Dreamcast VGA box circuit help

[Haros]

So, we've got the classic dreamcast vga box circuit



everything is ok. It's simple to be done.
Just one question about electronic theory.
Why we placed the +5v line on the sync lines? What output do we get from that? From the diodes I guess that what we output has some negative voltage so we try with the diodes to "cut" the negative part.

Anyone keen on electronics to help?

[Niode]

I think you're getting a bit confused. Those aren't diodes. They're resistors.

http://www.owlnet.rice.edu/~elec201/Boo ... _elec.html Read up on this stuff before you go hacking anything more serious.

[Haros]

Hey, I think I was misunderstood.

I was actually talking about the 2 diodes and their use on this circuit.

Now I just want to know why the 5V line gets connected to the sync out.

[Niode]

I see, it wasn't very clear from your post.

The diodes are connected to ground.

All diodes do is make sure current flows in one direction. Sort of like a valve in plumbing.

[Haros]

Hmm I see. How about the +5V line connected to the h-sync and v-sync?

It seems like we try to output digital logic voltage (0 - 5v) or something...