EMI filters for hsync and vsync.

[fabiodl]

I noticed that the dreamcast vga box (pics here https://shmups.system11.org/viewtopic.php?p=867369#p867369)
use emi filters in series with the hsync and vsync lines of the VGA.
I am replicating the circuit. What EMI filter would you use?

[Terry Bites]

Hi
Your link is to a whole blog- no chance of finding the specific schematic.
Are you referring to the pull-up reistors and diodes on the sync lines?
They are simply there to clamp the DC levels of the sync pulses.

[fabiodl]

The link is to the post which contains pictures of the board.
The H and V lines are, indeed, protected by a diode.
One EMI filter is in series, just before the vga connector, of each of the h and v lines.

[Terry Bites]

I tried you link again. Takes me to a page full of stuff that I'm not going to bother sieving.

[dmills]

I also got a page of rather confused discussion of prehistoric game console video outputs...

The sync outputs are likely driven by some sort of digital logic output which will have a rather fast edge rate in comparison to the output of whatever video DAC the thing uses, I think I would probably throw some filtering on there if I was designing it.

Probably just some sort of small ferrite bead and a 100pF cap, should be fine.

[fabiodl]

There's no DAC in the device itself, it goes straight into the monitor.