TV scart @ power on

[boyofwax]

Hi folks,

I have this very strange problem, maybe someone can explain. I have a Sony Wega TV set on whitch I am only using the SCART input for S video. I have connected a 9V battery to pin 8 and 18 of the SCART connector. This makes the TV switch to the SCART input at power up. When I use an internal voltage like the 11v comming from the PS, or 9v after a 7809 my TV goes on and off without a picture. Could this be due to a switched mode PS? I don't get it, maybe someone can explain?

 

[Steerpike]

Some equipment - (Philips VHS machines being the ones I know) put serial control (RC5) data on Pin8 of the SCART as well, so it's sometimes more than just a hi/lo enable signal.

 

[boyofwax]

Some equipment - (Philips VHS machines being the ones I know) put serial control (RC5) data on Pin8 of the SCART as well, so it's sometimes more than just a hi/lo enable signal.

Any of this should be eliminated by using a diode and capacitor, which I have already tried.