negative sync / dreamcast VGA

As per my previous post, I now have a second hand BG1208. This is a lovely machine, but only supports negative sync on input 5.

What's my best option if I'd like to link up my dreamcast via a VGA box? (subject to being careful of burn in of course)

a) use a dreamcast vga box with existing cable - it will work, or the box can be fettled to fix it.

b) dreamcast vga box, plus custom cable to input 3 (would really rather not do that, as it will mean an extra memory block, extra cabling etc). Although if I connect up the dreamcast using the existing cable at 640x480x60Hz it'll mean an extra memory block anyway...

c) male->female db15 with circuitry to fix negative sync

d) output svideo on vga box and input through wintv card (I'd rather not do that, as I was hoping to see if the lightgun worked on the screen, for a bit of fun)

e) give up and leave the dreamcast connected to the TV.

any ideas?

PK

 

Hi there,

I am in the same predicament with my 800...

I found a site that shows how to feed negative sync from a positive sync signal, I dont really get why barco felt the need for neg instead of positive, it doesnt make much sense,

anyway. There is a small 7404 motorola chip that can be used to convert the signals. I just got one of these for 20p from here: http://www.crownhill.co.uk/item273.htm

All you need to do then is:

http://www.twobit.com/sync.html

and maybe make a nice little box with bnc connectors on

When I get the chip i will check this out with my blade dreamcast vga box and report back.

Cheers,
Jon

 

Hi guys could you tell me were i could pick up a dreamcast VGA box and how much they are? I'd didn't even know you could get this connection for a dreamcast.
Thanks
Samir

 

When these projectors were designed positive sync wasn't around much. It was only when other PC manufacters wanted to get out of paying IBM royalty for using the VGA standard that the spec shanced. The output drive from video cards was (and in many cases still are) not a high enough voltage to produce sufficient signal. In the majority of cases an interface box was used to feed the projector the propper signal and still provide the local monitor with a feed.

You should be able to pick up one of these for about £10 secondhand.