Most of the so-called “Home computers” we have in our collection were meant to be used with the old bulky CRT television sets. Back in the day you would use a coax cable to connect your computer to the TV via the RF input. Some models like the Commodore 64 have a dedicated RGB video output and you would solve the problem by making a simple composite video cable. The lucky ones who had SCART back in the day would have enjoyed the full RGB experience. Some like the ZX spectrum have only a RF output and this is inconvenient to use in our modern TV sets with digital tuners. In this article we will show you how you can modify your ZX spectrum to output composite video from the RCA output.
Things you will need:
- 100uf/25V electrolytic capacitor
- Soldering iron with solder
- Desoldering station or pump
- Philips screwdrivers
The first thing after you open your ZX spectrum is to disconnect the keyboard and remove the board from the case.
Second thing is to locate the TV tuner (metal box on the upper left corner of the board) and pop off the top cover. Next, desolder and gently move away the resistor attached to the center pin of the RCA jack, so that it won’t make accidental contact with the jack.
Next desolder from the board the two leads on the left side of the tuner and bend them upwards to the metal case.
After desoldering the leads, you end up with two solder points on the board. The point that is closest to the corner of the board is the composite video output, you need to solder the positive lead of the capacitor there. Then route the negative lead of the capacitor through one of the holes on the plastic insulator and solder it to the center pin of the RCA jack. The capacitor is used to filter the composite signal so that you get a cleaner image.
After putting everything back together you will have composite video coming out the RCA jack.