Sync trouble

[pdiggitydogg]

I recently finished modding my super CD rom2 for rgb, using an amp from a member here. I used a mini din 9 connector, from a model 2 Genesis. Everything works....mostly.
I'm running the Scart leads through a Hama splitter, along with Scart leads from my Sega Saturn and model 1 genesis. From the splitter, into pure sync rgb cable and into a DVDO vp30 scaler.
The Sega units work perfectly, on their own...
The pce only displays a picture when either Sega unit is on...without, there is no picture! I have no cross talk between anything, or so I thought.
What the heck??

I am pulling sync from the sync pin, at the expansion port. Should I try composite video instead? Composite video is currently tapped at the av jack, along with audio - because reasons.

[Keith Courage]

 I've always used composite video out for sync. Try that.

[pdiggitydogg]

Ok, I tried composite video to the sync pin - same issue.
I tried alternative ports on the Hama with no change. Neither Sega unit has affect on the other, when they are on...

Oh. I should also mention that the cable that I am using works with my Sega Nomad without issues.

[pdiggitydogg]

Agh! It was the 5v...
I had a good connection, but for some reason the av jacknis only showing 0.5v. Tapped 5v at the expansion port and its working. I am guessing the Hama has a 5v bar shared across everything, no matter what.

[GohanX]

Btw, unless the amp was specifically built with Sega cables in mind you may not be getting optimum picture.  Sega cables gave resistors and caps on the rgb lines.

[pdiggitydogg]

It's an aftermarket cable from retroconsoleaccessories, not the pal Scart lead

[Ergot_Cholera]

The 5v line to the din 5 socket of the Super CD-ROM² is not connected (at least it wasn't on mine). I had problems with RGB and fast blanking switching until I realised this.

[pdiggitydogg]

That's interesting. I am getting some voltage at mine, but clearly not much.
There is a pad there, connected to a resistor, I believe (?)