Adding RGB *input* to a screen that has only composite

[alexbird]

I know this is the opposite of what many of you will have been doing to screens.

I have this screen left over from a previous (aborted) project, it is like this one currently on ebay.co.uk:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0350660475

I want to incorporate it into my new toy - an xbox based media centre - so I can use it to play music without powering up the tv.

Problem: This screen has composite in, I use RGB (scart) on the tv for higher quality. The xbox appears to reset when you switch between the composite and RGB cables. I would prefer to be able to switch between modes without a reset!

The LCD use the OM8362, which is the same as the TDA8361 (datasheet).

Looking at the datasheet and some tv schematics (bottom of this page), it looks like you can just pull pin 21 high and feed RGB through pins 22-24.

When I do this I just get a black screen though.

Largely pointless photos of board and mods:
http://www.subtlelogic.co.uk/projects/x ... gp4906.jpg
http://www.subtlelogic.co.uk/projects/x ... gp4908.jpg
http://www.subtlelogic.co.uk/projects/x ... gp4913.jpg
http://www.subtlelogic.co.uk/projects/x ... gp4914.jpg

Has anyone done the conversion this way around, or got any suggestions?

[Kurt_]

Didn't look at the pictures. I think I know your problem though.

A few questions:

1) Are your grounds hooked up?

2) You're not pulling a CSYNC signal from the chip, are you? This is required for RGB.

[alexbird]

Didn't look at the pictures. I think I know your problem though.

A few questions:

1) Are your grounds hooked up?

Yes, at least well enough to see some results.

2) You're not pulling a CSYNC signal from the chip, are you? This is required for RGB.

I'm not pulling anything from the chip, the chip is already part of the LCD, I'm connecting different inputs.

I connected pin 20 from the scart, which is used for composite sync in RGB mode, to the composite input of the chip. This is how it appears in the tv schematics.

[Kurt_]

The only thing I can think of is something is a tad sensitive, and the composite (which has video and sync on it) needs to be separated before you can use it as csync. Just a guess though, I haven't a clue.

[XCVG]

The only thing I can think of is something is a tad sensitive, and the composite (which has video and sync on it) needs to be separated before you can use it as csync. Just a guess though, I haven't a clue.

Seconded. Try building a sync separator or test it with something with seperate sync.

[hansmaas]

Hello,

Can you tell me from which product you took those 4 pcb pictures ????

thanks
Hans