Successes and Challenges With Dreamcast VGA Cables and LCDs

Need help with your PC or Modding Projects?
evildragon
8-bit
Posts: 27
Joined: Wed Aug 02, 2006 3:18 pm

Post by evildragon »

Mozgus wrote:
evildragon wrote:here's a video of it being set... notice when I do start pushing the clock up, the picture shifts a "TINY" bit to the right with it, all I have to do is keep pushing the clock to 100, then the right part of the image will be cut off, but there will be a TINY gap on the left.. I just recenter the image by shifting the picture to the left slightly, and the WHOLE picture is perfectly fit then, with nothing being cut off...

also notice the LCD does now see the signal as 640x480.. It says ever since I lied to the LCD about the image.. essentially, this LCD "learns"...

http://blackevilweredragon.spymac.com/sync.AVI

(it's not divx, it's MotionJPEG, straight from the camera, so any media player can play it, it's just 6 megs)

Yeah, I understand that. Doesn't apply to me though. My H-Position does not shift far enough to the left. I always have a big 1.5 inch black bar. Your "Clock" setting is the same as my "Coarse" setting. It slowly stretches the image so that on low resolution analog signals, you can try to find the size which distributes the pixels best amung the LCD's native display.

Hmm, I don't know if this will work, but I read somewhere that you can put a resistor on the H-Sync line to help shift it. I can't confirm this, but it may be possible.. Just add a POT instead of a resistor, so that way, you can adjust it live...

I hope that does work..

Just out of curiosity, does your LCD monitor have an "auto" mode for it's VGA setting? If so, while sitting at the Dreamcast BIOS screen, keep hitting the Auto until it looks closest. My LCD got VERY close without my help, by just hitting Auto a bunch of times.. Maybe that way it will re-calibrate the H-Position, and allow a little more...
User avatar
Mozgus
Next-Gen
Posts: 6624
Joined: Sat May 13, 2006 10:31 pm
Contact:

Post by Mozgus »

evildragon wrote:Hmm, I don't know if this will work, but I read somewhere that you can put a resistor on the H-Sync line to help shift it. I can't confirm this, but it may be possible.. Just add a POT instead of a resistor, so that way, you can adjust it live...

I hope that does work..

Just out of curiosity, does your LCD monitor have an "auto" mode for it's VGA setting? If so, while sitting at the Dreamcast BIOS screen, keep hitting the Auto until it looks closest. My LCD got VERY close without my help, by just hitting Auto a bunch of times.. Maybe that way it will re-calibrate the H-Position, and allow a little more...

Yeah but what type of pot resistor should I try? What rate of ohms and watts?

Yeah it has an auto mode, but that wont magically allow it to shift further left then possible. When I did the auto mode, it would set the coarse setting perfectly, so that every DC pixel was spread across about 4 LCD pixels and looked great, but I still had the huge left bar, and a huge chunk cut off the right side.
evildragon
8-bit
Posts: 27
Joined: Wed Aug 02, 2006 3:18 pm

Post by evildragon »

Mozgus wrote:
evildragon wrote:Hmm, I don't know if this will work, but I read somewhere that you can put a resistor on the H-Sync line to help shift it. I can't confirm this, but it may be possible.. Just add a POT instead of a resistor, so that way, you can adjust it live...

I hope that does work..

Just out of curiosity, does your LCD monitor have an "auto" mode for it's VGA setting? If so, while sitting at the Dreamcast BIOS screen, keep hitting the Auto until it looks closest. My LCD got VERY close without my help, by just hitting Auto a bunch of times.. Maybe that way it will re-calibrate the H-Position, and allow a little more...

Yeah but what type of pot resistor should I try? What rate of ohms and watts?

Yeah it has an auto mode, but that wont magically allow it to shift further left then possible. When I did the auto mode, it would set the coarse setting perfectly, so that every DC pixel was spread across about 4 LCD pixels and looked great, but I still had the huge left bar, and a huge chunk cut off the right side.

I don't know which rating POT, I will have to see what kind of resistor was used, which I don't even know where I saw this information... (it might have been on this forum, or another)...
User avatar
Mozgus
Next-Gen
Posts: 6624
Joined: Sat May 13, 2006 10:31 pm
Contact:

Post by Mozgus »

evildragon wrote:I don't know which rating POT, I will have to see what kind of resistor was used, which I don't even know where I saw this information... (it might have been on this forum, or another)...

I finally got around to trying this but I have a problem. Which colored wire is for the H-Sync? I have a feeling its either the white or the grey one, but I dont want to proceed until I know for sure. Here's a picture of the the VGA box's circuit board with the 15 pin VGA cord's wires lined up.
Image
evildragon
8-bit
Posts: 27
Joined: Wed Aug 02, 2006 3:18 pm

Post by evildragon »

Mozgus wrote:
evildragon wrote:I don't know which rating POT, I will have to see what kind of resistor was used, which I don't even know where I saw this information... (it might have been on this forum, or another)...

I finally got around to trying this but I have a problem. Which colored wire is for the H-Sync? I have a feeling its either the white or the grey one, but I dont want to proceed until I know for sure. Here's a picture of the the VGA box's circuit board with the 15 pin VGA cord's wires lined up.
Image

i personally would install the POT on the VGA cable going to the monitor itself (past the capacitors).. i've never done it before though.. i can't tell which wires are which in that picture, whoever made it doesn't seem to have labeled the circuit board..
User avatar
Mozgus
Next-Gen
Posts: 6624
Joined: Sat May 13, 2006 10:31 pm
Contact:

Post by Mozgus »

evildragon wrote:
Mozgus wrote:
evildragon wrote:I don't know which rating POT, I will have to see what kind of resistor was used, which I don't even know where I saw this information... (it might have been on this forum, or another)...

I finally got around to trying this but I have a problem. Which colored wire is for the H-Sync? I have a feeling its either the white or the grey one, but I dont want to proceed until I know for sure. Here's a picture of the the VGA box's circuit board with the 15 pin VGA cord's wires lined up.
Image

i personally would install the POT on the VGA cable going to the monitor itself (past the capacitors).. i've never done it before though.. i can't tell which wires are which in that picture, whoever made it doesn't seem to have labeled the circuit board..

Um, I don't have anything to lose here.
Post Reply