My SRD510 arrived, and the first step was to modify it to permanently display video and audio received at the Decoder SCART.
In the olden days of analogue satellite TV, a lot of channels were encrypted. Most PAL programmes intended for UK audiences (e.g. all the Sky channels) were encrypted using Videocrypt. Given that the SRD510 was intended for the Sky-viewing UK public, it has an in-built Videocrypt decoder. Snazzy.
But...some people wanted to watch more exotic transmissions, encrypted using different standards and often not intended for UK viewers. To satisfy them, Amstrad included a Decoder SCART socket round the back of the SRD510. The idea was that the scrambled video received by the receiver would be fed out to the external decoder, the decoder would work its magic, and then would send the unscrambled video/audio back to the SRD510 - all via the Decoder SCART. To 'tell' the Amstrad to play the decoded video/audio, the external decoder would output 12 volts to pin 8 of the Decoder SCART socket.
So...merely connecting the PC's video output to the Decoder SCART wasn't enough. I tried it, turned the PC on, checked my HDMI-to-RCA converter...but the screen remained blank. I needed to find a way to 'pipe' 12 volts to pin 8 of the Decoder SCART socket. Luckily, the (archived) SatCure website came to the rescue, suggesting that I solder a wire from pin 8 of the receiver's TV SCART socket (which is always at 12 volts - presumably to tell the TV that the receiver is powered on) to pin 8 on the Decoder socket. I did this, and hurrah! The screen flickered into life, and I was staring at my PC desktop via a 30-year-old satellite receiver in slightly fuzzy 576i.
Next step - to get the PC to respond to the Amstrad's remote...