrect. However, no matter what resolution, or refresh rate I select, I cant seem to send a signal to the Makvision CRT that it accepts. I have tried enabling/disabling SLI, having the CRT plugged into one gpu and my test lcd monitor(so I can see whats going on) into a different card or having just the CRT connected to the PC after a restart hoping windows would output the correct resolution.

Any ideas what I could be doing wrong or what the bottleneck in hardware/software is? 

Thank you     
Title: Re: Trouble getting my NVidia GPUs to export vga signal to Makvision CRT
Post by: Arroyo on April 13, 2019, 08:02:06 am
Someone can correct me if I’m wrong but I believe modern GPU’s aren’t software wise setup to output the lower resolutions your seeking.  That is why efforts have been made to hack the drivers to allow at it.  This has been done with ATI/AMD cards by Calamity, but not for NVIDIA (although I believe soft15khz will work for Nvidia just not as easy to setup/manage).

Most people are now using ATI/AMD cards with VGA/DVI-I output and using Calamity’s driver in combination with GroovyMame to achieve native resolutions of the original games.  Maybe even more importantly native refresh rates.  In looking up your monitor it looks like it may be 30khz, so you may need to generate some scan lines to make 15khz (most games) look like they did originally.

I’d head over to the GroovyMame forum and start doing a lot of reading, once you get it setup it’s incredible.
Title: Re: Trouble getting my NVidia GPUs to export vga signal to Makvision CRT
Post by: Lorien on April 13, 2019, 10:55:43 am
I second Arroyo's answer. I did that with a CRT TV and it's like I'm Running a 15Hz Only Arcade monitor. If you get yourself and AMD Radeon 5450 you'll pay it 50$ or less. And it's the Model Calamity uses while developing CRT_Emudriver according to his instruction so you're less likely to have bug with that model. Groovymame is also a fork of MAME made by Calamity to complement the CRT_Emudriver and has switchrez builtin so it auto change your resolution when you launch the rom no need for external software to do that. Very smooth experience.
Title: Re: Trouble getting my NVidia GPUs to export vga signal to Makvision CRT
Post by: swirlee on April 14, 2019, 02:55:59 am
Thanks for your replies. I have some updates.

To clarify a few things this is a “high resolution” CRT capable of displaying 1024x768 but runs best at 800x600 at 60Hz which is how I’ve been using it.

So the laptop I was using had a dedicated VGA port. The video cards in the desktop I am switching to only has HDMI and DVI. Of course I know under a lot of circumstances DVI can step down to VGA with just an adapter or cable but I thought maybe in this instance this isn’t the case. So today I bought a GTX 750 ti of craigslist, which my research told me was Nvidia fastest GPU that still had a dedicated VGA port. Sure enough this worked! However I’m having a new problem now. Because widows doesn’t automatically display the exact resolution and refresh rate this monitor needs I have to connect a second display via HDMI. When I tell the GPU to send 800x600 at 60Hz to the CRT it pops on and looks good. But as soon as I disconnect the hdmi monitor the CRT switches off because I guess windows tries to default to the CRT but at the resolution the other monitor was set at. Not sure what to do here. Any ideas?
Title: Re: Trouble getting my NVidia GPUs to export vga signal to Makvision CRT
Post by: Lorien on April 14, 2019, 11:01:56 am
You need a modified Driver to get the proper Resolution and refresh rate, that's why we pointed you to CRT_Emudriver. The catch is it work only with AMD Radeon 5000+. I recommand the 5450.

http://geedorah.com/eiusdemmodi/forum/viewtopic.php?id=295

Read it out, it's well documented and It will do both low res and Hi res.
Title: Re: Trouble getting my NVidia GPUs to export vga signal to Makvision CRT
Post by: MiteWiseacre on April 16, 2019, 09:23:40 am
I have this same card
In dual monitor settings make the VGA your main screen. Then disconnect the HDMI, then reboot with only the VGA connected. Should work
Another thing, if you can get this card to actually display 240p, let me know please. You can make it a custom resolution but I think it steps up to 480 no matter what.