Weird RF output for a Spectrum 48+

[flaviosr]

Dear All,
I have been given a Spectrum with a weird RF output as for attached pictures (it also had issues on the membrane but now it's new).
The computer seems working (it's not so easy to handle it.
I am not an expert but I think it's only an issue of the RF modulator and not something more critical: what do you think? If I am right, I was wondering about trying a S-Video mod!
Thank you for your experience

 

[SiriusHardware]

Make a temporary connection between the video-in connection to the modulator and the composite-in connector of any display you have which supports composite video in. (You will also need a connection from GND of the Spectrum, to the outer ring of the RCA type composite - in connector on the display). If the video is OK up to the point where it enters the modulator you should get a reasonable picture. If you do, you know your problem is the modulator but before you draw that conclusion try tuning it in on a different TV.

 

[cj7hawk]

+1 - SiriusHardware's suggestion is good. There are two wires going into the side of the modulator. Many people take the top off the modulator, desolder the resistor going to the output of the RCA connector, solder a wire to the output, run this through the spare hole in the side of the modulator, and solder it to the "middle" wire that carries the composite video signal into the modulator.

Then you can plug a RCA to RCA video lead into the Spectrum and your TV.

David

 

[bola_dor]

You will get better results to the composite video output using a 100uF electrolytic capacitor from the video input to the RF modulator to the central pin output (negative to the output) remember to cut the resistor existing to that pin and cut the 5v wire to the RF modulator.

 

[SiriusHardware]

At the moment I think flaviosr only wants to know if his modulator is good or bad, hence the temporary diagnostic measures suggested so far.