European TV's got a SCART connector with RGB inputs, which is great for use as an arcade monitor for this project. Connecting SCART pin 8 to 12V tells the TV to switch over to 4:3 AV mode. I wired it up, but my Philips TV does not seem to switch to AV when the 12V is already present at the time of powering on. I would turn on the cab and just get snow on screen.
My solution was to use one of the cheap relay time delay boards off Ebay. When I got it I could not get it to trigger the relay, though. Turns out, they added a wrong series diode as reverse polarity protection. The 5V relay engages at 4.5V, but this regular diode had a voltage drop of 0.7V... Good luck trying to make that run on 5V...
Bypassing the diode with a blob of solder did the trick:
And wired into the cab it's switching the AV at startup perfectly: