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What would cause the VGA output to fail?

Posted: Fri Jun 25, 2021 7:52 pm
by SolidSonicTH
I bought a Dreamcast to mod for a friend's birthday present but when I hooked it up to my VGA box I wouldn't get any output (plus the little red light on the box wouldn't come on). It outputs Composite okay so the video port is working but is there something that would prevent the VGA out from functioning properly? Could it just be my specific VGA box (there was one mode on my OSSC that would get an image for a split second then lose sync so maybe it is working, just not with this hardware)? It works on my personally modded Dreamcast but I'm not sure why it's not working on this one.

If push comes to shove I might even just swap out the motherboards between this and one of my other DCs that I don't use over VGA.

Re: What would cause the VGA output to fail?

Posted: Fri Jun 25, 2021 9:00 pm
by Bob Dobbs
Preliminary questions:
What region console?
What game was it?
Is it an official GD-ROM game disc or other?
If other, please describe?

One note I dealt with twice in the NTSC/U world.
Not all modern TV's work with the direct VGA connection. On two TVs, I had to use a VGA to 5-BNC adapter and 5-BNC to VGA adapter for the VGA to work. Fortunately, we have a bunch of those at work. I am not saying this is your issue, but I thought I would throw it out there.

Re: What would cause the VGA output to fail?

Posted: Fri Jun 25, 2021 9:22 pm
by SolidSonicTH
NTSC-U, same as the one I already know works. Tried it through an OSSC, on a flat-panel monitor, and then a CRT VGA monitor and none of them picked it up.

I was just at the Dreamcast BIOS screen.

GDEMU, although I had this problem before I installed the mod as well.

Re: What would cause the VGA output to fail?

Posted: Fri Jun 25, 2021 10:43 pm
by Ian Micheal
Depends on the game some dont work

Re: What would cause the VGA output to fail?

Posted: Sat Jun 26, 2021 11:15 am
by Bob Dobbs
Ian Micheal wrote:Depends on the game some dont work
What game was it? To note, not all games support VGA. Did you try various games?

Re: What would cause the VGA output to fail?

Posted: Sat Jun 26, 2021 12:36 pm
by SolidSonicTH
I said I didn't get to try any games, it doesn't get VGA output from boot. I can't even view the BIOS menu with the VGA box plugged in.

Re: What would cause the VGA output to fail?

Posted: Sat Jun 26, 2021 5:20 pm
by Bob Dobbs
Be cool as none of us are getting paid for this! To note, you actually did not say that verbatim, but I get it. Now, the only solution I have is the same one I listed earlier which is what I did to make mine work (see attached pictures). I hope it is not your OSSC, and I do wish you luck getting this resolved.

Here is a quote from RetroRGB.com:
"The Open Source Scan Converter is a zero lag upscaler. At the moment, it is by far the sharpest way to play your analog consoles via HDMI, offering tons of options, 2x 480p (960p) and up to 5x 240p (1080p!). It’s only shortcoming is it’s not compatible with all TV’s in every mode, but it’s still an excellent choice and what I recommend to all retro-gaming videophiles!"

https://www.retrorgb.com/ossc.html

Below are the adapters that saved me on two of my 5 TVs with a Dreamcast attached to it. I hope this helps.
VGA to 5-BNC.jpg

Re: What would cause the VGA output to fail?

Posted: Sat Jun 26, 2021 6:41 pm
by pcwzrd13
If the red light on the VGA box isn't turning on then there's a fuse blown on the motherboard. I forget the exact component but basically the box isn't getting the 5v it's supposed to get.

Re: What would cause the VGA output to fail?

Posted: Sun Jun 27, 2021 2:27 am
by Bob Dobbs
pcwzrd13 wrote:If the red light on the VGA box isn't turning on then there's a fuse blown on the motherboard. I forget the exact component but basically the box isn't getting the 5v it's supposed to get.
That too. I did not have that issue.

Re: What would cause the VGA output to fail?

Posted: Sun Jun 27, 2021 5:50 pm
by SolidSonicTH
pcwzrd13 wrote:If the red light on the VGA box isn't turning on then there's a fuse blown on the motherboard. I forget the exact component but basically the box isn't getting the 5v it's supposed to get.
I think this is the answer I was trying to target. Also apologies if I sounded testy, I just thought people were saying things that were already said.

Anyway, if that's the case, can that fuse be replaced?