Composite mod for ZX Spectrum 48k

I have been recently reliving my youth and have bought an old ZX Spectrum, one of my first computers!  The main reason I picked this up was to test my latest game! Yes that's right it's for the ZX Spectrum! Why? Well, why not?  It's actually a port of Lost Little Spaceman and should be ready for release soon.

Before I could test the game on the real spectrum, I was strugging with the RF out, as it needed an analogue tuner.  So I fixed it with a simple mod that isolates the RF Module and wires the composite video signal directly to the socket.  I though this may be of use to others, so here are my steps to complete this:

Firstly, I can't take all the credit as the infomation was from here -

You will need the following items to complete this:

The first step is to open the modultaor box, then de-solder the power and the video signal from the board and bend them up and out the way, as pictured below. Use the solder wick to clean up the old solder on the underside of the board where video signal connection is.


Now fit the capacitor.  Positive needs to be soldered to the board at video connection (see picture) and the negative can be fed though the spare insulated hole on the rf modulator and soldered directly to the centre pin of video socket.  I just reheated the existing solder on the pin to connect and left the existing resister there.  Pictured below.


The best thing about this mod, is that it is very easy to reverse. 

I then powered it up and found that the TV was seeing the signal as SECAM, not PAL as expected.  To fix this I slowly rotated the trimmers and pots.  There is a good article about this here -


After a few lines of basic (still got it!!!) to display all the colours, I ended up with a picture like this. Reminds me of my Sam Coupe boot screen!


I guess the next thing to do is replace all the capacitors and do the DC-DC mod as it's an issue 2 board, but that's for another day. I hope this entry will be of help to others. I expect my next post (quite excited!) will be about my ZX Spectrum release of Lost Little Spaceman.  Bye for now!





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