RGB from VGA

Kyosho · Post by **Kyosho** » Tue Nov 28, 2006 3:11 am

This isn't like other topics where some one is trying to get the PSOne LCD to input VGA, or get a 360 to output VGA. What I have is a small media playing device that has outputs for both composite and VGA. I want to hook it up to the PSOne LCD. I have no interest in doing a real VGA mod. That's not useful to me as much. What I want to figure out is where to find the analog RGB signals that are there before they're converted to VGA (before they're 15khz or whatever..blah, I don't know this stuff).

How would I go about finding them? Just, like, a basic idea of what to look for. Note that I don't currently have a multimeter, though I'll be getting one very shortly. Nor a digital camera to take a picture of the board.

I mean, if they're not there, I could always do the VGA mod, or use composite. But I'm thinking they're there, and it'd save me some work (VGA) or quality (composite). As I said, I don't think I can find them without some pointers. I'm assuming some of you here know how the VGA signal is created, and would know where I could find them. Anything?

Post by **gannon** » Tue Nov 28, 2006 3:35 am

Are you sure the rgb lines are even originally 15khz? I'd think they'd be 30, then scaled down for composite (in non-discrete circuitry like an IC).
Anyways, a list of chip names in the devices could help in finding the area where the rgb points might be.

Post by **marshallh** » Tue Nov 28, 2006 3:09 pm

edit: disregard my reply, I just realized that the rgb lines aren't going ro be synced at 15khz like I was assuming...

You're in luck!

Here's what VGA is:
- Regular old RGB with seperate 31KHz sync signals

Here's what composite video is:
- Luma, chroma, 15KHz composite sync signal

Here's what the PSone LCD needs:
- Regular old RGB with 15KHz composite sync signal.

See what you do? Connect the RGB lines off the VGA output of your thingy to the inputs on the psone lcd. Then, run the composite video signal through a LM1881 sync seperator chip and the LCD is happy.
Don't have an LM1881? The PSone lcd has one on-board.
Just connect your composite video output fo the thingy to Pin #2 on the LM1881 chip on the back of the LCD. It's a very small 8-pin SMT chip, so be careful.

Disclaimer: I haven't tried this myself but I have every reason to believe it should work.

sammy · Post by **sammy** » Wed Nov 29, 2006 5:57 am

you could use an rgb encoder...

Post by **gannon** » Wed Nov 29, 2006 4:49 pm

which would give you no better signal than the composite signal you put into it.