MiSTer FPGA Forum

Hi just wondering if there's any harm in leaving the 5v jumper on the IO board for the VGA port, it's required for Antonio's SVIDEO/Composite device but I want to make sure it won't be a problem to leave that jumper in place even when I use the VGA port for Component video (YPbPr).

The VGA connector spec has a dedicated pin for +5V. It would be absurd for anything to have problems from it since it's how a VGA port is supposed to behave in the first place. Anything that doesn't need it will just not wire it, or else they would be literally asking for trouble.

Assuming a passive cable with no extra processing, your component cable should ignore that pin completely since it's not needed on the component end (ie. 3xRCA, so it just needs the red, green, blue, and common ground).

The +5v pin on VGA was added much later. Original VGA cables had the pin removed as a key. There's a (slim) potential to damage older devices that pre-date the +5v pin. Better to not have it when not needed.

legacypixels wrote: ↑Wed Sep 16, 2020 12:35 am

There's a (slim) potential to damage older devices that pre-date the +5v pin. Better to not have it when not needed.

So if you have PVMs from 2005-2007, you should be safe to leave it on? I'd like to be able to switch between composite and component without having to remove the 6-screws required to get into my case every time...

Just to note, I bought a VGA extender cable, and it didn't work at all with my composite adapter, probably because it didn't have the +5V pin hooked up at all... so, I have to wonder if the VGA to BNC cable I got even has it connected, since it's absolutely not needed in that case?

eobet wrote: ↑Sat Jan 28, 2023 2:32 pm

legacypixels wrote: ↑Wed Sep 16, 2020 12:35 am

There's a (slim) potential to damage older devices that pre-date the +5v pin. Better to not have it when not needed.

So if you have PVMs from 2005-2007, you should be safe to leave it on? I'd like to be able to switch between composite and component without having to remove the 6-screws required to get into my case every time...

Just to note, I bought a VGA extender cable, and it didn't work at all with my composite adapter, probably because it didn't have the +5V pin hooked up at all... so, I have to wonder if the VGA to BNC cable I got even has it connected, since it's absolutely not needed in that case?

If you use a cable with the 5v pin missing (old VGA cable) or a VGA to BNC, you should be fine, as there's no path for the 5v.